India; Rain Water Harvesting, Conservation and Management Strategies for Urban and Rural Sectors

1. IntroductionWater is essential for all life and used in many

different ways, It is also a part of the largerecosystem in which the reproduction of the biodiversity depends. Fresh water scarcity is not limitedto the arid climate regions only, but in areas withgood supply the access of safe water is becomingcritical problem. Lack of water is caused by lowwater storage capacity, low infiltration, larger interannual and annual fluctuations of precipitation (dueto monsoonic rains) and high evaporation demand.

The term water harvesting was probably usedfirst by Geddes of the University of Sydney. Hedefined as the collection and storage of any form ofwater either runoff or creek flow for irrigation use.Meyer’s of USDA, USA has defined it as thepractice of collecting water from an area treated toincrease runoff from rainfall. Recently Currier ,USAhas defined it as the process of collecting naturalprecipitation from prepared watershed for beneficialuse. Now a days water harvesting has become ageneral term for collecting and storing runoff wateror creek flow ,resulting from rain in soil profile andreservoirs both over surface /under surface.Previously this was used for arid and semi arid areas,but recently their use has been extended to sub humidand humid regions too. In India water harvestingmeans utilizing the erratic monsoon rain for raisinggood crops in dry tracks and conserve the excessrunoff water for drinking and for rechargingpurposes.

2. History of Rain Water HarvestingWater harvesting like many techniques in use

today is not new. It is practiced as early as 4500B.C. by the people of Ur and also latest by the

Nabateans and other people of the Middle east.While the early water harvesting techniques usednatural materials, 20th century technology has madeit possible to use artificial means for increasing runofffrom precipitation.

Evenari and his colleagues of Israel havedescribed water harvesting system in the Negvedesert. The system involved clearing hill sides tosmooth the soil and increase runoff and then buildingcontour ditches to collect the water and carry it tolow lying fields where the water was used to irrigatecrops. By the time of the Roman Empire, these runofffarms had evolved into relatively sophisticatedsystems.

The next significant development was theconstruction of roaded catchments as described bythe public works Department of Western Australiain 1956. They are so called because the soil is gradedinto ditches. These ditches convey the collectedwater to a storage reservoir. Lauritzan, USA hasdone pioneering work in evaluating plastic andartificial rubber membranes for the construction ofcatchments and reservoirs during 1950’s. In1959,Mayer of water conservation laboratory, USAbegan to investigate materials that caused soil tobecome hydrophobic or water repellent. Thengradually expanded to include sprayable asphaltcompounds, plastic and metal films bounded to thesoil compaction and dispersion and asphalt fiber glassmembranes. Early 1960, research programmes inwater harvesting were also initiated in Israel by Hillaland at the University of Arizana by Gluff. Hillal’swork related primarily to soil smoothing and runofffarming. Cluff has done a considerable amount ofwork on the use of soil sealing with sodium salt andon ground covered with plastic membranes.

National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur

1. Rain Water Harvesting, Conservation and Management Strategiesfor Urban and Rural Sectors

* Dr. R. K. Sivanappan

* International Consultant in Water Resources & Irrigation,No:14, Bharathi park, 4th Cross Road, Coimbatore 641 043

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STATE OF THE ART LECTURE

Water harvesting was practiced more than1000 years back in South India, by way ofconstruction of irrigation tank, ooranis, temple tanks,farm ponds etc, but the research in India on thissubject is of recent one. Work is taken up atICRISAT, Hyderabad, Central arid Zone ResearchInstitute, Jodhpur, Central Research Institute fordryland Agriculture (CRIDA), Hyderabad, StateAgricultural Universities and other dry land researchcenters throughout India.

In Pakistan, in the mountainous and dryprovince of Balukhistan, bunds are constructedacross the slopes to force the runoff to infiltrate. InChina, with its vast population is actively promotingrain and stream water harvesting. One very old butstill common flood diversion technique is called‘Warping’ (harvesting water as well as sediment).

When water harvesting technique are usedfor runoff farming, the storage reservoir will be soilitself, but when the water is to be used for livestock,supplementary irrigation or human consumption, astorage facility of some kind will have to beproduced. In countries where land is abundant, waterharvesting involves; harvesting or reaping the entirerainwater, store it and utilize it for various purposes.In India, it is not possible to use the land area only toharvest water and hence water harvesting meansuse the rain water at the place where it falls to themaximum and the excess water is collected andagain reused in the same area. Therefore themeaning of water harvesting is different in differentarea/ countries. The methods explained above areused for both agriculture and to increase the groundwater availability.

The water harvesting for household and forrecharging purposes are also in existence for longyears in the world. During rainy days, the people inthe villages used to collect the roof water in thevessels and use the same for household purposesincluding drinking. In South East Asian countriespeople used to collect the roof water ( thatched roofby providing gutters) by placing 4 big earthern drumsin 4 corners of their houses. They use this water forall household purposes and if it is exhausted onlythey will go for well water. The main building of theAgricultural College at Coimbatore was constructed100 years ago and they have collected all the roofwater by pipes and stored in a big under groundmasonry storage tanks by the sides of the building.

These rainwater are used for all labs, which requirepure and good quality of water. In the same waythe rainwater falling on the terrace in all the buildingconstructed subsequently are collected and storedin the underground masonry tanks Even the surfacewater flowing in the Nalla’s in the campus are alsodiverted by providing obstructions, to the open wellsto recharge ground water.

Hence Rainwater harvesting is as old ascivilization and practiced continuously in differentways for different purposes in the world The onlything is that it has not been done systematically in allplaces. Need has come to harvest the rainwaterincluding roof water to solve the water problemseverywhere not only in the arid but also in the humidregion.

3. Need for Rain Water HarvestingWater is a becoming a scarce commodity and

it is considered as a liquid gold in this part of thecountry (especially in Coimbatore, Erode, SalemDistricts of Tamil Nadu). The demand of water isalso increasing day by day not only for Agriculture,but also for household and Industrial purposes. It isestimated that water need for drinking and othermunicipal uses will be increased from 3.3 MHm to7.00 MHm in 2020/25. Similarly the demand of waterfor industries will be increased by 4 fold i.e. from3.0 MHm ti 12.00 MHm during this period At thesame time more area should be brought underirrigation to feed the escalating population of thecountry, which also needs more water. But we arenot going to get one litre more water than we get atpresent though the demand is alarming.

The perennial rivers are becoming dry andground water table is depleting in most of the areas.In Coimbatore, the depletion is about 30-50m in thelast 30-40 years. Country is facing floods and droughtin the same year in many states. This is because, noconcrete action was taken to conserve, harvest andmanage the rain water efficiently.

The rainfall is abundant in the world and alsoin India. But it is not evenly distributed in all places.India being the monsoonic country, the rain falls onlyfor 3 to 4 months in a year with high intensity, whichresults more runoff and soil erosion. Total rain occursonly in about 100 hours out of 8760 hours in a year.It also erratic and fails once in 3 or 4 years. This isvery common in many parts of the country.

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The availability of water in the world, in Indiaand in Tamil Nadu is given below with rainfall.

Places Rainfall Population Availability ofin mm Water/Person/Yr

M3/P/YearWorld 840 6 Billion 700India 1150 1.0 Billion 2200Tamil Nadu 925 62.5 Million 750

If the availability of water is 1700 M3/p/y,there will be occasional water stress, and if it is lessthan 1000 M3/p/y, it is under water scarcity condition.Though India is not under water stress conditionsbut Tamil Nadu state is already under water scarcitycondition, but there is no need for panic since it ispossible to manage this condition as in the case ofIsrael where the availability is only about 450 M3/p/y, by means of water harvesting, water conservationand water management.

Water scarcity / stress is not limited to thearid regions; only but also occurring in high rainfallareas also. Chirapunji gets more than 11,000mm ofaverage annual rainfall but face drinking waterproblem before monsoon commences whereas inRalegoan Siddhi, in Maharastra there is no waterscarcity problem though the annual average rainfallis only about 450mm. Hence to mitigate waterproblem / drought etc, there is an urgent need tofollow our ancestral way of water harvesting andthe latest technologies adopted in Soil and waterconservation measures on watershed basis includingroof water harvesting etc which are described indetail below.

The Theme paper on Water vision 2050 ofIndia, prepared by Indian Water ResourcesSociety(IWRS) has indicated that a storage of 60MHm is necessary to meet tbne demand of waterfor irrigation, drinking and other purposes. But thepresent live storage of all reservoirs put together isequivalent of about 17.5 MHm which is less than10% of the annual flow in the rivers in the country.The projects under contruction (7.5 MHm) and thosecontemplated (13 MHm) are added, it comes only37.50 MHm and hence we have to go a long way inwater harvesting to build up storage structures inorder to store about 60 MHm.

More than 75% of the areas comes under

hard rock in Tamil Nadu. Further the porosity of therock is only about 3%. The natural recharge ofrainwater in this region is only about 8 -12%, whichis very minimal. Therefore there is an urgent needto take up the artificial recharge of the rain for whichwater harvesting and water conservation structuresare to be build up in large scale. The rainfall in coastalarea is more than 1200 mm (Chennai) still; drinkingwater is a problem in almost every year. This isbecause the entire rainwater is collected in masonrydrains (from houses, streets/roads etc) are taken tothe sea instead of taking into the ground wateraquifers or in surface reservoirs by pumping if needbe. The ground water available can be used duringsummer and make the aquifer empty so that therainwater can be put into the aquifers during rainyperiod by suitable water harvesting measures.

All the above details indicate the need forwater harvesting measures in urban and rural areafor the use of Agriculture, drinking and otherpurposes.

4. Methods of Water Harvesting in Rural andUrban Areas

There are different / various system of waterharvesting depending upon the source of watersupply and places as classified below.a) In situ Rainwater harvesting

• Bunding and terracing.• Vegetative / stone contour barriers.• Contour trenching.• Contour stone walls.• Contour farming.• Micro catchments.• Tie ridging methods• Farm ponds.

b) Direct surface runoff harvesting• Roof water collection• Dug out ponds / storage tanks• Tankas• Kundis• Ooranis• Temple tanks• Diversion bunds• Water spreading

c) Stream flow / runoff harvesting• Nalla bunding

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• Gully control structures• Check dams – Temporary

Permanent• Silt detension tanks• Percolation ponds

d) Sub surface flow harvesting• Sub surface dams• Diaphragm dams

e) Micro catchment’s / watershed• Inter terrace / inter plot water harvesting• Conservation bench terrace

f) Runoff inducement by surface treatment• Roaded catchments• Use of cover materials – Aluminum foils,

Plastic sheet, bentonite, Rubber, etc• Using chemicals for water proofing, water

repellent etc. to get more run off water.

A comprehensive watershed development onwatershed basisincluding water harvesting structuresare given in the figure 1.

5. Plan of Action for Rainwater HarvestingAs stated early, rainwater harvesting is as old

as civilization and is practiced in many countriesincluding India from time immemorable. Butgovernment and people remember this only whenwater is not available even for drinking purposes.There is no use of spending huge sum of moneywhen we notice the water scarcity for drinking,industry and agriculture. These activities / structureshould be taken / constructed before the rainy seasonso that the rain water which goes as runoff outsidethe sub watershed / city limits can be collected andused directly or by recharging into the ground.Government is undertaking the wasteland /watershed development programs, but not done in acomprehensive / integrated manner / holisticsaturating the watershed in all water harvestingmeasures. Hence there is a need to take upwatershed development programmes – mainly waterharvesting measures in a scientific and systematicmanner.

The government of Tamil Nadu has laidcondition that in any building construction, waterharvesting work should be included and executed,but in practice, it is not perfect. The authoritiesconcerned should monitor the programme so thatthe drinking water problem can be solved in all

municipalities / corporation without any difficulty tosome extent.

To sum up the following types of WaterHarvesting System for different uses can beimplemented in different parts of the country.

No. Region Types of Water Use

1 Arid Artificial catchments Drinking plains to capture rainfall

(tankas or kundis inRajasthan)

Tanks or talabs in DrinkingRajasthan to capture andsurface runoff irrigation

Embankments / Irrigationobstructions across water & alsodrainage / Nalla to for rechargingcapture surface runoff

2 Semi Tanks / Ponds/Eri to Irrigation Arid capture surface runoff water and places and also chains of drinking water

tanks called cascade. throughrecharge ofground water

3. Flood Mud embankment Irrigation plains which may be water and

breached during the drinking waterfloods. through

rechargingground water

4 Hill and Diverted stream flows Irrigation Mountain Jammu, M.P., water region Maharastra

6. Case Study In Water HarvestingThere are numerous case studies available in

water harvesting both in Rural and Urban sectors.In Rural areas it is Soil and Water conservationmeasures taken on watershed basis to conserve andaugment ground water. In the urban sector, it ismostly roof water harvesting for direct use andrecharging the ground water and also collecting ofsurface runoff from pavements / roads andrecharging it into the ground through recharge pitsor using abandoned / existing wells. The followingare the places where rain water / roof water

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harvesting has been implemented in a successfulmanner.1. Rural areasa. Ralegoan Siddhi in Maharastra stateb. Lakshman Nagar and Varisai Nadu inTheni Dt., Tamil Nadu.c. Alankulam Taluk in Tirunelveli Dt., Tamil Nadu.d. Aravari watershed in Alwar Dt., of Rajasthan.e. Maheshwaram watershed in Andhra Pradesh.f. Kapilnalla watershed in Karnataka

2. Urban SectorsMostly the roof water harvesting measures are takenup.a. Indiai. Tamil Nadu Agricultural University, Coimbatore, all main buildings.ii. PRICOL, Periyanaickenpalayam (Industry Building), Coimbatoreiii. TWAD Board / office and PWD office at Chennai.iv. Numerous Apartment buildings in Chennai.v. Sundaram and Clayton Ltd, Padi, Chennai – (Industry buildings)vi. TVS training schoool at Vanagaran, Chennaivii. Rastrapathi Bhavan, Delhi.viii. Center of science and environment building at Delhi.ix. Institute of economic growth, New Delhi.

b. Foreign Countriesi. Thailand – Many houses including thatched houses in villages.ii. Japan – office complex.iii. Germany – office buildings.iv. Singapore – office buildings.

Rules and regulations have been framed forRain Water Harvesting in all corporation,municipalities and panchayat unions in Tamil Nadu.The Gujarat government has issued a generalresolution for the effort that no new constructionwould be allowed if it does not have provision forroof top rainwater harvesting. This would be validin all 143 municipalities and 6 urban developmentauthorities in the state. It is heartening to note thatConfederation of Indian Industries (CII) andFederation of Indian Chambers of Commerce andIndustries (FICCI) have taken action to implement

the rain water harvesting to their Industry premises.If the above measures are implemented in

Rural and Urban areas, the drought in rural areasand drinking water problem in Urban and Ruralpopulation can be solved to some extent. The people,NGO, and Government should joint together andimplement the rain water harvesting in a big way inall places in the years to come to solve water scarcityproblem in the country.

7. ConclusionsIt is very important to make water everybody’s

business. It means a role for everybody with respectto water. Every household and community has tobecome involved in the provision of water and inthe protection of water resources. Make water thesubject of a people’s movement. It means theempowerment of our Urban and Rural community,i.e., to manage their own affairs with the state playinga critical supportive role.

Further involving people will give the peoplegreater ownership over the water project includingwatershed development, Soil and Waterconservation and water harvesting will go a longway towards reducing misuse of government funds.It will also develop the ownership (own water supplysystems), they will also take good care of them. Inthis way it is possible to solve water problems facingthe county in the 21st century.

References• Ake Nilsson, Ground water dams for small-scale watersupply, IT publication, 1988.• Center for science and environment. A water-harvestingmanual, Delhi 2001.• Center for Science and Environment – Making watereverybody’s business, New Delhi, 2001.• Chitale M.A., A blue revolution, Bhavans BookUniversity, Pune 2000.• CII, Rainwter harvesting – A guide, New Delhi 2000.• Rajiv Gandhi, National Drinking water missionsHandbook on Rainwater harvesting, Government of India,New Delhi, 1998.• Sivanappan, R.K., Soil and Water Conservation andWater harvesting, Tamil Nadu Afforestation project,Chennai, 1999.• Sivanappan, R.K. Water harvesting, ICCI, Coimbatore2001.• Stockholm water Symposium – ‘Water harvesting’Stockholm, Aug 1998.• Verma HN & Tiwan KN current status and Prospects ofRain Water Harvesting, NIH, Roorkee, 1995.

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1.0 WHAT NEED TO BE DONE? – Somesuggestions

1.1 Ground Water Recharge, Reuse, andEfficient Systems• Watersheds, Check dams, Roof water

harvesting (should be made compulsory andmandatory), India uses around 15% of rainwater while Israel almost 100% (seeAppendix).

• Efficient irrigation systems: Sprinkler, drip,trickle (macro and micro irrigation). Dripirrigation cuts water use by between 30% and70% , increases crop yield by between 20%and 90%, compared with traditional irrigation.

• Sequential water use : Reuse, recovery andrecycling of waste waters.

• Switching to less water-dependent crops.

2. Water Issues and Related Concerns

* Prof. (Mrs.) Vijaya Agarwal ** Prof. (Dr.) J. H. Agarwal

* Selection Grade Assistant Professor (Electrical Engineering), Department of Agricultural Structures andEnvironmental Engineering, College of Agricultural Engineering, Jawaharlal Nehru Agricultural University,Krishi Nagar, Adhartal P.O., Jabalpur 482 004, Email : [email protected] Phone : 0761 – 2681820

** Retired Director Instrumentation & Project Coordinator UNDP-GOI-MAEP, JNAU, G-83 Krishi Nagar,Adhartal P.O., Jabalpur 482 004 Email : [email protected] Phone : 0761 – 2680400

ABSTRACTBy 2025, world population will be 8 billion – water will become scarcer. Global

farming accounts for 70% of water use, while only 17% of farmland is irrigated andit provides only 40% (estimated) of world’s food. Water application losses in irrigationare quite high – almost 40 % of the total irrigation water is lost. Per capita irrigatedagricultural land is declining – main reason shortage of water. Water table is fallingsteadily in intensive farming regions. People and ecosystems are under threat frompersistent chemicals like pesticides, fertilizers and heavy metals in waters. There areno serious efforts to gain water by practices like rainwater harvesting, watershedsand mini-ponds, reuse and recycling of waste water. It is said there is enough freshwaterin world – however, it is not always available in the right place or right form. Theproblem is mainly of access, distribution, and optimum utilization.

The paper discusses related concerns and outlines what need to be done.Key words : Fresh water, harvesting and conservation of water, water reuse, watermanagement in agro-ecosystems, electronics and IT based devices.

• Water conservation and higher efficiencies forwater-conveyance, water-application andwater-use. Scientific management of water bymaking use of electronics and IT based aidslike soil-moisture measurements.

• Participation of women in conservation ofwater.

• Competent, knowledgeable and experiencedpersonnel to be involved in management ofwater related activities and balanceddistribution of water.

1.2 Water needs of plantsAgriculture accounts for 70% of fresh water

use. It requires as much as 2000 litres of water togrow 1 kg of rice. Water (with elements H + O) isa vital component for crop growth. Plants needwater for:

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• Temperature regulation,• Photosynthesis,• Transport of nutrients from soil to plant, and• Transport of assimilates from plant parts to the

produce location.

1.3 Excess water harmfulExcess water to crop is harmful. It causes/

results in :• Spoilage of soil-health, salinity built up.• Loss of nutrients due to excessive leaching.• Contamination of surface and ground water.• No proportionate increase in yield, and wastage

of water and energy.

2.0 SOIL-MOISTURE MEASUREMENTSYSTEMS

A variety of electronics and microprocessor-based devices for soil-moisture measurement areavailable for scientific water management in agro-ecosystems. Some of the devices are based onelectrical impedance, infrared thermometry andtime-domain reflectometry. Salient features of fivesuch devices are given below:1. Gro-Point GP-ERS Moisture Sensor and

Irrigation Management System (ESIEnvironment Sensors Inc., Canada,web site : www.esica.com ).

• Soil moisture range: 5 – 50 % (volumetric) +/-1%.

• Rechargeable battery or mains operated.• Available with hand-held display or with data

logger.• Intelligent Irrigation System, with a set of

sensors, computer, software and irrigation controller.

2. Moisture-Point, Multi-Probe Sensor MP-917(ESI Environment Sensors Inc., Canada,web site: www.esica.com ).

• Soil moisture range : 0 – 50 % (volumetric) +/-1.5%.

• A single probe gives moisture profile.• Rechargeable battery or mains operated.• LCD display or datalogger or RS-232 with

PC.

3. Irrometer-Tensiometer Probe (IrrometerCompany, USA,

web site: www.irrometer.com).• Tensiometric principle, indicates the amount of

moisture available to plants.• Direct display of moisture.• Automatic control of irrigation systems.

4. Watermark Soil Moisture Sensor – 200SS(Irrometer Company, USA,web site : www.irrometer.com ).

• Solid state, electrical resistance type.• Available with meter, electronic control unit.• Low cost.

5. Sentek Soil Moisture Probes – EnviroSCAN,EnviroSMART, EasyAG and Diviner 2000(Sentek, Australia,web site : www.sentek.com.au ).

• Electrical capacitance principle, continuousmeasurement of soil moisture over multipledepths in root-zone.

• Easy installation, data download options forretrieving data in the field or remotely.

• Provides information on crop water use andwater management in root-zone, facilitatesdecisions on how much and when to irrigate.

These devices should be used for scientificmanagement of water in agro-ecosystems to makeefficient use of water and to minimize problems likewater logging, salinity built up, non-pointcontamination (see Appendix , Fig. 2 (a), (b), (c)and (d) for photographs of some soil-moisturedevices).

3.0 IT ENABLED SUPPORT SYSTEMSFOR OPTIMUM UTILIZATION

Use of Crop Simulation Models, Weatherdata and Knowledge Base(s):• To select appropriate crop and crop variety

suitable to agro-climatic pattern, and switch toless water-dependent crops.

• To decide about the date of sowing, duration ofcrop.

• To decide about the irrigation inputs to crop bymonitoring soil-moisture and crop-water stress,to decide when and how much to irrigate, andto optimize utilization of water by usingefficient systems like sprinkler, drip and trickleirrigation.

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• To apply fertilizer to crops through irrigationwater by computer-controlled fertigationtechniques.

• To adopt controlled environment farmingwherever easily feasible: This providesmonitoring and control of lighting, humidity,temperature, CO2 level, irrigation, nutrientssupply, chemical treatments, etc.

• To adopt a GIS coupled soil-water-balancecomputation system to calculate the availableresidual soil-moisture for its better utilization.

4.0 CONCLUDING REMARKSWater is a very valuable resource. There are

no serious efforts to gain water by practices likerainwater harvesting, watersheds and mini-ponds.Rainwater harvesting should be made mandatory.Sequential water use (reuse, recovery and recyclingof waste waters) should be planned whereverpossible so that the load on fresh water can bereduced. Water’s presence in agro-ecosystemsshould be treated on a holistic approach, and byemploying scientific management tools it should bejudiciously used. For agriculture, an integratedwater management practice consisting of three maincomponents – rain water harvesting, water-savingmicro-irrigation, and highly efficient cropproduction – should be adopted. Conservation ofwater should be taken as a way of life and widelyadopted.

SELECTED READING• Goodchild, M.F., B.O. Parks and L.T. Steyaert

(Eds.). Environmental Modelling with GIS.Oxford University Press, New York, 1993.

• Berkhoff, J. A Strategy for Managing Water inthe Middle East and North Africa. World Bank,Washington, DC, 1994.

• Bian, F., Z. Sha and W. Hong. An integratedGIS and knowledge-based decision supportsystem in assisting farm-level agronomicdecision-making. J. Geogr. Syst., 1995, 3, pp.49-67.

• Soil-Moisture Systems. ESI – Canada <www.esica.com > , Irrometer – USA

< www.irrometer.com > , Sentek – Australia <www.sentek.com.au > .

• Hinrichsen, D., B. Robey and U. D.Upadhyay. Solutions for a Water-Short World.

Population Reports, Series M, No. 14.Population Information Program, Johns HopkinsSchool of Public Health, Baltimore, December1997.

• United States Department of Agriculture. ARSNational Program # 201 on Water Quality andManagement : Component I – Agriculturalwatershed management, Component II –Irrigation and drainage management,Component III – Water quality protection andmanagement, 1998 – ongoing. <www.nps.ars.usda.gov >

• Li, F., S. Cook, G. T. Geballe and W. R.Burch. Rainwater Harvesting Agriculture: Anintegrated system for water management onrainfed land in China’s semiarid areas, AMBIO– Journal of Human Environment, Vol. 29, Issue8, December 2000, pp. 477-483.

• Gleick, P. H. The World’s Water 2000 - 2001:The Biennial Report on Freshwater Resources.Island Press, Washington, DC, 2000.

• Rijsberman, F. and D. Molden. Balancing wateruses: water for food and water for nature(Thematic background paper), InternationalConference on Freshwater, Bonn, Germany, 3-7 December 2001.

• Smajstrla, A.G., B.J. Boman, D.Z. Haman, F.T.Izuno, D.J. Pitts and F.S. Zazueta. Basicirrigation scheduling in Florida < http://edis.ifas.ufl.edu/AE111 > Bulletin # 249,Agricultural and Biological EngineeringDepartment, Cooperative Extension Service,Institute of Food and Agricultural Sciences,University of Florida, Gainesville, 2002.

• Fahimi, F.R., L. Creel and R.M. De Souza.Finding The Balance: Population and WaterScarcity in the Middle East and North Africa.Population Reference Bureau, Washington, DC,2002.

• Simonne, E. and G. Hochmuth. Irrigationscheduling as a means of applying the rightwater amount and monitoring soil moisture forvegetable crops grown in Florida in the BMPera. Document # HS909, Horticultural SciencesDepartment, Cooperative Extension Service,Institute of Food and Agricultural Sciences,University of Florida, Gainesville, 2003 < http://edis.ifas.ufl.edu/HS166 >

• Rijsberman, F. Sanitation and Water, In: Global

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crises, global solutions (Ed. - B. Lomborg),Cambridge University Press, Cambridge, 2004,670 p.

• IWMI. Beyond more crop per drop (Noteprepared by F. Rijsberman and D. Molden forthe 4th World Water Forum, Mexico, 16-22March 2006), International Water ManagementInstitute, Sri Lanka, Press release, 17 March2006.

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(c) Sentek Soil-Moisture Probe working oncapacitance principle.

2. Soil-Moisture Probes :

(a) Soil-Moisture Probe for moisture measurements in theroot zone of a crop (Sensors are mounted on a screwableinsert )

(b) Tensiometer type soil-moisture probe.

(d) Soil-Moisture Probe working on impedanceprinciple.

[Note : Photographs of the probes from websites / productliterature. Disclaimer: No preference to any particular firmby the authors].

A P P E N D I X

1. Rainfall Facts : Percentage of Rainfallconsumed to support direct and indirect humanuses of water (Source: IWMI, Sri Lanka)

System / Uses % of RainfallFood – irrigation 2Food – rainfed 4Domestic & industry 1In-stream ecology 8Flood runoff 27Permanent grazing 18Grasslands 11Forests & woodlands 17Arid lands 5All others 7Total 100

INTRODUCTIONIndia is one of the developing countries. Due

to faster industrialization and urbanization andincrease in population water demand is increasingday by day. Rainfall in India is highly irregular. Mostof it is concentrated during a few months of the yearand maximum amount flows away resulting in poorrecharge of ground water. There is significant spatialimbalance in water resource available and waterdemand. Therefore, it is becoming necessary tobring water from distant places increasing the costof conveyance. It is also a common observation thatunderground water table is depleting due touncontrolled extraction of water. The state ofMaharashtra covers an area of 307,713 square kmand supports a population of 82 million. Over halfof this population is in rural area which facesproblems related to water. Conventional sources likeopen well, bore well and piped water supplies havefailed due to depleting water tables, poor waterquality and high cost involved in operation andmaintenance. Every year a great amount of wateris being lost that falls on terraces, all of which findsits way to the storm water drains. Rain water

harvesting can play important role for solving thewater problems.

WHY RAINWATER HARVESTING?Rainwater harvesting means the activity of

direct collection of rain water which can berecharged in to the ground water to prevent fall ofground water level or storing in surface orunderground water tank. It is most suited in today’scontext due to following reasons.1. It is the most scientific and cost effective way

of recharging the ground water and reviving thewater table.

2. It offers advantage in water quality for bothirrigation and domestic use.

3. It provides naturally soft water and containsalmost no dissolved minerals or salts, arsenicand other heavy metals.

4. It can be done at individual as well as in acommunity level. This way we can be selfsufficient in terms of domestic waterrequirements and not just dependent on theactions initiated by government or any otherlocal body.

3. Rainwater Harvesting Techniques

* Dr. K. A. Patil ** G. K. Patil

* Lecturers in Civil Engineering Dept; Govt. College of Engineering, Aurangabad (M.S.) 431 005

ABSTRACTWater is our most precious natural resource and something that most of us take for

granted. We are now increasingly becoming aware of the importance of water to our survivaland its limited supply. The human beings require water for various purposes. The most partof the earth surface i.e. about 71 % is covered by water. Out of total volume of wateravailable on the surface of the earth 97 % is saline water, 2 % water is in the form of iceand glaciers and only 1 % is fresh and potable water. India is well endowed nations in theworld in terms of average annual rainfall. It is unbelievable but it is true that Cherapunjiwhich gets 11000 mm annual rainfall still suffers from serious drinking water shortage.Though India’s average annual rainfall is 1170 mm; in the deserts of western India it is aslow as about 100 mm. Hence, it is necessary to opt for rainwater harvesting measures forfulfillment of water requirement.


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Collecting rainwater as it falls from the skyseems immensely sensible in areas struggling tocope with potable water needs. Rainwater is one ofthe purest sources of water available as it containsvery low impurities. Rain water harvesting systemscan be adopted where conventional water supplysystems have failed to meet people’s needs.

COMPONENTS OF RAINWATERHARVESTING STRUCTUREAll rainwater harvesting structures will have threebasic components:1. Catchment area i.e. the surface area utilized for

capturing the rainwater.2. Collection device, like tanks or cisterns or

percolation pits used for collecting or holdingthe water.

3. Conveyance system i.e. the system of pipes orpercolation pits through which water istransported from the catchment area to thecollection device.

METHODS OF RAINWATER HARVESTINGThere are different ways by which rain water

harvesting is carried out. Some of the importantmethods are discussed one by one as discussed incoming paragraphs.

1. Utilizing Rainwater for Dewas Roof WaterFilter

Dewas is the name of the city located inMadhya Pradesh. This roof water filter is firstpracticed at Dewas and hence the name Dewas roofwater filter. Fig.1 shows details of Dewar roof waterfilter. It can be made easily using sand pebbles ofdifferent sizes. In this two caps are provided as T1and T2. Keep the cap T1 and T2 always closed. TheT2 is used for periodical back washing of filter andcap T1 is used for backwash drainage. Small pebblesof size 6 mm are on entry side of rainwater. Use ofmedicine for water purification is made through capT2. Do not recharge rainwater for first two days inrainy season. Keep the roof always clean, especiallyin rainy season so that quality of rain water fallingon roof is not deteriorated. The cost of this rooffilter excluding connecting pipe is about Rs 800.For average condition in Maharashtra, from 100square metres roof area about 50 m3 of water canbe percolated through this filter.

2. Utilization of Rainwater for Recharging PitWhere there is no well or bore well in the

house, total rainwater falling on the open plot canbe recharged by making recharge pit. Water flowingout of the plot can be directed to this pit. This pitmay get filled 10 to 15 times in one monsoon andcan recharge water up to 200 m3. This method iseffective in the area where permeability of soil ismore. The capacity of the pit may be taken up to 10m3. The percolation of water through this pit of theorder of 200 m3 per annum is possible. The cost ofthis structure may come about Rs 7000.

3. Utilization of Rainwater for Well Recharging Rainwater flowing in the farm is diverted to

a water collecting tank of size 6 m x 6 m x 1.5 mnear well and a small filter pit of size 1.5 m x 1.5 mx 0.6m is made at the bottom of large pit. Otherwisesuitable pit may be excavated depending upon theavailability of space near well. Fig.2 shows detailsregarding recharge of open well by runoff from farm.Filter pit is filled with sand, pebbles larger than 20mm and pebbles/boulders larger than 75mm pebblesis filled in three equal layers and connected to thewell by 150 mm diameter PVC pipe and this pipeprojects 0.5 to 1.0 m inside the well. The capacityof the water tank may be taken about 50 m3. Thepercolation of water 400 to 1000 m3 per year ispossible through this structure.

4. Utilizing of Rainwater for Bore wellRecharging

Arrangement of bore well recharging is asshown in fig. 3. A six metre diameter collecting pitof 1.5 m depth is excavated around the bore wellcasing pipe. Another small pit of 1.5 m x 1.5 m x0.6 m depth is made at the bottom of large pit andfilled with filter media. A 75 mm diameter PVC pipeis connected to the bore well casing pipe after firstlayer of 75 mm pebbles. An inverted elbow isconnected to the pipe.

5. Utilizing Roof Water to Recharge TrenchThe roof water collected can be recharged

through recharge trench. Water can be rechargedthroughout the year either by using used water orrainwater. This recharge trench may get filled manytimes as per availability of used or rain water. Thismethod is effective in the area where permeability

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of soil is more. The capacity of the trench may betaken up to 20 m3. The percolation of water throughthis pit of the order of 100 to 200 m3 per annum ispossible. The cost of this structure may come aboutRs 5000.

6. Utilizing Surface Rainwater to Recharge Tubewell

Depleted aquifers are directly fed with surfacerainwater by using a recharge tube well so thatrecharge is fast and evaporation and transit lossesare zero.

A typical recharge tube well is designed asfollows :1. A borehole of 50 cm diameter is drilled to the

desired depth.2. A 20 cm diameter casing i.e. outer pipe of the

bore well is designed by providing slottedperforated sections against aquifers.

3. The depth of the recharge tube well should beabout 30 metre below the water table in the area.

4. The annular space between the borehole andthe pipe is filled with good gravel and developedwith a compressor till it gives clear water. Tostop the suspended solids from entering therecharge tube well, a filter mechanism isprovided at the top.

5. A pit of dimensions 6 m x 6 m x 6 m is dug withthe tube well at the center.

6. This pit is filled with small rounded boulders,stone chips and sand in layers with boulders atthe bottom and sand at the top.

7. The top one metre of the casing assembly inthis pit is filled with sand. The top of the casingpipe is provided with a cap which is about 600mm below the sand bed to prevent suspendedmaterial from entering the well.

8. In order to release the air present in the casingassembly during the percolation process offloodwater, the air vent is provided through a75 mm diameter pipe connected to therecharging tube well within the top 600 mmthrough a reducer tee of dimensions 200 mm x75 mm. The air releasing pipe is then extendedto one of the banks where the vent isconstructed.

When flood water filters through the sand,most of the suspended materials are filtered out. The

second sand filter surrounding the slotted section ofthe well at the top prevents the remaining suspendedmaterial entering the well. Beyond this is a coirwrapping as a final protective filter before waterenters the well. The rate gradually decreases due tosetting of slit at the top. Every year, after the rainyseason about one meter of the sand at the filter bedhas to be replaced. Every year the well is developedwith a compressor once immediately after thestorage structures become empty because the waterlevel is shallow immediately after the monsoon anddevelopment is effective.

During pumping when the water is clear, itmay be allowed on the filtered bed so that it takesdown the slit accumulated in the filter bed into thewell which is being developed. Through this methodthe entire filter bed also gets cleared of the silt duringthe time of infiltration.

7. Utilizing Roof Water to Collect into the StorageTanks

Rainwater from the roof surface is drainedthrough gutters into storage tanks. To preventcontamination and dust to flow into the storage tanksthere is a provision of a hand movable gutterconnection which can be manually moved to divertthe water out. The rooftop is used as the collectiondevice. Guttering generally made of PVC is used totransport the rainwater from the roof top to thestorage tanks. Storage tanks may be either above orbelow the ground and should be properly covered.In apartments more than one storage tanks can beused and they can be interconnected throughconnecting pipes. The storage tanks should haveprovision of an adequate enclosure to minimizecontamination from human, animal or otherenvironmental contaminants. The end of the gutter,which connects the storage tank, should be attachedwith a filter to prevent any contaminants to get intothe storage tank. It is also advisable to drain thefirst flow to get rid of the dust and contaminantsfrom the roof top.

CASE STUDY OF RAIN WATERHARVESTING FOR BUILDING IN URBANAND VILLAGE AREA

Rain water harvesting system for annexurebuilding of Govt. College of Engineering,Aurangabad is being considered for study purpose.

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The Government Engineering College is located inMarathwada region of Maharashtra State. Theaverage annual rainfall of Aurangabad town isaround 700 mm/year. The population of the city ismore than 10 lakh. Presently the water is suppliedto the town by Municipal Corporation, Aurangabad.Considering the capacity of water treatment plant,the water is supplied to town on alternate day.

The institute needs water about 350 m3 perday. In last few years it is observed that the groundwater level of the town is being depleted. It isessential to conserve the rainwater not only in thecity itself but also in areas surrounding toAurangabad. No one can neglect the importance ofrainwater harvesting. According it is proposed tocollect roof water from at least ten hoses from eachvillage. It is also proposed to collect rainwater fromroof of Annex building of this institute. If this rooftop rain water harvesting scheme is implementedall civil engineering students from this institute willhave a role model. These students will see the systemand in future they will be motivated to implementroof water harvesting system elsewhere. Thetentative estimate is as given below.

Estimate for rain water harvesting system forannex buildingArea of building : 2159.78 m2

Perimeter of building : 335.45 mAverage annual rainfall at Aurangabad : 700 mmCoefficient of runoff : 0.8Quantity of water to be harvested per year :

1209.47 m3

Requirement of soak pit : 6 m x 6 m x 1.5 m (Twonumbers)

I ) Cost of excavation : 2 x 54 m3 x Rs.60/-= Rs. 6480/-

II) Cost of material for filling of soak pita. 75 mm to 100 mm size aggregate

= Rs. 12000/-b. 15 mm to 25 mm size aggregate

= Rs. 12000/-c. Sand = Rs. 8000/-d. Protection wall with perforation

= Rs 8000/-e. Labour cost for filling material ( Lump sum)

= Rs. 6000/-

III) Plumbing costa. PVC pipe 6" size total length 200 m @ Rs

100/- per m = Rs.20000/-b. PVC pipe 4" size total length 120 m @Rs 85/-

per m = Rs 10200/-c. Labour charges (Lump sum)

= Rs 20000/-d. PVC pipe accessories = Rs 10000/-

IV) Tube Well 100 m deep and 2 H.P. pump= Rs.30000/-

Total Expenditure = Rs142680 /-The total cost of rain water harvesting systemproject is Rs.142680/-

Rain water harvesting system for villagecommunity

This system is designed for the villagecommunity situated in locality where there isscarcity of water. The annual rainfall is 650 mm peryear. The water is supplied by panchayat/localauthority alternate day. Incase of summer seasonthe water is supplied by tankers. So it is proposedto conserve the rain water by allowing it to percolateso as to meet underground water. It is proposed toconserve rain water collected on top of every houseand common rain water harvesting system isdesigned for group of 10 houses having approximatearea of 70 m2 each

Estimate for rain water harvesting system forvillage communityArea of group of houses : 700 m2

Perimeter: 340 mAverage annual rainfall: 650 mmCoefficient of runoff: 0.8Quantity of water to be harvested per year: 364 m3

Requirement of soak pit: 3 m x 3 m x 2 m

I) Cost of excavation : 18 m3 x Rs.60/-= Rs. 1080/-

II) Cost of material for filling of soak pita. 75 mm to 100 mm size aggregate

= Rs. 2500/-b. 15 mm to 25 mm size aggregate

= Rs. 2500/-c. Sand = Rs. 2000/-

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d. Protection wall with perforations= Rs 2000/-

e. Labour cost for filling material= Rs. 5000/-

III) Plumbing costa. PVC pipe 4" size total length 200 m @Rs 85/-

per m = Rs.17000/-b. Labour charges (Lump sum)

= Rs 8000/-c. PVC pipe accessories = Rs 6000/-

Expenditure for one unit of ten houses= Rs 46080/-

CONCLUSIONWater is essential element of life. Everyone

knows that, if we do not harness available sourcesof water and use them judiciously with proper carethe problem of water scarcity is going to be serious.Irrespective of fast development in all fields ofscience there can be no substitute to water. Hence,it is necessary to opt for various water harvestingmeasures. It is the responsibility of governmentorganization as well as individual to harvest eachdrop of water falling on earth surface. For this, it isnecessary that each person collect the raindrops

failing on his roof, plot, and farm and recharges itunder ground. Two cases of roof top waterharvesting for urban and rural area have beenconsidered in the present study. Similarly for otherbuilding roof top rain water harvesting can beimplemented. In fact there is no village andhabitation in India that cannot meet its basic drinkingand cooking needs through rainwater harvestingtechniques.

REFERENCES1. Gawai A.A. and Aswar D.S. (2006) “Towards

Self reliance for Water Needs through RainWater Harvesting” Conference on ‘EngineeringTechnology for Efficient Rain Water Harvestingand Soil Conservation’, S.G.G.Nanded, 29-30May 2006.pp. 1-7

2. Kaushal Kishore (2004) “Rain WaterHarvesting”, Journal of Civil Engineering andConstruction Review, May 2004, pp.42-48Magar R.B. and Waghmare S.T. . (2006) “RainWater Harvesting” Conference on ‘EngineeringTechnology for Efficient Rain Water Harvestingand Soil Conservation’, S.G.G.Nanded, 29-30May 2006.pp. 44-51

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IntroductionFor centuries world has relied upon rainwater

harvesting to supply water. Rainwater harvestingpromotes self sufficiency and fosters an appreciationfor water as a resource. It saves money, saves otherresources of water, reduces erosion and storm waterrunoff and increases water quality.

Rainwater can provide clean, safe and reliablewater for drinking so long as the collection systemis properly constructed and maintained and treatedappropriately for its intended use.

Rainwater harvesting means capturing rainwhere it falls or capturing the runoff in a village ortown and taking all precautions to keep it unpolluted.

One third of world’s population willexperience severe water scarcity by the end of thiscentury. In rural areas, the water may not be fit fordrinking due to the polluted water bodies, due tocontaminated ground water and also due to acutewater scarcity. In urban areas, water demand

increases due to increase in the population. Hence,the most effective way to obtain fresh drinking wateris to harvest rainwater. Rainwater harvesting systemis inherently simple in form, and can often beassembled with readily available materials byowners, builders with a basic understanding of theplumbing and construction skills.

The present investigations was proposed witha vision to overcome the scarcity of drinking waterduring the non – rainy seasons such that it giveseasy and economical solution that can be adoptedboth in urban and rural areas.

Sample Collection and StorageRainwater samples were collected from five

different places of Bangalore during October 2005.The samples were stored in good grade plastic cans.

The above samples were tested for physical,chemical and microbiological parameters. Table 1gives the experimental finding.

4. Harvested Rainwater for Drinking

*Dr. N. Balasubramanya

* Professor, Dept. of Civil Engineering, M.S.Ramaiah Institute of Technology, Bangalore – 54

AbstractIt is clear from the World water quantity that out of total available water, only 0.3%

is available for human consumption. But today even this is getting polluted due to humanactivities like mining, industrialization has created acute shortage of potable drinking water.Rain water harvesting is one of the most ancient and easy methods that can be adopted aturban and rural level efficiently.

The aim of this study is to investigate the possibility of using harvested rainwater asa source of drinking water without causing any health risk. This can be achieved by adoptingsuitable storage technique efficient and economical treatment methods.

Roof harvested rainwater samples were collected from five different places ofBangalore during October 2005. The water samples were collected and stored in goodgrade plastic containers and were subjected to periodical treatments (like chlorination,solar disinfections and use of silver nitrate) and tests fro and use of silver nitrate and testsfor physical chemical and Biological parameters up to May 2006 as per IS 10500:1991.

All the above treatment methods suggested proved to be highly effective in reducingthe colonies fro an initial value of around 300 to zero.


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A detailed study of Table 1 reveals that boththe physical& chemical parameters are very muchwithin the limits for drinking water standardsspecified by WHO (1984) and IS 10500:1991.However, the colony counts were quite significantin all the five samples.

Therefore, it was decided to emphasize moreon the microbiological contaminations and suitabletreatment methods to make the rainwater fit fordrinking.

Treatment methods and ResultsAll the five rain water samples were subjected

to the following treatments.• Solar disinfection• Chlorination• Using Silver nitrate• Combination of the above method.

Solar DisinfectionSolar disinfection is a process where in

microbes are destroyed through temperature andultra violet radiation provided by the fun.

Water is filled either in a clean transparent orpainted (Black) bottle oxygenated by shaking,followed by topping up. It is placed in the horizontalportion on tope exposed to direct sunlight for about

sis hours. Such an exposure increases thetemperature of water and also gives an extendeddose of solar radiation killing the microbes.

ChlorinationChlorination is one of the most reliable

methods of disinfecting drinking water. In thismethod the calculated amount of chlorine is addedto one litre of water sample for a specified tune andthereafter tested for the coliform counts.

Silver NitrateSilver nitrate is very small doses of 0.05 to

0.1 mg/l helps in disinfecting the drinking water.Silver nitrate in smaller doses does not impart anytaste, odour or produces any harmful effect onhuman body.

Combination of the above methodsIn order to investigate the effectiveness of the

treatment methods following combinations weretried.a) Chlorine + Solar disinfectionb) Silver nitrate + Solar disinfection.

Tables 2,3 & 4 presents the details of coliformcounts of the above specified treatments.

Table 1 : Experimental Results of Physical, Chemical & Biological Parameters

Sample Date of Expt Turbidity pH Do Hardness Chloride Alkalinity AcidityNTU mg/l of mg/l mg/l mg/l of mg/l of

CaCO3 CaCO3

1. Banashankari 14/08/05 4.6 7 7.8 56 13.96 86 06

2. MSRIT 17/01/06 6.3 8.4 7.7 22 16 30 083. Shivajinagar 21/11/05 8.3 8.11 8 58 13.2 40 064. Vijayanagar 18/01/06 11.9 7 7.7 58 21.3 46 125. Vidyaranyapura 12/12/05 7.3 8 8.1 46 12 18 14

Table 2: Coliform Count (At room temperature)

Sample Date of Collection Date of experiment Coliform Count/100ml (Average of 3 tests)Chlorination Silver Nitrate

1. Banashankari 20/10/05 17/05/06 0 02. MSRIT 25/10/05 17/05/06 0 03. Shivajinagar 25/10/05 17/05/06 0 04. Vijayanagar 25/10/05 17/05/06 0 05. Vidyaranyapura 28/10/05 17/05/06 0 0

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Careful study of Table 2 depicts thatchlorination and Silver nitrate in very small dosagesare very effective even at room conditions, justifyingtheir selection.

Detailed study of Table 3 indicates that solardisinfection using a transparent bottle is not veryeffective in reducing the coliform counts. However,addition of chlorine and silver nitrate have provedto be highly effective, further strengthening theirselection as disinfectants.

Finally from Table 4, it can be seen that solardisinfection using a black painted bottle has yieldedin a more effective disinfection, the coliform countshave very significant, reduced. The reason beingthat a black bottle or body absorbs more heat, whichenables in destroying the bacteria. In the presentinvestigations is was observed that the watertemperature in the bottles recorded a temperaturearound 500 C.

It is also very interesting of disinfection tonote that the chlorination method has establishedits supremacy.

ConclusionsRainwater collection is easy and economicalboth in rural and urban areas.Rainwater harvested during Oct 2005, tested tillMay 2006 without much changes in physicalproperties like colour, odour & turbidity, inspiteof the fact that they were from various sourcesand stored in normal food grade plasticcontainers.All the treatment methods suggested are highlyeffective in reducing the microbiologicalcontamination and also viable both at rural andurban levels.Rainwater harvesting and its treatment isaffordable by individuals and will be highlyuseful in drought prone areas.

FutureIt is suggested that similar investigations are

made on a number of samples collected fromdifferent places, stored under different conditions.

Table 3 : Coliform Count (Solar disinfection using transparent bottle)

Sample Date of Date of Expt Coliform count / 100mlCollection Transparent Bottle Chlorination Silver nitrate

(Average of 3 tests)1. Banashankari 20/10/05 17/03/06 40 0 02. MSRIT 25/10/05 24/03/06 38 0 03. Shivajinagar 25/10/05 02/04/06 40 0 04. Vijayanagar 25/10/05 15/04/06 35 0 05. Vidyaranyapura 25/10/05 21/04/06 28 0 0

Table 4 : Coliform Count (Solar Disinfection using black painted bottle)

Sample Date of Date of Expt. Coliform Count / 100 ml (Average of 3 tests)Collection Black Bottle Chlorination

1. Banashankari 20/10/05 17/03/06 2 02. MSRIT 25/10/05 24/03/06 2 03. Shivajinagar 25/10/05 02/04/06 3 04. Vijayanagar 25/10/05 15/04/06 2 05. Vidyaranyapura 28/10/05 21/04/06 0 0

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AcknowledgementThe author wishes to thank the management

of M.S.Ramaiah Institute of Technology, Bangalore560054 for all the encouragements & inspirationprovided for the study. Also many thanks are due toMr.Sunil Hegde, Mr.Anantha Padmanabha &Mr.Vinay Final Year B.E. Students for their helpduring the course of the experimental investigations.

References :1. Bell, F.A.Jr, D.L.Jerry, J.K.Smoth, and

S.C.Lynch, Studies on home water treatmentsystems. Jr.Am water works Assoc. 75:104-107-1984.

2. Davies C.M., and Evison L M “Sunlight & thesurvival of entropic bacteria in natural waterJournal of applied Bacteriology 7, 265-274-1991.

3. Drinking water standards, www.epa.gov/safewater/md.html.

4. I.S. 10500:1991 “Drinking Water Standards”.5. Jalbottt R “Rural water supply and Sanitation

program in India – Goals, roles & innovation.

Proe. 23rd WEDC Conf. Sep 1-5 1997, DurbanS.Africa.

6. Sharma S.K. and Jain S.K, Proceedings of theInternational Conference on Management ofDrinking water resources – central leatherResearch Institute. Anna University & TamilNadu Water supply & Drainage, Board,Chennai, 1997, pp129-138.

7. Wegelin M & Sommer B, Solar waterdisinfections (SODIS) – Destines for worldwide use. Water lines, Vol 16, No.3, ITPublications, London 1998.

8. Winter bottom, Daniel “Rainwater Harvesting,An ancient technology – cisterns inreconsidered, Landscape Architecture”, April.2000 pp 42-46.

9. White G.C, Hand Book of chlorination &Alternative Disinfectants, Johns Wiley & Sons,Inc, New York 1999.

10. Wolfe R.L., 1990, “Ultraviolet Disinfection ofPossible water” Env.Sci and Technology 24(6),768-773, 1990.

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1.1 Water is an essential natural resource forsustaining life and environment. The available waterresources are under pressure due to increasingdemands and the time is not far when water, whichwe have always thought to be available in abundanceand free gift of nature, will become a scarcecommodity. Conservation and preservation of waterresources is urgently required to be done. Watermanagement has always been practiced in ourcommunities since ancient times, but today this hasto be done on priority basis.

1.2 India’s population has recently crossed the onebillion mark, with an ever-increasing population, ourcountry faces a serious threat to the management ofher water resources as the gap between demand andsupply widens.

2.1 In our villages and cities, down the ages, peoplehave developed a wide array of techniques to harvestrainwater, which are simple, efficient and costeffective. There is a tendency to ignore thesetraditional water-harvesting systems. We shoulddraw upon the wisdom of our ancient life sustainingsystems and through better management, conserveour precious water resources.

2.2 Harvesting of rainwater is of utmost importantand the ministry of water resources is embarking onsuch programme. A judicious mix of ancientknowledge, modern technology, public and privateinvestment and above all, people’s participation willgo a long way in reviving and strengthening waterharvesting practices through out the country.

3.1 Ground Water Resources: - Annuallyreplenishable resources are assessed as 432 billioncubic meters (BCM)

5. Rain Water Harvesting and Ground Water Recharge

*Madhaorao Bajirao Deshmukh

*B.Sc., B.E. (Hon), AMICE (USA), Ex- Superintending Engineer, 54, Tatya Tope Nagar, Nagpur

By adopting water harvesting, an additional 160BCM shall be available for use.

3.2 Ground water level in some areas are falling atthe rate of one meter per year and rising in someother areas at the same rate.

You can capture and recharge 650000 liters ofrainwater from a 100-sq. meters size rooftop andmeet drinking and domestic water requirement offamily of four for 160 days.

The number of wells and borewells forirrigation in the country has increased five fold to175 lacks during past fifty years.There are 25 to 30 lack wells and borewells fordrinking, domestic and industrial uses.More than 80% of rural and 50% of urban, industrialand irrigation water requirement in the country aremet from ground water.

3.3 Causes Of Fall In Ground Water Levels• Over exploitation or excessive pumpage eitherlocally or over large areas to meet increasing waterdemands.• Non-availability of other sources of water.Therefore, sole dependence is on ground water.• Unreliability of municipal water supplies bothin terms of quantity and timings, driving people tothere own sources.• Disuse of ancient means of water conservationlike village ponds, baolis, percolation tanks andtherefore, higher pressure on ground waterdevelopment.

3.4 Effects Of Over Exploitation Of GroundWater Resources• Drastic fall in water levels in some area• Drying up wells/ borewells• Enhanced use of energy

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• Deterioration in ground water quality• Ingress of sea water in coastal areas.

4.0 Method And Techniques Of Rain WaterHarvesting• Roof – top rain water harvesting and itsrecharge to underground through existing wells andborewells or by constructing new wells, borewells,shafts etc.• Capturing and recharging city storm water runoff through wells, shafts, storm water drains.• Harnessing run off in the catchment byconstructing structures such as gabions, check dams,bhandaras, percolation trenches, sub-surface dykesetc.• Recharging treated and industrial affluentunderground by using it for direct irrigation orthrough ponds, basins or wells etc.

5.0 Objective Of Rain Water Harvesting• Restore supplies from the aquifers depleted dueto over exploitation• Improve supplies from aquifers lackingadequate recharge.• Store excess water for use at subsequent times.• Improve physical and chemical quality ofground water• Reduced storm water run off and soil erosion• Prevent salinity ingress in coastal areas.• Increase hydrostatic pressure to prevent/ stopland subsidence.• Recycle urban and industrial wastewater etc.• Rehabilitate the existing traditional waterharvesting structure like village ponds, percolationtanks, baolis, tanks, etc• With minor scientific modifications andredesigning, convert the traditional water harvestingstructure into ground water recharge facilities.• Use the existing defunct wells and borewellsafter cleaning and also the operational wells asrecharge structures.

6.0 Benefits Of Rain Water Harvesting• Rise in ground water levels in water• Increased availability of water from wells• Prevent decline in water levels• Reduction in the use of energy for pumpingwater and consequently the costs.• Reduction in flood hazard and soil erosion

• Benefiting in the water quality• Arresting sea water ingress• Assuring sustainability of the ground waterabstraction sources and consequently the village andtown water supply system• Mitigating the effect of droughts and achievingdrought proofing• Reviving the dying traditional water harvestingstructures and their rehabilitation as rechargestructures.• Effective use of lack of defunct wells andtubwells as recharge structure• Up gradation of social and environmental statusetc.

7.0 Proposed Policy Measures For Rain WaterHarvesting• Provides at least one roof-top rain waterharvesting structure for every 200sq. meters plot inurban areas.• Revive/ rehabilitation all village ponds• Subject to technical feasibility, provides at leastone check dam / KT weir / Sub- surface dyke ineach streamlet with catchments of 1 to 3 sq. km.• Provide all drinking water wells with a rechargestructure• Ban construction of irrigation wells / tubewellswithin a distance of 200 m or less (depending onscientific criteria) of the drinking water supply well.

8.0 Success Stories Of MAHARASHTRA• In Yaval taluka, Jalgaon District, Sixpercolation tanks, two recharge shafts and oneinjection well were constructed- A total of about 546ha area benefited• In Amravati District, three percolation tanksand ten cement plugs benefiting an area of 280 haand 100 ha respectively have been constructed- risein water level up to 10 meters recorded.• Experiments of catchments treatment carriedout at Adgaon and Palaswadi in Aurangabad,Ralegaon Siddhi in Ahmednagar and Naigaon inPune by Shri Anna Hazare - effort have led to revivalof streamlets and enhanced availability of groundwater in the water shed.

9.0 Proposed Strategy• Organize Mass Awareness Programmesinvolving district administration and NGOs to

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educate in different sections of users and to makethe programme demand oriented.• Roof-Top rain water harvesting and its rechargeunderground through more than two lack existingbut defunct drinking water and irrigation wells, orby constructing new wells, borewells, Shafts,spreading basins etc.• Make roof-top rain water harvesting andrecharge mandatory in all urban dwellings.• Capturing city storm water runoff andrecharging it through wells, shafts, spreading basins,storms and water drains etc.• Harnessing run off in catchments byconstructing structures such as gabions, check dams,bhandaras, percolation trenches, bus-surface dykesetc.• Impounding surface run from villagecatchments and water shed(s) in village ponds andpercolation tanks.• Rehabilitation all ancient rain water harvestingstructures.• Invoke legal provision, if and when required,to regulate indiscriminate boring of wells and tomake the installation of recharge facilities mandatory• Constitute water user Association (WUA) orvillage Beneficiary Groups (VBG) NGOs toorganize the constitution of these bodies. The WUA/VBG and NGOs to be associated with the projectright from the concept to completion stages.• For expanding further scope of work, the

industrial houses to be invited to participate in thework and adopt towns and villages and providefinancial support.• Government organizations to act as facilitatorsand provide technical and financial support forcreating the demonstration facilities etc.

10.0 Future Action Plans• Prepare national and state level waterharvesting perspective plans.• Develop plans and implement roof-top rainwater harvesting measures using 1,00,000 wells(existing, defunct and or operative wells to be usedin the first instance)• Provide rural drinking water wells withrecharge facilities- cover 1,00,000 wells• Harvest and recharge city storm water in 100towns• Revive and rehabilitate 1, 000 dying villageponds.• Design and construct 200 percolation tanks,5000 check dams/ bhandaras and 1,000 sub surfacedykes.• Recycle secondary treated urban waste waterthrough aquifers at five centers.• Identify potential aquifers in drought proneareas and declare these apart as “Ground WaterSanctuaries”

Ref: - CENTRAL GROUND WATER BOARD-MINISTRY OF WATER RESOURCES.

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Introduction :India’s total land area is 3287263 Sqkm. The

cultivated land is 55.7% i.e., 183.09 million hectors.Average annual rainfall is 117 Cm; average monsoonrainfall is 55 Cm. The occupation of about 70% ofpeople in India is agriculture. The population ofIndia is fed on the food production of the country.Main source of water in this country is rainfallduring monsoon season. The rainfall mainlyconfined in the months from June to September. Butit is not regular and erratic with respect to both timeand place. Now a days drought and floods are thesever hazards in different parts of our country. Therequirement of agricultural produce is expected torise steeply by 2025.Hence India must concentrateon increasing area under irrigation and improvingthe productivity of both land and water to meet theneeds of the population. The demand of waterincreasing due to several factors such as increase inpopulation growth, which has led to a situation inwhich water has become a scarce resource. Henceit is very essential to harvest rainwater during rainyseason. Rainwater harvesting is the intentionalcollection of rain water from a surface and itssubsequent storage in order to supply water duringthe time of demand. Rain water harvesting isessential in view of the fact that rainfall, which is asource of fresh water, occurs in very short spellsand runs off as a waste unless arrangements aremade for its storing.

Main source of irrigation development aredams and canals. Other option are water harvestingstructure such as for ground water development,surface minor irrigation systems, watershed

development etc. Rainwater harvesting is usuallyclassified into two types (i) harvesting foragriculture (irrigation) needs and (ii) harvesting fordomestic and other needs. For irrigation needs therainwater can be harvested during rainy season byconstructing any of the following structures.1. Major storage reservoir2. Medium storage reservoir3. Minor storage tanks4. Watershed development Structures, likeCheck dams, percolation tanks, Sunken gully pitsetc.,

Looking in to the rainfall trends in past fortyyears it is felt that rain water above 75% P.L. shouldbe stored for beneficial use during droughts / lowrainfall year. In this paper it is proposed to constructRain Water Harvesting Tanks for the beneficial useof water for supplementing minor irrigation tanksduring drought years. Rain Water Harvesting isbeing promoted extensively in India, particularlyin the Southern States.

Need for Rain Water Harvesting Tanks :Since rivers occasionally swells, hence some

countries have built oversized capacity reservoirsto store surplus water which will other wise bewasted in to sea. For example, Egypt had builtOswan Dam to store water about five times the yieldavailable in Nile River. During droughts they aresuccessfully irrigating lands so that the country isnot vulnerable by famine. In most of the areas ofsemi-arid region yearly rainfall is below the normalfor continuous two to three years followed by anormal rainfall year. The year wise monsoon rainfall

6. Rain Water Harvesting Tanks for Supplementing Minor IrrigationTanks during Drought

* Mohd. Mahboob Hussain

* Deputy Executive Engineer, Medium Irrigation, I & C.A.D.Department, Govt. of A.P., Hyderabad


23

for some of the rain-gauge stations of Ranga ReddyDistrict in Andhra Pradesh are shown in annexure-I and graph enclosed showing rainfall variation forlast 40 years indicates that lot of water above 75%P.L .is wasted. More over from rainfall graphs itcan be seen that there are number of years whenthere is rainfall more than 75 % P.L followed by alow rainfall year. From graph of Monsoon rainfallversus year for Medchal R.G.S, the followingconclusions are drawn.

(i) In the year 1967 there is excess rainfall over75% P.L. followed by a normal rainfall year1968 and a low rainfall year in 1969.

(ii) In the year 1971 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 1972.

(iii) In the year 1974 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 1975.

(iv) In the year 1976 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 1977.

(v) In the year 1978 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 1979.

(vi) In the year 1983 there is flood followed by anormal rainfall year of 1984 and a low rainfallyear of 1985.

(vii) In the year 1990 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 1991.

(viii) In the year 1996 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 1997.

(ix) In the year 2000 the rainfall is much higherthan 75% P.L. followed by low rainfall yearof 2001.

From the above it can be stated that the waterabove 75% P.L. can be stored in the proposed RainWater Harvesting Tanks and used in the low rainfallyears. Presently any irrigation project is design toutilize water out of the available 75% dependableyield. Water has to be harvested, preserved andutilized for beneficial used, as it is becoming a scarce

natural resource. Hence all water over and above75% dependable yield is wasted in to sea. Sincerainfall is a natural phenomenon, we do not knowwhen and in which year rainfall will be above 75%P.L., hence it is the need of the hour to harvest Rainwater above 75% P.L. also and to utilize during thedrought / low rainfall year. It is proposed to constructRain Water Harvesting Tanks without any canalsystem with a sluice to letdown water in the downstream for existing minor irrigation tanks.

For one R.G.S (i.e., TANDUR) the year wisetotal yield available for one of the subgroup having20 Sq.Miles for 40 years have been calculated. Theyield available @ 75 % PL also has been calculatedusing strange’s table which works out to 255.64Mcft. The surplus yield available after deductingthe yield @ 75 % PL from the total yield is alsocalculated year wise. Statement showing the abovevalues year wise are presented in annexure- IIenclosed. From the statement it is observed that for30 years there is surplus yield available. Themaximum surplus yield is 801.20 MCft. Theaverage of surplus yield for 30 years is 267.495Mcft, but where as the 75% dependable yield is255.64 Mcft. The average of surplus yield is slightlyhigher than the yield available at 75% dependability.Since every year the surplus yield may not beavailable so much, hence it is proposed to utilize atleast 50% of the yield available at 75%dependability duly constructing Rain WaterHarvesting Tanks. In the statement minus valuesindicates that the yield available is below the 75%PL yield for ten years out of 40 years. Hence thereis scope for storing this surplus yield in the proposedRain Water Harvesting Tanks.

More over sometimes heavy rainfall occursin one single month followed by a dry spell of 20 to30 days. In such case also this excess water due toheavy rainfall can be stored in Rain WaterHarvesting Tanks and released for existing minorirrigation tanks during dry spell so that crops canbe grown successfully.

The World Banks has published a report“India’s Water Economy: Bracing for a turbulentfuture”. In this report it is highlighted that India’sstorage capacity of 200m3 per person is too little, as

24

compared to over 5000 m3 per person in U.S.A.and Australia, and 1000 m3 per person in Mexicoand China. It is also highlighted that the need forstorages in India will be even more in the postclimate change scenario. In India the poverty inirrigated districts is one third of that in unirrigateddistricts. Hence the proposed Rain Water HarvestingTanks will increase storage capacity per person inIndia.

Methodology for Proposing Rain WaterHarvesting Tanks :

In a sub-group of a given sub-basin of a riverbasin there may be few minor irrigation tanks, checkdams and percolation tanks which together mayutilize 75 % dependable yield. Whenever there ishigh rainfall above 75% P.L. in the catchment, thewater go waste down stream and ultimately joinssea. We may not be able to know how much surpluswater (above 75% P.L.) a sub-group catchmentyields. Hence it is proposed to utilize at least 50 %of the water utilization of that of existing tanksdesigned to utilize 75 % dependable water, so thatif there is failure of monsoon next year we can makeuse of this water for irrigation and avoid drought.The following sketch shows probable locations ofRain Water Harvesting Tanks in a given sub-group.The Rain Water Harvesting Tanks should be locatedin the initial reaches of streams, so that the storedwater can be utilized for filling the minor irrigationtanks when there is scanty rainfall and hence cropscan be grown successfully.

Design of Rain Water Harvesting Tanks :Select the site of Rain Water Harvesting Tanks

such that it can feed the minor irrigation tank

through natural stream with minimum conveyancelosses. The Rain Water Harvesting Tanks shouldessentially have a sluice and a surplus weir todispose off flood water. The sluice can be used tolet down water to the down stream existing minorirrigation tanks. The design procedure of minorirrigation tank can be adopted for design of RainWater Harvesting Tanks. The capacity of each RainWater Harvesting Tank can be fixed based on thenumber of tanks to be taken up as Rain WaterHarvesting Tanks duly utilizing at least 50 % of theutilization of that of minor irrigation tank designedfor 75 % dependable water. Eg: - In a given sub-group if the 75% dependable water is 100 M.cft.and the existing utilization is 80 M.cft. underexisting minor irrigation tanks. Rain WaterHarvesting Tanks should be design to hold 40 M.cft.of water, which is 50% of present utilization. Tostore 40 M.cft. of water, now propose 4 tanks ofeach 10 M.cft. live capacity in the upper reaches ofstreams so that this water can be utilized duringdroughts / low rainfall year.

Plan of operation for Rain Water HarvestingTanks :

Once these Rain Water Harvesting Tanks areconstructed, the sluices should be kept open so thatwhen it rains the water will flow down to the existingminor irrigation tanks to fill them up to their fulltank level in the monsoon. When the minor irrigationtanks are filled up the sluices of Rain WaterHarvesting Tanks should be closed so that watercan be stored in these Rain Water Harvesting Tanks.Then depending up on the number of fillingsrequired ( as per design ) again water can be releasedto lower existing minor irrigation tanks for their fullutilization as per hydrological clearance given . Nowclose the sluices of Rain Water Harvesting Tanksand store water up to full tank level. If there areheavy rains again the surplus water willautomatically flow down through surplus weir. Nextyear when monsoon are late, some quantity of waterfrom these Rain Water Harvesting Tank can bereleased through sluices to the existing minorirrigation tanks so that farmers can take up landpreparation and sowing can be done in time. Even

25

if the monsoon fails the remaining water also can bereleased to down stream tanks so that the crops canbe grown successfully. In a year when total rainfallis less than normal, these Rain Water HarvestingTanks can be kept empty.

Conclusions :(1) The concept of Rain Water Harvesting Tank

is to store water during excess rainfall year(above 75% P.L.) and to utilize during drought/scanty rain fall year.

(2) Since Rain Water Harvesting Tanks aredesigned to store surplus water over andabove 75% P.L yield, there will not be anyeffect on existing minor irrigation system.

(3) Success rate of existing minor irrigation tankscan be ensured by regulation of water fromRain Water Harvesting Tanks, thus utilizingwater optimally.

(4) Generally minor irrigation tanks are designedfor 150% irrigation intensity. Because ofproposed Rain Water Harvesting Tanks inupstream by storing surplus water, theintensity of irrigation can be increased to200% by supplying water for Rabi crops byvirtue of which food production can beenhanced.

(5) These Rain Water Harvesting Tank can serveas percolation tank in upper reaches ofcatchments to improve ground water table,as there will be some dead storage below silllevel of sluice of that tank.

(6) Because of construction of Rain WaterHarvesting Tanks the loss due to flooddamages can be minimized.

(7) Wastage of heavy surplus water in to sea canbe minimized.

(8) Rain Water Harvesting Tanks also will be verymuch useful for flora and fauna formaintaining ecology of that area.

(9) There will be soil conservation in the upperreaches of the catchment because ofconstruction of Rain Water Harvesting Tanks.

(10) There is a need to workout surplus yields forevery year for each Rain Gage Stations andprepare model for storing water in Rain WaterHarvesting Tanks to utilize surplus wateroptimally.

(11) As water is becoming scarce natural resource,the cost of construction of Rain WaterHarvesting tanks should not come into way.

(12) There is a need to formulate a coherent policyor strategy towards strengthening extensionand technical support for Rain WaterHarvesting Tanks for crop production.

References :(1) “Innovative participatory technologies for

water shed development in drought proneareas of India” by Sri. T. Hanmanth Rao,Consultant of united nation.

(2) “Hand book for planning water shedmanagement works”, Government of India,Ministry of water resources, CWC,December, 2000.

(3) Paper on “Irrigation development in India”by Sri. Uddhao Wankede published inproceedings of National Seminar on “Irrigation development India” held from 9-10 October 2004 hosted by the Institution ofEngineers (India), Nagpur local Center.

(4) Irrigation manual by Illys.(5) “Rain water harvesting – a case study in a

collage campus in Mysore”, by Sri. M. R.YADUPATHI PUTTY & Sri. P.RAJE URS,Dept. of civil engineering, National Instituteof Engineering, Mysore published inHydrology Journal of Indian Association ofHydrologist volume 28, November 3-4,September – December 2005.

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ANNEXURE - IMonsoon Rainfall ( in mm ) of different Rain guage stations of R.R. District in A.P

S.No Year Medchal Tandur Himayat Sagar1 1960 N/A N/A 551.22 1961 N/A 909.1 571.23 1962 N/A 1063.6 8564 1963 759.9 942.8 751.85 1964 710.3 751.5 710.86 1965 671.9 663.6 7967 1966 468.2 493.1 689.48 1967 804.2 670.2 865.49 1968 663.4 652.3 440.910 1969 600.9 684.4 452.411 1970 754.9 992.9 84212 1971 797.7 459.3 497.613 1972 547.8 454 221.714 1973 957.6 1097 633.515 1974 784.4 850 614.416 1975 566.7 1116.5 1689.617 1976 720.1 725.1 906.818 1977 584.1 480.8 568.519 1978 783.3 1216.6 1009.720 1979 440.3 585.2 564.621 1980 845.2 650.5 577.622 1981 1102.8 711.9 660.123 1982 862.8 665.9 564.624 1983 1858.5 1036.6 793.225 1984 673.7 651.6 595.626 1985 563.1 822.6 550.927 1986 445.9 645 58628 1987 604.8 853.8 795.529 1988 933.4 961.1 741.430 1989 845.3 864.4 711.531 1990 760.4 1173 721.632 1991 624.8 767.4 393.433 1992 645.8 795.8 611.934 1993 767.5 697.2 479.835 1994 787.2 479.8 598.736 1995 899.9 790.8 107737 1996 775.8 758.6 803.738 1997 533.6 648.3 514.439 1998 988.6 1342.1 983.540 1999 701.3 670.7 540.841 2000 791.3 861.9 N/A 42 2001 589.6 N/A N/A 43 2002 629.4 N/A N/A

N/A –Not Available.

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Annexure- IIStatement showing the surplus yield beyond 75% dependability

No. Year Monsoon Yield per Total Yeild Yeild Surplus % of SurplusRainfall Sq.miles from Available Yeild Yeild beyondin mm in MCft subgroup @ 75% PL 75 % PL

C.A ( 20 Sqm)1 1961 909.1 27.25 545 255.64 289.36 113.192 1962 1063.6 38.566 771.32 255.64 515.68 201.723 1963 942.8 29.53 590.6 255.64 334.96 131.034 1964 751.5 17.742 354.84 255.64 99.2 38.85 1965 663.6 13.317 266.34 255.64 10.7 4.196 1966 493.1 6.479 129.58 255.64 -126.06 -49.317 1967 670.2 13.628 272.56 255.64 16.92 6.628 1968 652.3 12.783 255.66 255.64 0.02 0.019 1969 684.4 14.297 285.94 255.64 30.3 11.8510 1970 992.9 33.148 662.96 255.64 407.32 159.3311 1971 459.3 5.417 108.34 255.64 -147.3 -57.6212 1972 454 5.255 105.1 255.64 -150.54 -58.8913 1973 1097 41.248 824.96 255.64 569.32 222.714 1974 850 23.447 468.94 255.64 213.3 83.4415 1975 1116.5 42.841 856.82 255.64 601.18 235.1716 1976 725.1 16.322 326.44 255.64 70.8 27.717 1977 480.8 6.079 121.58 255.64 -134.06 -52.4418 1978 1216.6 51.618 1032.36 255.64 776.72 303.8319 1979 585.2 9.872 197.44 255.64 -58.2 -22.7720 1980 650.5 12.698 253.96 255.64 -1.68 -0.6621 1981 711.9 15.647 312.94 255.64 57.3 22.4122 1982 665.9 13.426 268.52 255.64 12.88 5.0423 1983 1036.6 36.404 728.08 255.64 472.44 184.8124 1984 651.6 12.75 255 255.64 -0.64 -0.2525 1985 822.6 21.767 435.34 255.64 179.7 70.2926 1986 645 12.437 248.74 255.64 -6.9 -2.727 1987 853.8 23.691 473.82 255.64 218.18 85.3528 1988 961.1 30.863 617.26 255.64 361.62 141.4629 1989 864.4 24.37 487.4 255.64 231.76 90.6630 1990 1173 47.745 954.9 255.64 699.26 273.5331 1991 767.4 18.627 372.54 255.64 116.9 45.7332 1992 795.8 20.213 404.26 255.64 148.62 58.1433 1993 697.2 27.448 548.96 255.64 293.32 114.7434 1994 479.8 6.048 120.96 255.64 -134.68 -52.6835 1995 790.8 19.926 398.52 255.64 142.88 55.8936 1996 758.6 18.139 362.78 255.64 107.14 41.9137 1997 648.3 12.593 251.86 255.64 -3.78 -1.4838 1998 1342.1 52.838 1056.76 255.64 801.12 313.3839 1999 670.7 13.652 273.04 255.64 17.4 6.8140 2000 861.9 24.21 484.2 255.64 228.56 89.41

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29

30

INTRODUCTION :Water is the most important resource of the

entire society as a whole, since no life is possiblewithout water. As water, being a limited resource,its efficient use is basic to the survival of the everincreasing population of the world. In India, theground water is mainly used for drinking andagricultural purposes. About 85% of drinking wateris available through dug well, bore well, filter pointand tube well etc. The per-capital availability ofwater at national level has reduced from about 5,177m3 in the year 1951 to present level of 1,869 m3.In view of this, water management is very criticalfor the growth and development of any economy,more so in a large country like India which isendowed with many large rivers, lakes and wellsthat need to be conserved, better managed, rechargedand channellised for meeting the ever growingrequirement of agriculture, industrial and urbangrowth. Moreover exploitation of ground water hasbeen taken up by millions of individual farmersmostly in regions where surface water is eitherscarce or absent to meet their dire water needs.Although this has lead to local depletion or declineof ground water levels causing serious concern aboutrainwater harvesting & the need to recharge groundwater. The quantum of ground water so far harnessedis one third of the replenishable ground water of431 km3 a year. In the comprehensive strategyneeded for the conservation and development ofwater resources, several factors are to be kept inview. These include the availability of water, itsquality, location, distribution and variation in itsoccurrence, climatic conditions, nature of the soil,competing demands & Socio-economic conditions.In dealing with each of these, every effort must bemade to make the best use of water for the survivalof human life, animal and plant life.

WATER AVAILABILITY :India receives precipitation (including

snowfall & rain) of around 4,000 billion cubicmetres (BCM), only 1,869 BCM is accessible water,of which India uses barely a third. Nearly 1,179BCM of water drains in to the sea. Region, whoseyearly renewable freshwater availability is below1,700 m3/ person is called as the water stress region.And the region whose yearly availability falls below1,000 m3 / person is termed as water scarcity region.But national figure of annual average per capitawater availability is 2,464m3. It shows that thecountry is not in the water stress range so far.However in some regions per capita availability isas low as 411m3. (Kanyakumari, Pennar, Kutchh,Kathiawar, Krishna basin, etc. )

The run-off which is about 215 MHM needsto be arrested by making proper planning on microlevel as well macro level. Microlevel means waterconservation schemes of the state governmentswhich is to be implemented in every village. But onmacro level, a large chunk of water must be arrestedby programme like national river – linking.Availability and utilization of water in India isshown in table No.1 & Fig. No.1.

Table No. 1No. Item Quantity

(Cu.Kms.)1. Annual precipitation volume

(including snowfall) 4,0002. Average annual potential flow

in rivers 1,8693. Per Capita Water availability

(1997) 1,9674. Estimated utilizable water resources 1,122

i) Surface water resources 690ii) Ground water resources 432

*Lect.in Civil Engg., Govt. Polytechnic, Nanded **Lect.in Civil Engg., Govt. Polytechnic, Washim

7. Rain Water Harvesting and Recharging Ground Water

*R. K. Parghane *S. P. Kulkarni **A.W. Dhawale


31

The average annual precipitation is 400 million Hectare Metre (MHM)

Evaporates 70 MHM

Percolates 115 MHM

Run - off 215 MHM

Moist soils 65 MHM

Enters into the ground water table 50 MHM

Fig. 1 : Details of precipitation water

RAINWATER HARVESTING AND ITSTECHNIQUES :

Rain is the ultimate source of fresh waterwith the ground area around houses and buildingsbeing cemented, rain water which run–off fromterraces and roofs was draining into low-lying areasand percolating into the soil and causing floods elsewhere.

Rainwater Harvesting is a system by which,rainwater that collects on the roofs and the areaaround buildings is directed into open wells, borewells, tube wells through a filter tank or in to apercolation chamber, built specifically to serve thepurpose. The rain water can be stored in tanks andcan be recharged in to the ground to improve groundwater storage.

The storage of rainwater on surface is atraditional technique and the structures used wereunderground tanks, ponds, check dams, percolationwells, weirs etc. Recharge to ground water is a newconcept of rainwater harvesting.There are following three techniques of rainwaterharvesting.a) Storing rain water for direct use.b) Recharging ground water aquifers, from roof

top run off.c) Recharging ground water aquifers with runoff

from ground area.

The techniques of rainwater harvesting

have been depicted in the Fig.No.2, Fig.No.3, Fig.No.4.

Fig. No. 2 Roof Top Rainwater Harvesting

Fig. No. 3 Recharging of Bore well

32

WHY RAINWATER HARVESTING ?To meet our water demand, we entirely

depend upon rivers, lakes & ground water. Howeverthe rain is the ultimate source that feeds all thesesources. The rainfall is highly seasonal and occursover a short rainy season with a very large dryperiod. As a result, there is a progressive decreasein the ground water level. Hence, it should beadmitted that rain water harvesting is essentialbecause.i) Surface water is inadequate to meet our demand

and we have to mostly depend on ground water.ii) Due to rapid urbanization population growth

and industrialization, improved sanitation,living standard, infiltration of rain water intothe sub-soil has decreased drastically andrecharging of ground water has diminished.

iii) Over exploitation of ground water results in to-i) Ground water depletion.ii) Drying up of wells / bore wells.iii) Enhance use of energy.iv) Ingress of sea water in coastal area.

It is now alarming to seriously considerabout conserving water by harvesting and managingthis natural resource by artificially recharging thesystem.

HOW MUCH RAIN WATER CAN BEHARVESTED FROM ROOF TOP ?

The estimation of water available from topof roof (flat terrace) is worked out by multiplyingthe roof area with normal rainfall data for monsoonperiod. Total quantity of rain water available fromroof top to be used for harvesting is about 70% to90%, due to losses like evaporation, absorption,leakages etc.

Following table shows how much roofwater can be harvested by considering 80%efficiency and according to roof top surface areas.Roof top Area (Sq.m)

Considering hypothetical case followingcalculations shows as to how much rain water canbe harvested.

Consider a building with a flat terrier area =125 Sq.m.Average annual gainful in the area is say 1000mm (40 inch)Suppose, there is no loss of water from theterrace floor, then in one year, there will berainwater on the terrace floor to a height of1000mm.Height of rainfall = 1000 mm, Volume ofrainfall = 125 x 1000= 1,25,000 litresAssuming that only 80% water harvested.Volume of water harvested = 1,00,000 litres.A family of four needs 87,600 litres of waterper year. (@ 60 litres / person)

ARTIFICIAL GROUND WATERRECHARGE :

Optimum development and soundmanagement practices are vital to the sustained useof ground water. Ground water recharge may beincreased by conservation measures and artificialrecharge procedures. Artificial recharge to groundwater is a process by which the ground waterreservoir is augmented at a rate exceeding thatobtaining under natural conditions of replenishment.In general any man-made system or facility that addswater to an aquifer is an artificial recharge system.

Artificial recharge of ground water is,therefore, preferred and encouraged in the present

Fig. No. 4 Recharging of Open well

33

days, so as to augment the natural availableunderground yield for management of water supplysystems. Artificial recharging techniques is underintensive research and is being increasingly used inFrance, Israel, U.K. Germany etc.Ex.- Estimation ofi) The specific yield of the aquifer andii) The volume of Recharge during the wet season.Soln -Consider, the area of aquifer is 4 km2.Water pummeled out in lowering W.T. i.e.Volume of water drained by 6.8-4.8 = 2m is 2 M.m3

Total Volume of aquifer drained in lowering W.T.by 2 m

= Area x 2m= 4x106x2m3 = 8M.m3

Specific yield of aquifer S.Y.Specific yield, S.Y.= Volume of water drained x 100

Total volume of aquifer drained = 2Mm3 x 100 = 25%

8Mm3

During wet season, the W.T. rose by, 6-4.8= 1.2 m., Since 2m lowering of W.T. equals 2M.m3

of water, 1.2 m rise will equal to 1.2 M. m3 ofrecharge.

DIVERSION OF RUN OFF IN TO EXISTINGSURFACE BODIES

Construction activity in and around the city/town is resulting in the drying up of water bodiesand also reclamation of these tanks for conversionin to plots for houses has impacted urban hydrologyas under.1. Over consumption of water increases water

demand.2. More dependence on ground water use.3. Increase in run off, decline in well yields and

fall in water levels.4. Reduction in open soil surface area.

Reduction in infiltration and deterioration ofwater quality.

Roof Rain Fall (mm.) top Area 100 200 300 400 500 600 800 1000(Sq.m) Harvested Water from Roof Top (Cum) @ 80%

20 1.6 3.2 4.8 6.4 8.0 9.6 12.8 16.030 2.4 4.8 7.2 9.6 12.0 14.4 19.2 24.040 3.2 6.4 9.6 12.8 16.0 19.2 25.6 32.050 4.0 8.0 12.0 16.0 20.0 24.0 32.0 40.060 4.8 9.6 14.4 19.2 24.0 28.8 38.4 48.070 5.6 11.2 16.8 22.4 28.0 33.6 44.8 56.080 6.4 12.8 19.2 25.60 32.0 38.4 51.2 64.090 7.2 14.4 21.6 28.80 36.0 43.2 57.6 72.0100 8.0 16 24.0 32.0 40.0 48.0 64.0 80.0150 12.0 24 36.0 48.0 60.0 72.0 96.0 120.0200 16.0 32 48.0 64.0 80.0 96.0 128.0 160.0250 20.0 40 60.0 80.0 100.0 120.0 160.0 200.0300 24.0 48 72.0 96.0 120.0 144.00 192.0 240.0400 32.0 64 96.0 128.0 160.0 192.0 256.0 288.0500 40.0 80 120.0 160.0 200.0 240.0 320.0 400.01000 80 160 240 320 400 480 640.0 800.02000 160 320 480 640 800 960 1280.0 1600.0

34

RECHARGING OF UNDERGROUNDSTORAGE :

In order to store the surplus surface waterthe artificial surface reservoirs are constructed bybuilding dams, in the summer, artificial undergroundreservoirs are now-a-days developed by artificialrecharge for storing water underground.The development of such a reservoirs may beadvantageous as compared to the development of adam reservoir, because of the following reasons.i) Much pure water can be obtained from an

underground reservoir source.ii) No space is required for building such a

reservoir.iii) The cost of building such a reservoir by

recharging the aquifers may be considerablyless than the cost of the surface reservoirs.Moreover in an underground reservoir, theaquifer in which the water is stored shall itselfact as a distribution system for carrying thewater from one place to another, and as such,the necessity of constructing pipe lines orcanals (as is required in a surface reservoir)is completely eliminated.

iv) The water lost in evaporation from anunderground reservoir is much less than thewater lost from a surface reservoir.

v) The raising of the water table by artificialrecharge may help in building pressurebarriers to prevent sea water intrusion in thecoastal areas.

METHODS OF RECHARGING :The below mentioned methods are being

generally adopted for ground water recharging.1. Spreading Method.2. Recharge-well Method.3. Induced Infiltration Method.

1. Spreading Methods :This method consists in spreading the water

over the surfaces of permeable open land and pits,from where it directly infiltrates to rather shallowaquifers. In this method, the water is temporarilystored in shallow ditches or is spread over an openarea by constructing low earth dykes (calledpercolation bunds). The stored water, slowly andsteadily, percolates downward so as to join thenearby aquifers. The recharging rate depends upon

the permeability of the spread area and on the depthof water stored, and is generally less, say of the orderof 1.5m/day, though rates as high as 22m/day havebeen possible.

2. Recharge-well Methods :This method consists in injecting the water

in to bore holes called recharge wells. Dependingupon the favorable condition of surface, the wateris fed in to recharge wells by gravity or for increasingthe recharge rate, it may be pumped under pressure.The recharge wells used are just like ordinaryproduction wells. In fact the ordinary wells aremany a times could directly used for recharge duringthe off season, when the water is not required inuse. With this method high recharge rates can beobtained. This method is widely used in Israel.Moreover, this method may help in injecting waterin to the aquifers and also where it is most needed.To avoid clogging of the well screens, the waterused for recharging well should be free fromsuspended impurities.

3. Induced Infiltration Method :This method is sometimes used for recharge

is that of the induced infiltration which isaccomplished by increasing the water table gradientfrom a source of recharge. In this method, Renneytype wells are constructed near the river banks. Thepercolating water is collected in the well throughradial collectors and is then discharged in to a lowerlevel aquifer ‘B’ for storage as Shown in fig. No.5.This types of well construction is very common inFrance and is sometimes referred to as Frenchsystem of tapping underground water.

In addition to the above mentionedmethods, the recharge to ground water isaccomplished by using some of the structures area) Pits : The pits have been constructed about 3

metres deep & 1 to 2 metres wide filled withboulders, gravel and coarse sand such typesof ponds are constructed for rechargingshallow aquifer.

b) Trenches : Trenches are constructedsubjected to the availability of permeablestream at shallow depth. These trenches areback filled with filter materials. The trenchesmay be 0.5 to 1 metre wide, 1 to 1.5 meter

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increasing the available usable water by developingartificial rain technology. It is also of vitalimportance to conserve water by practicingeconomy and avoiding its wastage.

However ground water exploitation isinevitable especially urban areas. To curtail itsreduction, a strategy to implement the groundwaterrecharge, in a major way needs to be launched withconcerted efforts by various Non-Governmental andGovernmental agencies and the public at large, toincrease the water table and make the groundwaterresource, a reliable and sustainable source forsupplementing water supply needs. It is aboutbuilding our relationship with water and theenvironment. Harvest rain. Learn the prestigiousvalue of each rain drop.

REFERENCES :1. Dr. S.V.Dahasahasra, Dr. Y.B.Katpatal &

Dr.M.M.Mahajan, “National River –Linking” Journal of CE & CR, May – 2004,PP.26 – 34.

2. Eye Opener, “Rainwater Harvesting &Recharging Ground Water” enROUTE, JUL-DEC. 2005, Vol IX, PP. 16-17.

3. Kaushal Kishore, “Rainwater Harvesting”,CE & CR Journal, May 2004, PP.42-48.

4. Dr. Pranab Kumar Ghosh, “Rain WaterHarvesting – A Ray of Hope” Orissa Review,August 2004, pp. 38-40.

5. Dr. Gauhar Mahmood & SharshikantChaudhary “A Comprehensive WaterManagement Plan – A Case Study ofLakewood city, Harayana” Journal of IndianWater Works Association, July – Sept. 2004,pp. 219-228.Santosh Kumar Garg, “Hydrology and WaterResources Engineering” Khanna Publication.

Fig. No.5 Induced infiltration method ofrecharge

deep and 10 to 20 meters long depending onthe availability of water.

c) Dug wells : Existing dug wells may beutilized as recharge structure and water shouldbe allowed to pass through filter media beforestorage.

CONCLUSION -The proper conservation, maintenance and

careful use of water resources, along withdeveloping additional storages may considerablyreduce the chance of water famines for furthergenerations to come. In addition to these measures,it is necessary to find out means and ways for

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IntroductionTo meet the growing water supply demand, we

are depending maximum on surface water, which isstored in the form of lakes and reservoirs.Availability and storage of water in reservoirs andlakes depends ultimately on yearly rainfall. Ifrainfall is inadequate or if there is draughts forsuccessive years, surface water bodies get consumedand in such a case, we have no alternative than usingthe ground water. Therefore we must guard againstthe depletion or spoiling of our most valuableground water storage. Natural conservation andefficient use of this natural storage and at the sametime making arrangements for additional rechargeof ground water aquifer by one way or other, toreplenish the used ground water becomes ourresponsibility. We should make maximum use ofthe easily available normally wasted, localrenewable source of water that is rainwater. Theeffective way to store rainwater is by allowing it topercolate into ground by enriching ground waterstorage.

The artificial recharge to ground water aims ataugmentation of ground water reservoir bymodifying the natural movement of surface waterutilizing suitable civil construction techniques.Artificial recharge techniques normally address tofollowing issues –(i) To enhance the sustainable yield in areas whereover-development has depleted the aquifer(ii) Conservation and storage of excess surfacewater for future requirements, since theserequirements often changes within a season or aperiod.(iii) To improve the quality of existing ground waterthrough dilution.(iv) To remove bacteriological and other impuritiesfrom sewage and waste water so that water issuitable for re-use.

The basic purpose of artificial recharge ofground water is to restore supplies from aquifersdepleted due to excessive ground waterdevelopment.

1. Basic Requirements for Artificial RechargeProjects

The basic requirements for recharging theground water reservoir are:a) Source Water Availability

Before undertaking any artificial rechargeproject, it is a basic prerequisite to ascertain theavailability of source water for the purpose ofrecharging the ground water reservoir. Availabilityof non-committed surplus monsoon runoff in spaceand time can be assessed by analysing the monsoonrainfall pattern, its frequency, number of rainy daysand maximum rainfall in a day and its variation inspace and time.

b) Identification of AreaThe artificial recharge projects are site specific

and even the replication of the techniques fromsimilar areas are to be based on the local hydro-geological and hydrological environments. The firststep in planning the project is to demarcate the areaof recharge. The artificial recharge of ground wateris normally taken in following areas:1. Areas where ground water levels are decliningon regular basis.2. Areas where substantial amount of aquifer hasalready been de-saturated.3. Areas where availability of ground water isinadequate in lean months.4. Areas where salinity ingress is taking place.

2. Scientific InputsIn order to plan the artificial recharge schemes

following studies are needed.

8. Artificial Recharge of Aquifers in Urban Setup

*Mrs. Grace Selvarani

* Lecturer in Applied Mechanical Dept., M.H. Saboo & Siddik Polytechnic, Byculla, Mumbai - 8


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Hydro meteorological StudiesHydro meteorological Studies are undertaken

to decipher the rainfall pattern, evaporation lossesand climatological features. These can bring outthe extent of evaporation losses in post monsoonperiod which would be helpful in designing thestorages of particular capacity with a view to haveminimum evaporation losses. The data on rainfallintensity, number of rain-days, etc. help in decidingthe capacity and design of the artificial rechargestructures.

Hydrological StudiesFor determining the source water availability

for artificial recharge, hydrological investigationsare required to be carried out in the Watershed/Sub-basin/basin where the artificial recharge schemesare envisaged. Hydrological studies are undertakento work out surplus monsoon run off which can beharnessed as source water for artificial recharge.

Soil Infiltration StudiesIn case of artificial recharge through water

spreading methods, soil and land use conditionswhich control the rate of infiltration and downwardpercolation of the water applied on the surface ofthe soil assume special importance. These twophenomena are closely related since infiltrationcannot continue unimpeded unless percolationremoves infiltrated water from the surface soil.

Hydro geological Studies.A detailed hydro geological study providing

information on regional hydro geological rock units,their ground water potential and general pattern ofground water flow and chemical quality of water indifferent aquifers are necessary so as to knowprecisely the promising hydro geological units forrecharge and correctly decide on the location andtype of structures to be constructed in field.

Geophysical StudiesThe main purpose of applying geophysical

methods for the selection of appropriate site forartificial recharge studies is mostly to help andassess the unknown sub-surface hydro geologicalconditions economically, adequately andunambiguously. Mostly it is employed to narrowdown the target zone, pinpoint the probable site forartificial recharge structure and its proper design.Concept :

Figure (1) Elements of RWH system

Figure (2) Components of Rooftop RWH system

‘In situ’ precipitation will be available almost atevery location but may or may not be adequate tocause artificial recharge but the runoff goingunutilised outside the watershed/ basin can bestored/ transmitted through simple rechargestructures at appropriate locations. Various kindsof recharge structures are possible which can ensurethat rain water percolates into the ground instead ofdraining away from the surface. While somestructures promote the percolation of water throughsoil strata at shallow depth (e.g. recharge trenches,permeable pavements) others conduct water togreater depths from where it joins the ground water.(e.g. recharge wells). At many places, existingfeatures like wells, pits, and tanks can be modifiedand be used as recharge structures, eliminating theneed to construct any structures afresh.

A few commonly used artificial rechargingmethods are explained here. Innumerableinnovations and combinations of these methods arepossible.

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a. Direct surface techniquesFloodingBasins or percolation tanksStream augmentationDitch and furrow system

.b. Direct sub surface techniques

Dug well/Bore well rechargeRecharge pits /Recharge wellPercolation pit (Soak away)Recharge trenchesModified injection wellAquifer storage and recovery

c. Indirect TechniquesInduced recharge from surface water source

.d. Recharging Techniques to arrest sea waterintrusion

I DIRECT METHODS

A. SURFACE SPREADING METHODS1. Flooding

This method is suitable for relatively flattopography. The water is spread as a thin sheet. Itrequires a system of distribution channel for thesupply of water for flooding. Higher rate of verticalinfiltration is obtained on areas with undisturbedvegetation and sandy soil covering.

2. Basin & Percolation Tanks

Figure (3) Generalized cross-section of artificialrecharge of groundwater using a surface

spreading technique.

This is the most common method for artificialrecharge. In this method, water is impounded inseries of basins or percolation tank. The size of basinmay depend upon the topography of area, a flatterarea will have large basin. The most effective depthof water in basin is 1.25 m because lesser or greaterdepths resulted in reduced rate of infiltration. Thismethod is applicable in alluvial area as well as hardrock formation. The efficiency and feasibility of thismethod is more in hard rock formation where therocks are highly fractured and weathered.

3. Stream Augmentation Seepage from natural streams or rivers isone of the most important sources of recharge ofthe ground water reservoir. When total water supplyavailable in a stream / river exceeds the rate ofinfiltration, the excess is lost as run off. This runoff can be arrested through check bunds or wideningthe steam beds thus larger area is available to spreadthe river water increasing the infiltration. The siteselected for check dam should have sufficientthickness of permeable bed or weathered formationto facilitate recharge of stored water within shortspan of time. The water stored in these structures ismostly confined to stream course and height isnormally less than 2 m. To harness maximum runoff, a series of such check dam may be constructed.

4. Ditch & Furrow system In areas with irregular topography ditches orfurrow provide maximum water contact area forrecharge. This technique consists of a system ofshallow flat bottomed and closely spaced ditches /furrow which are used to carry water from sourcelike stream /canals and provide more percolationopportunity. This technique required less soilpreparation and is less sensitive to silting. Generallythree pattern of Ditch & furrow system is adopted(i) lateral (ii) dendritic & (iii) contour. In area oflow-transmissibility the density of ditch & furrowwill be high.

B. SUB-SURFACE METHODS

(1) Artificial recharging of aquifers throughbore well/dug well

Figure (4) shows typical systems ofrecharging wells directly from rooftop runoff.

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Rainwater collected on the rooftop of the buildingbeing diverted by drainpipes to a settlement orfiltration tank, from which it flows into a rechargewell (bore well or dug well). If a bore well is usedfor recharging, then the casing of the bore wellshould be preferably be slotted or perforated pipe,so that more surface area will be available for thewater to percolate

Figure (4) Artificial recharging of aquifers throughbore well/dug well

Developing a bore well would increase itsrecharging capacity. Developing is a process wherewater or air is forced in to the well under pressureto loosen the soil strata surrounding the bore to makeit more permeable.

If a dug well is used for recharging the welllining should have openings, (weep holes) at regularintervals to allow seepage of water through the sides.Dug well should be covered to prevent mosquitobreeding and entry of leaves and debris. The bottomof recharge-dug wells should be de-silted annuallyto maintain intake capacity. It is preferred that thedug well or bore well used for recharging shall beshallower than the water table. This ensures thatthe water recharged through the well has a sufficientthickness of soil medium through which it has topass before it joins the ground water. Any old well,which has become dysfunctional, can be used forrecharging, since the depth of such well is abovewater level.

Settlement tank :Settlement tanks are used to remove silt and

other floating impurities from rainwater. Asettlement tank is like an ordinary storage containerhaving provisions for inflow (bring water from thecatchment), out flow (carrying water to the rechargewell) and over flow. A settlement tank can have anunpaved bottom surface to allow standing water topercolate into the soil.

Apart from removing silt from the water, thede-silting tank acts like a buffer is the system. Incase of excess rainfall, the rate of recharge,especially of bore wells may not match the rate ofrainfall. In such situations, the de-silting chamberholds the excess amount of water till it is soaked upthe recharge structure.

Design Parameters :Providing the following elements in the system

can ensure the quality of water entering therecharging wells.1. Filter mesh at entrance point of roof top drains.2. Settlement Chamber.3. Filter bed.

Design parameters for settlement tank:For designing the optimum capacity of the tankfollowing aspects have to be considered.1. Size of the catchments2. Intensity of rainfall.3. Rate of recharge.

Since the de-silting tank also acts as a buffertank, it is designed such that, it can retain certainamount of rainfall, since the rate of recharge maynot be comparable with the rate of runoff. Thecapacity of the tank should be enough to retain therunoff occurring from conditions of peak rainfallintensity. In Mumbai, peak hourly rainfall is 90 mm.(Based on 25 year frequency). The rate of rechargein comparison to runoff is critical factor. However,since accurate recharge rates are not availablewithout detailed hydro geological studies, the rateshave been assumed. The capacity of recharge tankis designed to retain runoff from at least 15 minutesrainfall of peak intensity say 25 mm/hr.

Suppose the following data is available,Area of rooftop catchment (A) = 100 m2

Peak rainfall is 15 min (r) = 25 mm=0.025 m.

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Runoff coefficient, (C ) = 0.85Then capacity of the de-silting tank =A x r x C =100x 0.025 X 0.85 = 2.215 m3 (2125 lit).

(2) Recharge pits : (Recharge well)

Figure (5) Recharge pit Plan and section

A recharge pit is a pit 1.5 m to 3 m wide and 2m to 3 m deep. The excavated pit is lined with abrick/stone wall with (weep holes) at regularintervals. The top area of the pit can be coveredwith a perforated cover to allow entry of rain waterrunoff.

(3) Percolation pit (soak away) :

Figure (6) Percolation pit (photograph)

Figure (7) Percolation pit in section

A soak away is a bored hole of up to 30 cmdiameter in the ground to a depth of 3 to 10 m. Thesoak away can be drilled with a manual auger unlesshard rock is found at a shallow depth. The boreholecan be left unlined if a stable soil formation likeclay is present. In such a case, the soak away can befilled up with a filter media like brickbats or pebbles.In unstable formations like sand, the soak awayshould be lined with PVC or M.S. pipe to preventcollapse of the vertical sides. The pipe may beslotted or perforated to promote percolation throughsides.

(4) Recharge trenches :

Figure (8) Recharge trench in section

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Recharging through recharge trenches,recharge pits and soak away is simpler compared torecharge through wells. Fewer precautions have tobe taken to maintain the quality of the rainfall runoff.For these types of structures, there is no restrictionon the type of catchments from which water is to beharvested, (i.e.) both paved and unpaved catchmentscan be tapped.

A recharge trench is simply a continuoustrench excavated in the ground and refilled withporous media like pebbles, boulders or brickbats. Arecharge trench can be 0.5 m to 1m wide and1m to1.5m deep. The length of the recharge trench isdecided as per the amount of runoff expected. Therecharge trench should be periodically cleaned offthe accumulated debris to maintain the intakecapacity.

In terms of recharge rates, recharge trenchesare relatively less effective since the soil strata atdepth of about 1.5 m is less permeable. To enhancethe recharge rate, percolation pits can be providedat the bottom of the trench.

Design of a recharge trench :The methodology of design of a recharge

trench is similar to that for designing a settlementtank. The difference is that water holding capacityof recharge trench is less than the gross volumebecause it is filled with porous materials. A factorof loose density (voids ratio) of the media has to beapplied to the equation. Using the same method asused for design of settlement tank: Area of rooftop catchment (A) =100 m2

Peak rainfall is 15 min. (r) = 25 mm (0.025 m)Runoff coefficient (C) = 0.85Voids ratio D = 0.5 (assumed)Required capacity of recharge tank= (A x r x C)/D= (100 x 0.025 x 0.85) / 0.5= 4.25 m3 (4250 liters)

The voids ratio of the filter material varieswith the kind of material used, but for the commonlyused materials like brickbats, pebbles and gravel, avoid ratio of 0.5 may be assumed.

In designing the recharge trench, the lengthof the trench is an important factor. Once therequired capacity is calculated as illustrated above,length can be calculated by considering a fixed depthand width.

(5) Modified injection wellInjection techniques use wells to accomplish

artificial recharge. Injection wells usually placewater directly into a deep, confined aquifer wheresurface spreading would usually not work. Injectionwells also require maintenance to remove particles,microbial growth, and chemical precipitates (solidsubstances).Hence, modified injection wells arepreferred.

Figure (9) Modified injection well

In this method water is not pumped into theaquifer but allowed to percolate through a filter bed,which comprises sand and gravel. A modifiedinjection well is generally a borehole, 500 mmdiameter, which is drilled to the desired depthdepending upon the geological conditions,preferably 2 to 3 m below the water table in thearea. Inside this hole a slotted casing pipe of 200mm diameter is inserted. The annular space between

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the borehole and the pipe is filled with gravel anddeveloped with a compressor till it gives clear water.To stop the suspended solids from entering therecharge tube well, a filter mechanism is providedat top.

(6) Aquifer Storage and Recovery

Figure (10) Generalized cross-section of aquiferStorage and Recovery

Aquifer storage and recovery is a special typeof artificial recharge of groundwater that uses dual-purpose wells for both injecting water into theaquifer and recovering (withdrawing) it later.Although the intent of artificial recharge generallyis to increase groundwater storage for later use,incidental activities such as excess irrigation, stormwater disposal, canal leakage, and leaking waterpipes may also result in artificial recharge. Artificialrecharge and aquifer storage and recovery arevaluable water management tools that effectivelyhelp to offset increased demands for water.

II INDIRECT METHODSC. INDUCED RECHARGE

It is an indirect method of artificial rechargeinvolving pumping from aquifer hydraulicallyconnected with surface water such as perennialstreams, unlined canal or lakes. The heavy pumpinglowers the ground water level and cone ofdepression is created. Lowering of water levelsinduces the surface water to replenish the groundwater. This method is effective where stream bed isconnected to aquifer by sandy formation.

The greatest advantage of this method is thatunder favourable hydro geological situations thequality of surface water generally improves due to

its path through the aquifer material before it isdischarged from the pumping well.

D. RECHARGING TECHNIQUES TOARREST SEA WATER INTRUSION

The situation of over-extraction of groundwater in coastal aquifers cause problem of seawaterintrusion. The method that is used to control seawater intrusion is to use recharge well barriersthrough a line of injection tube wells driven parallelto the coast. This mechanism establishes a pressureridge which pushes the saline front seawards.

SPECIAL PRECAUTIONSWhether the harvested water is used for direct

usage or for recharging ground water, it is of utmostimportance to ensure that the rainwater collected isfree of any pollutants that might be added torainwater from the atmosphere or the catchment.While polluted water directly used for consumptionwould have an immediate impact on health, pollutedwater recharged into the ground would cause longterm problems of aquifer pollution. Damage doneto aquifers by recharging polluted water isirreversible.

Most of the precautions to ensure rainwaterquality have been summarized below.(1) At the catchment level8 Keeping the catchment clean8 Using gratings to trap debris at the catchmentitself8 Paving the catchment with ceramic tiles stonetile or other such non erosive materials

(2) At the conduit level.8 Provision for first flush to drain off from initialspell of rain

(3) Before recharging.8 Allowing for sedimentation of water8 Filtering the water

In establishments like industries it is verynecessary to ensure that the catchments surfaces arefree of chemical wastes, fuels, lubricants etc.Whilephysical and biological impurities in water can beeasily removed by de-sedimentation and filtration,it is very difficult to remove chemical impurities.

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SCALE OF WATER HARVESTING:Most methods described here are applicable at

a singular building or establishment level. However,the same principles can be applied for implementingwater harvesting at a larger scale, say, a residentialcolony or an institutional cluster. To an extent, thenature of structures and design parameters remainthe same; the physical scale and number ofstructures may increase corresponding to the sizeof catchment.

To control the total amount of runoff receivedby a large-scale system, the catchment can besubdivided into smaller parts. A locality-level waterharvesting system illustrated in figure shows howthe runoff from individual houses can be dealt withat the building-level itself, while remaining runofffrom the storm water drain (which drains water fromroads and open areas) can be harvested byconstructing recharge structures in common areas

Figure (11) Tapping storm water drains in a community level system

References:1. ‘A Water Harvesting Manual’ Published by Centre for Science andEnvironment2. ‘Guide on Artificial Recharge to Ground Water’ Published by Central GroundWater Board, Ministry of Water Resources3. web site www.rainwaterharvesting.org4. www.waterencyclopedia.com5. http://www.aboutrainwaterharvesting.com/rwh_methods.htm

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1. INTRODUCTIONThe rapid development in science and

technology in the world has brought the countriescloser to each other and the world has become aglobal village. ‘Vasudeiva Kutumbakam’ (The worldthe one family) is the need of the day. The integratedworld is the new concept which Acharya VinobajiBhave had given in his slogan of ‘Jay Jagat’ longback in the same context.

However as we see our country progressing inthe global market there is increase in the suicidesof Indian farmers every year. Today, it is theresponsibility of engineers in all the disciplines tocome together to provide them with possiblealternatives to cope up with the problems ofenvironmental imbalances and scarcity of properknowledge to adjust with the weather uncertainties.

On the other side, there are urban cities whichare over-flooded with the population and finding thedifficulties like inadequate supply of municipal water.Even though Bombay Municipal Corporation is indenial of a water crisis, since October 2002 it hasmade it mandatory for all new constructions covering

an area of more than 1,000 square metres to installa rainwater harvesting system that will tap theterrace water and make it flow to a bore well.

The BMC will henceforth supply such buildingsonly 90 liters/person/day for drinking, cooking, whereas they are expected to derive another 45 liters/person/day from rain water for flushing of toiletsand other not potable uses.While many builders haveonly recently and grudgingly started implementingBMC’ s directive, it will come as a surprise to manythat the costs of doing it are not that high.

2. THE PRINCIPLE OF RAINWATERHARVESTINGRainwater falling on the ground is absorbed

by the earth and it constitutes the groundwater. Thiswater is stored amidst the loose soil and hard rocksbeneath the earth’s surface just as sponge storeswater. Just as the water can be sucked out of asponge, so can groundwater be sucked out frombeneath the earth through bore wells. All this canhappen only if the rainwater is allowed to touch theloose earth. Extreme urbanisation in a city like

9. The Scope of Rainwater Harvesting in Urban Areas

*Sandip. H. Deshmukh **Prof. R. B. Magar

*Asst.Professor **Sr.LecturerFr. Agnel Technical Education Complex, Sector 9A, Vashi, Navi Mumbai 400703.

E-mail: [email protected], [email protected]

Abstract :A project is being undertaken for the feasibilty study of RainWater Harvesting for

the buildings in the premises of Fr.Agnel Technical Education Complex, Vashi. Theresearch is being carried out as a part of one of the objectives of Agnel SevaAshram, ‘Save Electricity & WaterAbhiyan’ (SEWA ). In a city like Mumbai, wherethe ground surface is heavily concretised, the main way to harvest rainwater is totap the water falling on the terraces of buildings. Thus, in residential or commercialbuildings, the pipes on terraces should be connected not to the BMC drains but toa recharge well or recharge pit. This process is termed ‘recharging’ the groundwater.The same bore well or tube well then can be used for pumping out the groundwater.Key words : Aquifer, Recharging, Catchments Area, Average annual rainfall.


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Mumbai has meant that at least three-fourths of thecity’s surface area has been developed, that is,covered in hard concrete by way of buildings androads.

The BMC’s extensive drainage system in theform of big nullahs and small arterial gutters isdesigned to ensure that rainwater does notaccumulate on the roads and buildings. It is anothermatter that nullahs and gutters get choked withgarbage and silt and many areas of Mumbai stillexperience flooding. But even this flooded watercannot seep in through the hard concrete. Which isprimarily why one needs to devise techniques thatcan make the rainwater seep into the earth. It is alsonecessary to ensure that only reasonably purerainwater goes into the ground, or else there is agrave risk of contamination of groundwater. Thedifferent techniques to make rainwater seep into theground, which otherwise would not happennaturally, is known as ‘rainwater harvesting’.

In a city like Mumbai, where the groundsurface is heavily concretised, the main way toharvest rainwater is to tap the rainwater falling onthe terraces of buildings. The idea is to prevent thiswater from running off in BMC’s drains and divertit to bore wells or storage tanks. Thus, in residentialor commercial buildings, the pipes on terracesshould be connected not to the BMC drains but to abore well. This process is also termed as ‘recharging’the groundwater. The same bore well is then usedfor pumping out the groundwater for use.

3. THE PROJECTS DONE ON RWH INMUMBAILet us have a short survey on the projects on

RWH done in the past in Mumbai & near by area.

3.1 RWH for Indian Woman ScientistsAssociation The site of the construction is located atPlot.No.20, Sector 10A of Vashi, Navi Mumbai. Inthis site both the methods of rainwater harvestingi.e. storage and recharge is proposed. The site fallsin a deccan trap terrain with top layer covered withclay.

3.1.1 Recharging underground aquifersThe roof water from the top through the rain

water pipes can be collected by series of chamberswith interconnected pipes and diverted to therecharge well. The evaluation of rainwaterharvesting potential is done by the method shownthe Fig.1.

The collection chambers are designed to be of0.5 m x 0.5m x 0.5m in size and the interconnectingpipes are of 6 inches in diameter.

The recharge well is of 2m x 1.5m x2m in size,and the recharge bore of 20m depth. This rechargewell can be filled with filtering materials consistingof layer of pebbles and sand each of 0.3m inthickness. In the recharge well a recharge bore wellof 6 inch diameter of 50m depth should be drilledusing air compressor.

A slotted casing pipe of 1m length should beprovided inside the recharged well. This slotted pipewill be wrapped with coir rope to prevent the entryof fine silt into the recharge bore well. The cost forrecharge well including collection chambers andinterconnecting pipes is Rs.30, 000.

This will consolidate our methodology & validate theprocedure. The simple formula to find the waterharvesting potential is given below in Fig.1.

Fig.1 : Evaluating Roof Top Rainwater Harvesting Potential

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3.1.2 Trench cum percolation pit : The surfacerunoff from the drive way, lawn and the part of theroof water normally flows to the road would beharvested by constructing a collection trenchmeasuring 2.5m length,0.5m width and 0.75 mdepth. This will be covered with a metal grill foreasy vehicular movement. The runoff collected will

be used for recharge purpose by constructing twopercolation chambers of 0.5m x 0.5x 0.5m in sizewith a recharge bore of 10m depth of 6 inchdiameter. The collection chamber can be providedwith pebbles for filtering purpose. Two numbers oftrench cum percolation pits will be constructed intwo gates and the total cost will be Rs 40,000.

Fig. 2 : Design & Estimate of Recharge Well

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Fig. 3 : Trench cum Percolation Pit

3.1.3 Storage tank system: The rainwater can bestored in a sub surface concrete tank below groundlevel and will be used for flushing purpose. Thissump can be either in addition to the existing tanksor if the drinking water is stored in separate tank,the rainwater can be directly routed to existingstorage tanks through filtration chamber.As per ourobservation the association has routed the completeroof water to the existing storage tank of capacity50,000 litres through a filtration chamber of size1m x 1m x 1m.The first flush device is a diversionvalve of 3 inch size. The initial rooftop rainwaterwith silt is flushed out to the sew age drain.

Then the filtered water from the filtering tankis connected to the storage tank. The cost ofconstructing the storage tank along with first flush,filtering tank & interconnecting pipes is 72,000/-

3.2 RWH proposal for Anoopam MissionCentre, Kharghar : Another case study was observed to be carriedout for Anoopam Mission Centre, Kharghar, andNavi Mumbai.

The options for RWH proposed a) Storage ofRainwater b) Recharging Underground AquifersThe Average Annual Rainfall in the region is 2250mm with Runoff coefficient 0.85 (as per CSE).

Catchment’s Area & Potential RainwaterQuantity :

Consider the Terrace (Roof top) Area as theminimum catchment’s area available: 656 Sq.m.Quantity of Water available =656sq.m x 2.250x0.85=1254.6m3 =12, 54, 600 Litres/4moths

Assuming 50 days of the rainy days per yearthe Harvestable Water per day =25,092L/day

Fig. 4 : Design of Storage Tank Design

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Water Requirements /day (Min): 50 Residents @ 135 L/ h /day =6,750L

60 Day staff or Personnel @ 45L/h/day =2,700L1000 Visitors @15L/h/day =15,000LTotal Flushing Requirements = 11,100L /day

Garden Requirements = 680 Sqm @ 4L/sq.m= 2,720 L /dayTotal Water Requirements =27,170 L /day

The harvested rainwater can be used forflushing and gardening purposes. The rain waterfrom the terrace is to be routed to an undergroundRainwater Storage Tank though a silt trap & 2filtering tanks each of 1mx 1mx1m size with afacility for bypass or overflow into Cidco StormWater Drain or Nallah. The terrace and filter medianeeds to be cleaned before letting water into tankand mesh filter should be provides at the rainwaterpipe inlet. No fertilizers or pesticides should beallowed to enter the system. Thus with the abovedata a suitable size of the tank can be arrived.

3.3 RWH in Urban Housing Societies3.3.1 Potential and estimate of installingrainwater harvesting in a 12-year old building inKandivli :

In the Coronet Co-op. Housing Society,Lokhandwala Township, Kandivli there are twowings of seven floors each and four flats on eachfloor. That means the total flats are 56 with the areaof terrace equal to 360 sq. m.

Assuming the average yearly rainfall inBombay of 2 metre high per sq. m.

The harvestable rainwater volume: 360 sq.m x2m x 0.85 = 612 (cu. m.) = 612,000 litres

One-time estimated cost of installing arainwater harvesting system is evaluated as shownbelow:

For 50-250ft deep bore well : Rs 45,000 to Rs60,000

Settlement tank and filtration tank: Rs 15,000to 30,000 adjacent to bore well

Piping work: Rs 15,000 to Rs 20,000==============================================

Total cost : Rs 75,000 to Rs 1, 10,000(Average cost per flat = Rs 1350/- to 1965/-)

==============================================3.2.2 RWH for Ekta Woods : In the month ofFebruary 2006 it was observed that a new group of

buildings, Ekta Woods of Ekta Shelters Builder atBorivli (East), having three wings of eight floorseach and four flats on each floor, the rainwaterharvesting system was in the final stage ofconstruction. A casual enquiry with the site-supervisor revealed that its total cost was about Rs300,000. When you average it out across thecollective 96 flats in the three wings it worked outto just Rs 3,100 per flat which is just 0.17 per centof the average cost of a flat of Rs. 18,00,000.

4. THE PROJECT ON RWH ATFr. A. T. E. COMPLEX :

A project is being undertaken for the feasibilitystudy of Rainwater Harvesting for the buildings inthe premises of Fr. Agnel Technical EducationComplex, Vashi. The research is being carried outas a part of the one of the objectives of Agnel SevaAshram (ASA) as to ‘Save Electricity & WaterAbhiyan’(SEWA).

4.1 Factors Influencing RWH potential: There are various factors which are influencingRWH potential. Rainwater harvesting is catchingrainwater, when and where it falls for the use. Itcan be done in two ways, either by diverting it intotanks, ponds etc or as ground water by injecting intothe soil aquifers.

The choice of the system depends on• Geography of area, topographical features ofthe site etc.• Ecological and climate conditions• Rainfall available at the site• The rainfall Pattern• Site characteristics like type of catchments,runoff coefficient of site

4.2 Benefits Projects on RWH:1. It is an attempt to make a standby arrangementor emergency supply services for the water needsof the complex.2. Rain water harvesting replenishes the groundwater table and enables the dug wells and bore wellsto yield in a sustained manner.3. If ground water is brackish, harvesting willreduce the salinity of water. Flooding of low lyingareas and roads can be avoided to a large extent,since rain water that is not harvested both within

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the house as well as out side is responsible forflooding.4. Rain water harvesting can be used for irrigationpurpose.5. It promotes conjunctive use of river, rainground, and sea and sewage water.6. It prevents unsustainable exploitation of theaquifer.7. It ensures efficiency, economy and equity in thewater use through co-operative management ofwater sheds and command area.

4.3 The various plans of RWH :• Plan A : The first option is to utilize the threeexisting water tanks of fire fighting system ofcapacity 1,52,400 liters (50800*3) to fill therainwater collected from the roof top. We can routethe rainwater pipes of the BalBhavan & Boy’s hostelBuilding to these tanks through properinterconnected pipes, Devas filters and filtrationchambers.

These two buildings have got rain waterharvesting potential per year of 16,25,630 liters. Theyearly flushing requirement for the two building peryear is 71,35,750 liters (considering 85litresconsumption per day per capita excluding drinkingwater requirement).

There is one more tank of capacity 1,020,50liters which can be used for drinking purpose. Thereis a provision to divert the BMC water supply tothis tank with a flow control valve to fill the otherthree tanks if these tanks remain empty. One of the water pumps would be pumpingthe water from these three interconnected tankssupplying water to the buildings of Boy’s hostel &BalBhavan for flushing.

Fig. 5 : Routing rainwater to the storage tanks

Plan B : To dig a trench of 3m deep and 1m widealong the inside portion of the compound wall andfill it with HDPE (High Density Poly Ethylene)Film and clay along the length of the wall of thecampus as shown in the fig 6. This will not allowthe saline sea water to drip into the soil ofFr.A.T.E.C.campus. Then using the bore wells of15m to 18m deep we will pump out the existingsaline water from the soil creating the voids whichcan be recharged with the rainwater. Using therecharge well technique we will fill the undergroundaquifers with the rainwater collected from the rooftops as shown in Fig 7. Then we can take twoadditional bore wells to retrieve this stored waterduring non monsoon season. The care should betaken that we pump less quantity of water than whatwe will recharge. We are also trying to constructopen well instead of bore well if it is feasible.

Fig.6 Compound Wall of HDPE Film

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• Plan C : The third plan is most assured way ofgetting the rain water collected from the roof tops.This includes collecting the water from the rooftopsinto underground tanks or open wells designedaccording to rooftop area and the average annualrain fall.

This plan has limitations of high initialinvestment cost of constructing tanks of Rs.1000/-per m3 and regular maintenance of the filters.However this is the most ensured way of gettingthe rainwater during the no monsoon season. Withproper filtration system incorporated we can evenuse rainwater stored in these tanks for drinkingpurpose.

Fig.7 Recharging bore well withWall of HDPE Film

• Plan D : In this plan we are planning to mountloft tanks wherever necessary in staff quarters. Therainwater pipes can be routed to these tanks fittedin the houses. These tanks can be interconnected insuch a way that, once the tank on the upper floor isfull, water starts filling the tank on the adjacentlower floor. These tanks can be used only to storewater for flushing purpose.

5. PILOT STUDY FOR DIFERENT PLANS

5.1 PLAN A:Total Catchments area of = 530 + 320 = 850 m2

Boy’s Hostel and BalBhavan

Average annual rainfall = 2.25 min Navi-MumbaiTotal quantity of Harvestable Water = 850 X 2.25= 1912.5m3

Considering 15% losses = 1912.5 X 0.85 = 1625.625 m3

(For four months)Total quantity of water available = 16, 25,625 L(By considering 50 Rainy days)Quantity of harvestable water = 32,512.5 L /Day.Assuming the requirement of 85L /capita/dayThe total requirement of water for = 230X85x365= 19,550L/day = 19.55 m3 /Day =136.85m3/Weekboth the buildings.

Fig. 8 : Rainwater Harvestingfor Bal Bhavan Building

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As mentioned earlier, we have decided toroute the rainwater pipes of the BalBhavan & Boy’shostel buildings to the existing three tanks of firefighting system of capacity 50,800L each throughproper interconnected pipes, filters and filtrationchambers. The total size of water that can be storedwill be 1,52,400L i.e.152.4 m3.This will be quitesufficient for weekly storage of rainwater 136.85m3

during rainy season. Also after the monsoon thiswater will be sufficient for 152.4/19.55 = 8 daysduring summer season.

Then the total volume of 450m3 rain water can beharvested by the method of under ground storagewater tank.

This will be sufficient for 450/37.5=12 daysof non monsoon season saving the equivalent costof Rs.4,950/- per Year.

Fig. 9 Rainwater Harvestingfor Boys Hostel Building

5.2 PLAN C:Total catchments area = 2500 sq. m.Average annual rainfall = 2.25 m in Navi-MumbaiTotal quantity of Harvestable = 2500 x 2.25

= 5,625 m3

WaterConsidering 15% losses = 5625 x 0.85

= 4,781.25 m3

Total quantity of water available = 47, 81,250 L(For four months)

(By considering 50 Rainy days)

Quantity of Harvestable water = 95,625 L / Day

available per dayAssuming the requirement of 15L /capita/dayThe total requirement of water = 2500 x 15 =37,500L/day = 37.5m3 /Day

If we design and construct two tanks of size15m length X 5m Width X 3m depth having thetotal Area = 225m3

Fig.10 Rainwater Harvesting of Fr. Agnel Degree&Diploma Buildings

5.3 PLAN B :We are trying to implement this plan by first

doing hydro geological investigation and estimatingthe rough estimate of construction of gravel packring well cum bore well. This is necessary to becarried out in order to identify points or locationsfor ground water development. As per the quotation

Fig.11 A open tank constructed with HDPE film

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from one of the consultants the assessment cost willbe Rs 7,500/-

After this assessment we will be able toconclude whether we can take open well or not. Alsothe estimate for one gravel pack ring well cum borewell given including all taxes is 1,53,210/-. Forprotection against the saline water to enter insidethe soil of the complex, HDPE film of gauge 500micron can be used as imperious film in the trenchthat we are going to excavate .The cost of the filmis around Rs.50 per m2. We have to calculate thefilm area required and the quantity of excavation of

the trench. The rate of excavation depends on thestrata below the ground.

5.4 OBSERVATION TABLESAfter carrying out the pilot study we have made

a observation Table 1, comparing the waterharvesting potential of each building with the annualwater requirement .This also facilitate cost benefitanalysis of the project. Also Table 2 shows the roughestimate of the particulars of Plan A which very soonwe have decided to implement.

NO. PARTICULAR ITEM UNIT RATE / UNIT TOTAL QNTY. TOTAL COSTI PVC PIPES 1 DIA.100mm m 155 28.22 4374.12 DIA.120mm m 165 56.6 93393 DIA.140mm m 175 29.92 52364 DIA.150mm m 180 15.9 28625 DIA.160mm m 185 18.5 34225II DEVAS FILTER - 600 7 4200III ELBOWS 45° ANGLE - 100 7 700IV 1 EXACUVATION m3 150 17.89 2683.52 P.C.C. m3 15000 1.19 17853 BRICK WORK m3 1400 7.45 10430

TOTAL RATE : 55,469.10/-

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Fig.12 Fr. Agnel Technical Education Complex, Vashi

6. FURTHER STUDIES IN PROGRESS We have decided to first implement Plan A which involves designing the interconnecting pipes withDEVAS filters. The rain pipes will be connected to main pipeline through these filters that are costingapproximately Rs. 600/- each. The following figure shows the DEVAS filters which can be manufacturedeasily from PVC pipes and sands of various sizes. The crucial factor is soil assessment and determination inwhat way we can recharge and retrieve the rainwater. This will be the area of our further research.

Fig.13 : Manufacturing of Devas Filters for Water Purification

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7. CONCLUSION and FUTURE SCOPEAs per our Vedic scriptures the Great Saint

Parashara says|| Annam Hi Dhanya Sanjatam, Dhanyanm KrishyaVina Na Ch ||Tasmad Sarvam Parityajya, Krushim YatnenKarayet ||1|||| Vrustimula Krushi Sarva, Vrushti Mulam ChJeevanam ||Tasmadadau Prayatnen,Vrushti dhnyanamSamacharet ||2||“Which means we get food from grains.Withoutdoing farming we can not get grains. Thereforeleaving every thing aside we should do harvesting.As the root of agriculture is in the rains, life isdependent on rains. Therefore we should verymeticulously study the rains”

Thus in the direction of his guidance we marchforward to get more and more knowledge about rainharvesting and water management. We should feelproud of harvesting rainwater in our own houses

and flats, complexes since it makes us more selfsufficient and less dependent on government for ourrequirements of fresh water. Let us make a sincereattempt to harvest rainwater falling on both rooftopas well as the open area all around our homes toprevent any further deterioration of ground watersource.

8. REFERENCES• Anil Agarwal, Available from: http://www.rainwaterharvesting.org Accessed: 2006-07-23• Sunita Narain & Rahul Ranade (2003). A WaterHarvesting Manual, Centre For Science AndEnvironment, New Delhi• M. Jacob, (2005), ‘Technical Report for rainwaterharvesting’, Navi Mumbai• Gopal Chandorkar (2005). Parjanya Mapan vaPurva Anuman, Proceedings of Traditional Wisdomin Water Management, pp. 96-101, A NationalConference at Nasik, October 2005, The IndianCouncil for Water & Culture, Aurangabad

“WATER SCARCITY DIVIDE PEOPLE…..….. RAINWATER HARVESTING UNITES THEM”.

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INTRODUCTIONIt is estimated that 80% of all diseases and over

1/3rd of deaths are caused by consumption ofcontaminated water and on an average as much as1/10th of each person’s productive time is sacrificedto water related diseases. India supports 1/6th of theworld’s population on 1/50th of world’s land withmeager 1/25th of the world’s water resources. Dueto the indiscriminate discharge of untreated sewageand industrial effluents into natural water bodies, thequality of surface water as well as ground water isdeteriorating in India. Deteriorating water quality has

10. Measures for Water Conservation andImprovement in Water Quality

*R. S. Goel **V. B. Patel

*Former Vice-President, Indian Water Resources Society, Former Convenor of Programmes, Water ManagementForum, Convenor, Coordination Committee, Water Related National Professional Societies, Chief Engineer,Narmada Tapi Basin Organisation, Central Water commission, Sector 10 A, Gandhinagar (Gujrat) – 382043

E-mail - [email protected]**Vice-President, Indian Water Resources Society, Former Chairman, Central Water Commission, Former Chairman,Board of Governors, Water Management Forum, Co-chairman, Coordination Committee, Water Related NationalProfessional Societies, 128, Manekbaug Society, Ambawadi,Ahmedabad–38 00 52 E-mail - [email protected]

ABSTRACTSafe water supply and environmental sanitation are vital for protecting the

environment, improving health and alleviating poverty. According to the World Bankestimates, water pollution accounts for about 60% of the major annual environmentalcosts in India. Availability of water in India is under tremendous stress due to growingpopulation, rapid urbanization, increase in per-capita consumption, industrial growthand other demands for maintaining ecology. It is to be stressed that non-developmentof water storage projects is not a viable or available option; due to the large temporalvariations in river flows in Indian monsoonic climate. Integrated water managementis most vital for poverty reduction, environmental sustenance and sustainableeconomic development in India because water has the potential for both diseasecausation and prevention. This article highlights the challenges in supplying thequalitative water for the bulging requirements of water for various uses in our highlypopulated country and suggests measures to overcome the serious crisis. The articlewould help the policy planners, municipal agencies and professional societies toproperly focus and channelise their energy for integrated water resources developmentand management.

Keywords- water quality, water management, wastewater, reuse, recycle,

become a serious problem. Safe water supply andenvironmental sanitation are vital for protecting theenvironment, improving health and alleviatingpoverty. Unless facilities for the treatment ofdomestic sewage and industrial effluents are manifoldincreased, the increasing pollution load due tourbanization will further deteriorate the quality ofwater bodies. Preserving the quality and theavailability of the freshwater resources is the mostpressing of the many environmental challenges onthe national horizon. It is imperative that conservation,recycle, reuse of precious water and proper


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treatment of waste are given serious attention forsustainability of built environment for our highlypopulated country.

CONCENTRATED WATER NEEDS DUE TORAPID URBANIZATION

During last 50 years the share of urbanpopulation in the country has increased from 14% to33%. During the last fifty years the population ofIndia has grown two and half times, but Urban Indiahas grown by nearly five times. India’s populationhas already crossed 1 billion mark and it has beenassessed that the urban population may reach 50%of the total population by the middle of this century,as against about 33% at present. Already there isacute shortage of drinking water supply in cities likeBangalore, Delhi, Mumbai, Hyderabad and Chennaiand water is being transmitted long distance to caterto the needs. Between years 2000 and 2050freshwater withdrawals by urban areas will risefrom an estimated minimum of about 15 BCM to aprojected maximum of about 60 BCM. Options likewatershed management, rainwater harvesting,groundwater exploitations, which create spatiallydistributed resources, are unable to meet theseconcentrated demands. Supply of safe drinking waterto such a large urban population besides meeting thecommercial, industrial, cattle and recreationalpurposes is proving a Herculean task and calls forcreating concentrated sources of water to meet theconcentrated demands.

WATER CONSERVATIONWater Conservation has three broad

connotations; maximum storage of rainwater,economical and optimal use including prevention ofwastage/ leakage and multiple use – Reuse andRecycling. In urban water supply almost 30 to 40%of the water is wasted through the distributionsystem. In Industrial sector also, there is a scope ofeconomy in use of water. Public awareness shouldbe generated through a massive campaign ofcommunication through all available media and bythe utility management itself setting an example forconservation. All urban dwellers should be madeaware of the source from which water is beingbrought to the city and from which additional waterwill have to be brought in the future. They shouldbe aware of the costs involved, not only in financial

terms, but also the cost that other communities haveto incur in terms of opportunity lost by not using thewater. The measure for water conservation shouldinclude metering of supplies as a matter of policyand increase in tariff rate on a sliding scale. Use oftreated effluents, in place of filtered water forhorticulture and large gardens, and fitting of waste-not taps on public stand-posts to avoid wastage ofwater should be encouraged.

WASTEWATER GENERATIONBetween years 2000 and 2050 freshwater

withdrawals by urban areas will rise from anestimated minimum of about 15 BCM to a projectedmaximum of about 60 BCM. About 80 percent willbe returned as polluted wastewater to nearby surfacewater bodies. This will result in massive pollution offresh surface water resources. A large part of thesewage in most of the municipalities is still flowinginto the aquatic environment without any treatment,thereby increasing the oxygen demand in shrinkingwater bodies and increasing the bacterial load ofwater, the main cause of water borne diseases.Discharge of untreated domestic waste water ispredominant source of pollution of aquatic resourcesin India. Urban centers contribute more than 25%of the sewage generation in the country. The smallertowns and rural areas do not contribute significantamounts of sewage due to low per capita watersupply. Waste water generated in these areasnormally percolates in the soil or evaporates. Owingto the indiscriminate discharge of untreated sewageand industrial effluents into natural water bodies, thequality of surface water as well as ground water isdeteriorating. A result of this is that the principaldrinking water supply sources of cities and townsare becoming polluted of which is increasingconsiderably the cost of water treatment.

Even in the mega cities namely Mumbai,Calcutta, Delhi and Chennai; wherein about two thirdof the total wastewater of 23 metro cities isgenerated, the waste management is highlyunsatisfactory despite the huge infrastructure andparaphernalia due to many socio-political andmanagerial problems. Of the wastewater generatedin Class I cities, 12 metropolitan cities accounted forabout 65 percent. Mumbai and Delhi generated morewastewater than that generated in all the Class IIcities together. About 80% of about 20% collected

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wastewater in these cities was receiving primary orprimary and secondary treatment. Further, out of thewastewater generated in Class II cities, only 5%was being collected and only 2% was receiving somekind of treatment. Almost all the wastewater wasbeing disposed in the rivers and agricultural lands,affecting surface and ground water; creating highlyalarming situation.

The major water polluting industries are leather,sugar, distilleries, paper and pulp, chemicals, iron andsteel, and metal plating. A large part of industrialwater pollution is caused by small-scale units. Theintegration of proper water supply, recycling andreuse of water, roof water harvesting and adequatesanitation facilities in all cities and bigger towns isabsolutely vital for revival and maintaining theintegrity and purity of rivers eco-system. In the 8th

five-year plan 24 highly polluted stretches in riversof 16 states were identified and Ganga Action PlanPhase I & II were launched which were later onintegrated into National River Conservation Plan.Focus of the River Action Plans has been on sewagewith very little success with regard to the other twoforms of water pollution viz., industrial pollution andagricultural run off.

SURFACE WATER POLLUTIONAbout 75% of domestic water supplies from

urban areas come back as return flow, deterioratedin quality due to organic, chemical and bacterialpollution. Even though, drains and rivers have beenfunctioning as waste disposal channels from timeimmemorial; but the pollution load in earlier timeswas within the self-purification capacity of thesestreams. Due to the bulk of discharge of effluentswith very heavy doses of impurities of the modernday world which are mostly untreated, the pollutionload is now manifold and beyond the self-purificationcapacity of the rivers. Analysis of water quality datafor 1997 reveals that Gujarat tops in chemicalpollution, followed by Maharashtra, Andhra Pradesh,Tamilnadu , Uttar Pradesh and Punjab. The worstaffected states in terms of presence of coliformbacteria in water, are Uttar Pradesh, Gujrat,Tamilnadu and Assam. In terms of BOD valuesKerala is at the bottom and Maharashtra at the top(most polluted).

Many of the modern water pollutants are non-biodegradable. Greater abstraction of water,

especially during lean season for various diverse useshas greatly diminished the dry flows in streams. Toreverse this situation, moderation of floods andincreasing the dry season flows is imperative. Theincreasing discharge of domestic and industrialwastes has also led to the contamination of groundwater, making it unfit for human consumption atmany places. In some regions, over-exploitation ofground water has led to salinity ingress and severedepletion of ground water accentuated by lowrecharge capabilities. For small scale sector, ascheme titled Common Effluent Treatment Plant(CETP) has not been uniformity successful asdifferent units within the same complex releasedifferent types of effluents which cannot be treatedthrough a single technology. More important, poolingof resources for this common cause has not foundfavour with small scale & cottage industry.

Waste Water Generation from Different typesof Industries and Possible Reuse

Industry Average Volume of PossibleWasteland per Unit Percentof Product Reuse

Thermal Power 155 kl./hr/MW 98PlantPulp & Paper 250 kl./tonne 50Iron and steel 150 kl./1000 lit/tonne 40Pharmaceutical 4.5 kl./tonne 40Distillery 15 lit/lit of alcohol 25Textile 250 lit/kg cloth 15Tannery 34 lit/kg of raw hides 12

The main challenge lies in devising instruments,which make it attractive for corporate sector toconserve and recycle water by adopting less waterintensive processes and encourage material recovery.The direct regulation of the “Command and controlType” has not worked due to weaknesses inenforcement coupled with low level of penalty.Under regulation of this kind, perceived benefit fromconservation must be more than the cost ofcompliance.

GROUND WATER POLLUTIONRegulation and conservation of ground water

present technical and administrative difficulties

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because precise delineation of aquifers is difficultand monitoring and control of extraction by largenumbers of individually owned wells is not feasible.Accordingly, depending upon the characteristics ofthe pollutants and application of water, the pollutantsmay migrate to the saturated zone along with rechargewater, thereby affecting ground water quality. Thereasons for ground water pollution mainly related tothe faulty agricultural practices, industrial pollution,municipal pollution, mine pollution and naturalpollutants present in the ground water itself. CentralGround Water Board (CGWB) is monitoring thequality of ground water at 16,000 hydrograph stationsin the country.

ECOLOGICAL IMBALANCES DUE TODETERGENTS

The health risk posed by phosphate richdetergents is not yet recognized in India despite aworldwide awareness and ban in several countriesin Europe and America. Detergents contain manyingredients which could be a threat to the environmentand human health. A common ingredient, sodiumtri-polyphosphate (STTP) softens the water thushelping to remove dirt from clothes and to keep thedirt off during the washing cycle. Phosphorus, partof STPP is an essential nutrient for the growth ofaquatic plants and as such adds to the culturaleutrophication, a process in which the excessnutrients result in algae bloom, kill fish and increasepathogenic organism, causing loss in aesthetic andrecreational values of water. Strict regulations bemade requiring that not more than 5% phosphorusin detergents.

WASTE WATER TREATMENTCare is necessary that treated wastewater

does not contain toxic matter beyond a threshold.Otherwise, it may enter the food chain, both aquaticand terrestrial. Besides, wastewater can damagefertility of soil and quality of ground water if itsconstituents are not kept within the prescribed limitFor the most economic disposal of wastewater fromvarious sources, recycling, re-use, renovation andregeneration (summed up by the term “4-RConcept”) must be practiced with utmost keenness.Recycling refers to repeating the same use; re-useis done by using effluent for other purposes;renovation refers to treatment to the (tertiary) level

so that it is fit for use like fresh water, andregeneration refers to replenishment of a watersource in a natural manner. Recycling and re-usehas been demonstrated to be cost-effective in a largenumber of cases, with periods of return ofinvestments ranging from a few months to less thanfive years. Thus it makes sense to practicerecycling/re-use for economic reasons, besides doingso to meet moral or legal liability associated withdisposal of wastewater.

EFFECTIVE RECYCLE AND REUSE OFWATER

In urban water supply, 30 to 40 % of themunicipal water is wasted through the distributionsystem. In Industrial sector too, there is a scope ofeconomy in use of water. As per estimates byBureau of Industrial Costs and Prices, 10 to 30%saving in water consumption in industries is possibleby recycling, modifications in processing, evaporationcontrol etc. Apart from ensuring leakage control,water conservation strategy in industries shouldinclude introduction of appropriate technology toensure efficient use of cooling and process waterand necessary pollution control mechanisms andmaximum recycling and reuse. Treatment ofwastewater in stabilization ponds is an effective andlow-cost method of pathogen removal, and is,therefore, suitable for schemes for wastewater reuse,particularly for irrigation of crops. Similarly,duckweed ponds are quite effective in treatingmunicipal wastewater and at the same time theharvested duckweed is a good fish and chicken feed.As such, there is a need to develop appropriate andcost effective technologies, for treatment and reuseof municipal wastewater, suitable to Urban LocalBodies for their adoption. Possible health risks toagricultural workers should, however, be assessedthoroughly and monitored regularly. Treatedwastewater should conform to pollution controlstandards for adopting reuse practice.

There are various options for recycling andreuse of grey water (bathroom and kitchen wash)and black water (sewage). However, the grey waterand black water from large residential complexeslike Cooperative Housing Societies, multistoriedbuildings and industrial effluents from large industriescan be recycled and reused for various purposesother than drinking. The grey water may be put into

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various types of treatment such as grease trap,anaerobic filter etc and the filtered water may be letinto wet land, polishing ponds etc. and can be reusedfor gardening and horticulture etc. The black watermay also be put into various types of treatment suchas screen, grit removal primary, secondary andtertiary treatment etc. and the treated waste watercan be let into wet land for irrigation or for groundwater recharge. The municipal wastewater andindustrial effluent may be treated up-to tertiary leveland used for various purposes other than drinkingby various industries and cities. For example, inChennai the Chennai Metro Board is providing 30mldtreated municipal wastewater to Ennore ThermalPower Plant for recycle and reuse for cooling &other purposes. Likewise in Mumbai, many of theindustrial houses are using the recycled industrialeffluent for purposes such as air-conditioning, coolingetc. In Pondicherry Ashram, the wastewater fromhousing complexes and community’s toilets arerecycled and reused for horticulture purposes andirrigation. State Governments may create UrbanDevelopment Fund for Urban Infrastructuredevelopment and the same can also be used forsetting up of pilot projects for waste reuse, recyclingand resource recovery.

INCENTIVES AND LEGAL ASPECTSSuitable fiscal concessions and subsidies may

be considered by the Central and State Governmentsto the industries, commercial establishments and anyother agencies which adopt/practice waste reuse,recycling and resource recovery. Similarly, in casethe Urban Local Bodies on their own would like totake the initiative and set up waste reuse, recyclingand resource recovery schemes in their respectiveareas, similar fiscal concessions and subsidies mayalso be made available to them. It may be mademandatory in phases that large industries andcommercial establishments must meet a sizeablepercentage of their non-potable water requirementsfrom the reclaimed water. Similarly, for irrigatingcrops, horticulture, watering public lawns/gardens,flushing of sewers, fire-fighting etc. reclaimed watershould only be used. Economic instruments mayprovide incentives to economic actors inducting themto behave in an environmentally responsible manner.Their merits include: effectiveness, efficiency,flexibility and incentives for eco-innovation. Under

the scope of the polluter pays principle we canconsider of such subsidies such as originating fromfunds created on the basis of pollution related charges(e.g. acidification funds).

RENTING OF WATERAbove economic instruments provide incentives

to economic actors inducing them to behave in anenvironmentally responsible manner. Their meritsinclude: effectiveness, efficiency, flexibility andincentives for eco-innovation. Under the scope ofthe polluter pays principle we can consider of suchsubsidies as originating from funds created on thebasis of pollution related charges (e.g. acidificationfunds). Another important thing about pricing ofwater may be costing it according to its end use.Farmers and low income industries may not becharged at the rate of charges fixed for high yieldingindustries.

MARKETING BOTTLED WATERConsiderably more satisfaction and benefit can

be obtained from the present water supply system,if managed efficiently. Costly systems areconstructed, but for want of proper operation andmaintenance, the benefits are not received by thepeople who have to incur considerable private costsand have to resort to alternate means orsupplementary sources. Fast catching up practiceof selling mineral water bottles at rates even morethan milk and more than 1000 times than the tapwater in India is paradoxical. While half of ourpopulation is unable to afford even the absoluteminimum needs to quench their thirst. Only watersupply utilities should be allowed to bottle and marketthe bottled water to generate much-needed fundsfor modernization and proper maintenance of existinginfrastructure.

PROTECTION OF NATURAL WATERRESOURCES

Responsibility should be fixed on various civicand industrial authorities to treat the wastewaterbefore disposing it in conveyance drains or naturalstreams. Water quality should be monitored regularlyat every out-fall drain. State wise river basinconservation plan should be formulated for differentbasins. The pathogenic, toxic and biological andphysico-chemical effects of various types of water

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pollution in different scenario and regions should bescientifically analysed, collated, understood andsuitable action plans should be framed.

QUESTIONABLE USE OF WATER AS ACARRIER OF WASTES

The traditional way of removing wastes fromindustries, and homes has been to dilute them in waterand then carry this wastewater over long distancesto extract most of the waste in the sludge, leavingpolluted water as effluent. Such traditional and highlyunscientific method of using water carriers of wastesneed to be closely examined. There are many betteralternatives to treat the waste at its origin, withoutusing so much water. Use of low flushing and drytoilets as well as use of ‘grey water’ drained fromshowers, kitchens and laundries to flush the toilets,should be targeted for adoption in at least in all newconstruction of commercial institutions and plannedcolonies in all class I and II cities.

MINIMUM FLOW REQUIREMENTQuality of river waters is deteriorating with

large number of municipal and industrial effluentsbeing discharged untreated into rivers. Return flowsfrom irrigated areas pollute river water with residualfertilizers, pesticides and herbicides. Necessity formaintaining minimum flow therefore, arise out of theneed to maintain water quality, river regime,maintenance of river eco-system or other publicnecessities.

SOCIO-ECONOMIC & ECOLOGICALASPECTS OF DROUGHTS

It is estimated that around 263 million peoplelive in drought prone area of about 108 m. ha., whichworks out to 1/3rd of the total Indian geographicalarea. Thus, more than 26% of total population ofthe country face the consequences of recurringdroughts, on a wide spectrum of social concerns.During the drought years there is a marked tendencyof intensive exploitation of ground water, resulting inabnormal lowering of ground water table thusaccentuating the distress. Grave adverse impactsare borne by flora, fauna and domestic cattle andthe very life itself fights against nature for its survival.Droughts accentuate problems in cities in the formof mushrooming of slums and pressure on the existingcivil amenities thereby adversely affecting urban life.

Large storage projects are essentially required fordiverting surplus water from flood prone areas todeficit areas. Indira Gandhi Nahar Project has beena boon for large tracts of Rajasthan in alleviatingdroughts.

SOCIO-ECONOMIC & ECOLOGICALASPECTS OF FLOODS

Over 40 million hectares of the area of thecountry experiences periodic floods. The averagearea affected by floods annually in India is about 7.5m. ha of which crop area affected is about 3.5 m.ha.Floods have claimed on an average 1,529 humanlives and 94,000 cattle ever year. Apart from loss oflife and domestic property, the devastating effectsof floods, sense of insecurity and fear in the mindsof people living in the flood plains is enormous. Theafter effects of floods like the agony of survivors,spread of epidemics, non availability of essentialcommodities and medicines and loss of their dwellingsmake floods most feared natural disaster being facedby human kind. Large-scale damages to forests,crops & precious plants and deaths of aquatic andwildlife, migratory and native birds in various NationalParks, Delta region, low altitude hilly areas andalluvial flood plains of Assam, Arunachal, Uttrakhand,U.P., Bihar, Orissa, West Bengal, have always beenthe matter of serious concern. River Valley Projectssuch as Bhakra, Ramganga, Hirakud, Pong etc. haveproved highly successful in moderating themagnitudes as well as frequencies of floods.

ACCELERATED WATER STORAGEDEVELOPMENT

Water demands forecasts show that Rajasthan,Maharashtra, Gujarat, Haryana, Karnataka andTamilnadu could face heavy water supply shortfalls.The water shortages would be far more serious inthe water short basins like the Cauvery, Pennar,Sabarmati, Mahi, and Krishna etc. To meet thebulging water requirements, it would be necessaryto ensure substantial augmentation of water supplies;requiring sufficient raising of water storagecapacities, thus necessitating completion of new largewater storage projects.

Supreme Court Majority Judgement forNarmada Projects has also highlighted that againstthe utilisable storage 690 cu. km. of surface waterresources out of 1869 cu. km.; so far storage capacity

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of all dams in India is only 174 cu. km., which isincidently less than the capacity of Kariba Dam inZambia/Zimbabwe with capacity of 180.6 cu. km.and only 12 cu. km. more than the Aswan High Damof Egypt. The impact on environment should be seenin relation to the project as a whole. Water of poorquality leads to ill health, whereas water in insufficientquantity claims large chunks of time spent inaugmenting the supply; otherwise, the significant timecould be spent on more remunerative tasks. We mustrealize the basic fact that the medium and smallwater projects as well as water harvesting schemescannot substitute the need of large water storagesbut can at best complement the larger projects. This,too, depends upon the hydrological, geological,topographical and regional limitations. Thecontroversy of the large versus small dams isirrelevant. Sustainable management of waterresources with due respect to ecological, economicand ethical sustainability blended with technicalfeasibility requires a holistic and integrated approachinvolving engineering, socio-economic andenvironmental aspects. Expansion of storagecapacity by completing on-going projects andconstruction of new projects is imperative to enhancewater availability.

ROLE OF COMMUNITIES ANDPROFESSIONAL SOCIETIES

It is essential that environmental aspects andthe process of planning and operation of waterresources projects be fairly understood by the expertsof different disciplines. Participation of people is amust in the management of water. People have tobe made an integral part of the water managementsystem. The community is to be made not only waterconscious, but also to be integrated to participate inthe planning and management of such projects andpollution prevention programmes. It is unfortunatethat a smear campaign has been launched duringlast two decades against hydropower and waterresources projects by exaggerating the likely orassumed adverse environmental impacts and bysuppressing their need and tremendous benefits.

Knowledge about the changes required incropping patterns and agronomic practices also mustbe communicated to farmers to sensitise them aboutthe constraints of water supply and motivate themto use it carefully and efficiently. Professional

societies can act as multi-disciplinary fora for nationaland regional debates, analysis and framing of actionplans on water related matters by utilizing theirinfrastructure, professional expertise, library,publication and documentation services. Thesesocieties can serve as rich sources in generatingtechnically sound options with well-defined limitations& assumptions in Indian peculiar situations for takinginformed decisions. The services of professionalSocieties like Indian Water Resources Society, TheInstitution of Engineers (India), Indian NationalScience Academy, Indian Water Works Association,Indian Association of Hydrologists, Indian Societyof Hydraulics, Water Management Forum,Association of Hydrologists of India & IndianBuildings Congress having vast network, good spreadand pool of expertise may be channelised in debating,dissemination and creating balanced scientific publicawareness.

WORKING GROUP ON WATER RELATEDECOLOGICAL MATTERS

Considering the seriousness and deterioratingstate of affairs concerning quality and quantity ofavailable water particularly for urban use, alarmingwater pollution levels and challenges in managingwater related ecological concerns, a Working Groupon Water Related Ecological Matters for X Five YearPlan was formed vide Planning Commission’s O.M.No. M-12018/1/2000-E&F dated 8th January, 2001under the Chairmanship of Secretary (WaterResources). The Group consisted of therepresentatives of the Planning Commission,Confederation of Indian Industries and the Ministriesof Environment and Forests, Agriculture &Cooperation, Urban Development & PovertyAlleviation, Industrial Development, RuralDevelopment, Department of Ocean Developmentas well as Chairman, Central Water Commission;Chairman, Central Ground Water Board; Chairman,Central Pollution Control Board and Member (RiverManagement), CWC. The first author of this articlewas inducted as Member Secretary for the Group.Working Group in its Report has suggested that thefollowing measures may yield significant benefitsfrom the overcoming crisis in the field of water relatedecological arena :

Strict measures to ensure proper treatment ofwaste water

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Strict enforcing of responsibility on users forwaste treatment before discharging into water bodies

Local bodies should be responsibile formaintaining CETPs

Economic Instruments as incentives andsubsidies to induce users accountability to curbincreasing water demands and to encouragerecycling and reuse of water

Suitable cess collected on marketing of waterbottles be exclusively reserved for modernization ofpublic water supply systems.

Water sensitive urban planningWide spread use of water saving fixturesStrategy based on agro-climatic regional

planningIntegrated planning and management of river

basinsDeclaration of water resources projects as

green projects in respect of environmental clearanceEquitable distribution of waterUse of appropriate technology in water supply

and sanitation sectorsScientific public awareness and curbing

environmental pseudoism.Encouraging professional societies for

feedback, documentation and proper disseminationResearch and development activities in the area

of water quality managementImpose restriction in water abstraction and

ensuring discharge of only treated sewage/ tradeeffluent on land, rivers and other water bodies witha view to mitigating crisis of water quality;

To maintain minimum discharge for sustenanceof aquatic life forms in riverine system;

Encourage rain-water harvesting, roof topharvesting for indigenous consumption

To utilize self assimilation capacities to minimizecost of effluent treatment;

Encourage ground water recharging with strictmonitoring of the water quality

To create public awareness on waterconservation and economical water usage.

CONCLUSIONIndia supports 1/6th of the world’s population

on 1/50th of world’s land with meager 1/25th of theworld’s water resources. Further, 80% of all diseasesand over 1/3rd of deaths are caused by consumptionof contaminated water and on an average as much

as 1/10th of each person’s productive time issacrificed to water related diseases. Deterioratingwater quality has become a serious problem. Wewould have to maintain a balance between the thrustareas of development (infrastructure and consumergoods), which are said to improve the quality of life,and the social aspects like bare necessities of life inthe areas of water, food, fiber, power, education,health, housing and nutrition. Preserving the qualityand the availability of the freshwater resources isthe most pressing of the many environmentalchallenges on the national horizon. Social tensions,political instability and street fights are already onthe horizon; due to stoppage and slowing down theconstruction of almost all major dams; ignoring thebulging demands of water and power for municipaluses in metro cities, by few environmental activistsand novelists; without professional analysis. It is tobe stressed that non-development of water storageprojects is not a viable or available option; due to thelarge temporal variations in river flows in Indianmonsoonic climate. Conservation, recycle, reuse ofprecious water and proper treatment of waste watermust be given serious attention for sustainability ofbuilt environment for our highly populated country.In such peculiar conditions, the initiative forinterlinking of rivers in India so as to meet the bulgingdemands of water for various uses even for waterstarved states is highly commendable and timely.

Note - The views in the article may not belong tothe Authors’ Organisations.

REFERENCES• Central Water Commission, 2000 ‘River ValleyProjects and Environment-Concerns and Management’,Publication No. 61/2000, New Delhi.• Goel R.S.(Editor), 1993, ‘Environmental Impacts ofWater Resources Development’, M/S Tata McGraw HillPublishing Company, New Delhi.• Goel R.S.(Editor), 2000, ‘Environment ImpactsAssessment of Water Resources Projects’, M/s Oxford& IBH Publishing Co. Pvt. Ltd., ISBN-81-204-1422-5, NewDelhi.• Goel R.S. (Editor), 2000, ‘EnvironmentalManagement in Hydropower and River Valley Projects’,ISBN-81-204-1423-3, M/S Oxford & IBH Publishing Ltd.,New Delhi.• Goel R. S. and Srivastava R.N.(Editors), 2000,

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‘Hydropower and River Valley Development’, M/s Oxford& IBH Publishing Co. Ltd., New Delhi.• Goel R.S., 2002, ‘Management of Water Supply andWastewater for Sustenance of Indian UrbanInfrastructure’, VIII Annual Convention and Seminar onUrban Infrastructure Development, Vigyan Bhavan, NewDelhi, 14-16, June 2002.• Goel R.S., 2002, ‘Integrated Water Management forSustenance of Indian Urban Environment’, InternationalConference on Water & Wastewater: Perspectives ofDeveloping Countries, 11-13th Dec, 2002, New Delhi.• Goel R.S. and Shete D.T., 2005, ‘Water QualityManagement in Urban Centres- an Overview in IndianContext’, XI Annual Convention and Seminar on WaterManagement in Urban Centres, Vigyan Bhavan, NewDelhi, 21-23, July 2005.• Goel R.S., 2000, ‘The Unquiet Narmada - TheAntagonism Against River Valley Projects Is Unjustified’,The Economic Times, New Delhi, 31st December 2000.• Goel R.S., 2001, ‘River Valley Projects, Dams areBeneficial’, The Times of India, , 11th May 2001, New Delhi

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• Indian Water Resources Society, 1999, ‘Theme Paperon Water Vision 2050’, New Delhi.• Indian Water Resources Society, 2002, ‘Theme Paperon Integrated Water Resources Development andManagement’, New Delhi.• Ministry of Water Resources, 1999, ‘Report of theNational Commission for Integrated Water ResourcesDevelopment’, New Delhi.• Ministry of Water Resources, 2001, ‘Report of theWorking Group on Water Related Ecological Matters forXth Five Year Plan’, New Delhi.• Prasad Kamta and Goel R.S.(Editors), 2000,‘Environmental Management in Hydro Electric Projects’,ISBN-81-7022-870-0, M/s Concept Publishing Company,New Delhi.• Supreme Court Judgement, 2000, ‘Narmada BahaoAndolan Vs. Union of India’, AIR, SCC, 2000.• Water Management Forum, 2002, ‘Theme Paper onInter-Basin Transfers of Water – Challenges andOpportunities’, New Delhi.

IntroductionIndia is facing a huge water crisis today. There

is an enormous unmet demand for water. Even asclean water sources are being viciously attacked bypollution and over exploitation, hardly any river orgroundwater aquifer near a city escapes the perilsof pollution today. While agricultural lands go thirsty,many thousands of villages find it difficult to get cleandrinking water. The dispute over tap waters heardin the history in olden days and in the villages inpresent times has been transferred to urban areastoo. The issue of water-crisis is more acute than thepetrol for which largely the human beings areresponsible.

There has been growing reliance on the use ofsurface and groundwater, while the earlier relianceon rain water and flood water has been declined,even though rain water and flood water are availablein much greater abundance than river water orgroundwater. It is reported that the money pumpedin for rural drinking water supply and methods usedwere unsustainable. Corruption, lack of people’sinterests in maintaining government schemes, landdegradation leading to heavy runoff, heavygroundwater exploitation leading to lowering ofgroundwater tables, neglect of traditional waterharvesting system and growing pollution are all added

11. Rainwater Harvesting and Water Management

Dr. S. G. Kirloskar

AbstractThe water crisis has taken considerable space in our lives. The problem of

water shortage has become a national and universal theme of discussion. Thewater crisis has become alarming to such an extent that unless every citizen startsacting towards saving and preserving the rainwater, the survival of present andfuture generations would be in jeopardy. Thanks to the environmentally awaremasses for sowing the seeds of rainwater harvesting in the society.

In this paper, some of the methods of rainwater harvesting, particularlyfeasible in urban areas, actually implemented elsewhere are discussed.

to the problem. The ecological balance has beencollapsed owing to irregular rains, environmentaldeterioration, and uncontrolled pollution.

The exclusive reliance on river and groundwateris already leading to a number of problems.

Heavy extraction of water from rivers : Therivers are so heavily exploited that there is no waterleft during the summer season. Agencies involved inwater resource development are not bothered toimplement the legislation for the minimum river flows.

Construction of large dams and neglect of smallwater harvesting structure :

Because of this, the numbers of displacedpopulations will steadily increase, while forests willsubmerge and availability of land for resettlementwill go down continuously.

Dependence on the state : There are financialand human problems with state sponsored watersupply. The state subsidises water. People squanderit. The state soon runs out of money for new projectsto meet the burgeoning demand and for maintainingprojects already built. The state becomes responsiblefor water supply. Demand will grow in futurebecause of population growth, increased urbanization,


Professor of Environmental Engineering and Principal of Rizvi College of Engg., Bandra (W), Mumbai 50

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industrialization. Increased water pollution has furtherreduced the availability of clean water which meansgreater stress on remaining sources of ground andsurface water.

To get the reliever, people started boring thetube wells only to lower the depth of water tablefrom 50 feet to 100-200 feet. The water crisis hasbecome alarming to such an extent that everyonehas to be educated to start saving and preservingthe rainwater. The concept of storing the rainwaterand elevating the level of water table, popularlyknown as ‘water harvesting’ has already taken itsroots.

In the villages, the rainwater harvesting is beingpracticed by building small bunds, by digging smalltrenches around the wells. However in urban areasspecific methods have to be applied for rainwaterharvesting. Some of the methods are listed(1) water from roof or terrace can be allowed topermeate near the bore or well or in the housepremises if bore or well is not available(2) water from roof or terrace can be taken(i) to well or bore through pipe or(ii) to an underground tank of sufficient capacity canbe built to receive the water through pipe.

The methods of water harvesting are describedbelow.(1) Permeating the water from the roofs intopremises of the house

Construction of underground structures of20,000 l capacity to harvest water from rooftops fordomestic consumption , manual withdrawal of water,to use runoff water as recharge in shallow wells.The capacity depends upon the no. of people in thehouses with average consumption of 7 l per capitaper day.

Many houses will not have bore wells or wells.One can utilize the open space available at any cornerof the plot for the permeation of water. A trench of9-10’ depth and 6-8’ length can be prepareddepending up on the availability of the space.As shown in fig. 1.1, the boulders of 2-3’ dia. areplaced up to 300 mm at the bottom of the trench.The sand layer of 1.5-1.75 m is placed over theboulders. The water from the roof and terrace shouldbe diverted into the trench. The bricks have to belaid on the boundary of the trench to avoid falling ofearth in the trench. Trench is covered with a grilled

lid to avoid contamination.

Fig. 1.1

Bleaching powder is applied to preventcontamination and maintain the quality of storedwater. Airtight covers on storage tank protect thewater from sunlight and contamination. Initialinvestment cost of the structure is little high.Operating cost consists of cleaning expenses oncein a year and periodic expenses of bleaching powderwhich would cost around only Rs. 1000/- per year.Considering the life span of the structure of 20 yearsand the relief it brings, this method is the mostreliable.

(2) A soak-pit can also be created at the outletpoint of the house premises

As shown in fig. 1.2, a soak-pit of 8’ depth and5’ length can be prepared containing brickbats,stones, boulders etc. The water starts filling up thetrench of the soak-pit. It is estimated that a smallsoak-pit gives 25000 liters of water in the monsoonseason.

Fig. 1.2

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(3) Diverting water from roof and terrace to boreor well through a pipe

The roof would be cleaned initially. Watercollected from the roof is taken to the bore throughpipe of 4.5" dia. As shown in Fig. 1.3, followingmaterial is required.(i) pipe of 6" dia., and 4’ length (ii) two reducers(iii) 4 mesh screen (iv) T pipe, 2 in number and Tcap (v) 4.5" dia. and 4.5’ length

The assembly of pipe filter can be fabricated.One end of this pipe is connected to the outlet endof the pipe from the roof. The other end of the pipefilter through a casing is directed towards the bore.The first rain water is allowed to drain. The systemcan be started operating from the second monsoon.The graded sand beds incorporated in the pipe actas filter. Thus there is three- stage filtration.

(4) The earthen bunds are placed at certainplaces in the farms and thus water is temporarilystored

Water is seeped through the soil. The earthenbund is constructed about 2-3 feet above the groundwith pitching done from inner side, as shown in Fig.1.4. The bund is constructed necessarily on the slopingground.

A trench of 2’x 8’ (depth) is prepared at a cornerwith pitching of stones on one side and a lining ofPVC sheet. The trench is filled up with the earth forrest of the year. In monsoon, the trench is filled upwith water before it starts spreading around. Wateris raised with this technique.

(5) Open air rainwater harvestingIn this a number of materials are used to capture

rainfall directly from the skies.(i) Polythene sheets (3m x 3m size) spread acrossin open air devoid of trees to collect direct rainfall.Water thus collected is cleaner than the roof runoff.The polythene sheet is mounted on 4 poles and ahole is made centrally for collection of water. Thistechnique is an ad-hoc one, which is installed priorto rain. Lot of water goes waste in heavy rains.Collection rate is 85-100 l/hr on an average rainfallday. This method is expensive and weak for windresistance.(ii) Galvanised sheet : A galvanized sheet of 2 m X1 m is spread in the open air. The sheet is tied fromthe two corners in the shape of a boat. The sheet ismounted on 4 or 6 poles in the open air. This methodis costly and faces rusting problem. The watercollected is limited sufficient for about 2 days for afamily of 7-8 members on average rainy day.(iii) Akshaydhara System:(a) First stage involves segregating the smallvolume of sanitary toilet waste and subjecting it toanaerobic bio-digestion and then discharging the liquideffluent into the city sewer system. This step involvesonly minor modification of the already existing civilwork as the drains toilet and non-toilet wastewatersare already separated in buildings as part of thenormal building construction practice.(b) The second stage involves construction ofpercolation wells in the housing societies for soil-aquifer treatment of the segregated non-sanitary

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Fig. 1.3

Fig. 1.4

wastewater and storm runoff water, to rejuvenatethe shallow ground water system. This would resultin reduction of wastewater to be discharged into thecity sewer system.(c) The third stage consists of providing separateplumbing and pumping / recycling system for non-potable water. This would gradually ease the load ofhigh quality public drinking water supply system.(d) In the fourth stage, the existing wastewatertreatment system can be augmented throughconstruction of infiltration basins and soil-aquifertreatment of the organic rich liquid waste collectedat the centralized sewage collection point.(e) In the last stage, the domestic sewerage systemcan be linked to city garbage collection system,wherein segregated recyclable waste is collected bythe dry waste collection network and the wetbiodegradable kitchen waste is disposed off in thecommunity bioreactor, the output of which beingliquid can be let out either into the city sewer systemor utilized locally for horticulture. With thecommissioning of bioreactors for kitchen waste, the

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sewer system will help reduce expenditure oncollection / disposal of wet biodegradable waste asrecyclable waste is more hygienic andenvironmentally sustainable. The biogas generatedcan be used for street lighting. This system is usefulin urban environment because of reduction of thecost of centralized sewage collection, reduction inhigh quality water supply thus ensuring resourcesustainability and involvement of the residents inmaintaining hygienic conditions in city. Fig. 1.5 shows“Akshaydhara” concept for total water management.

Facilitating urban water harvestingFollowing pints need to be undertaken:• All water bodies in urban areas should becontrolled by one single water authority.• All building plans must provide for rainwaterharvesting structures before applications areaccepted.• There should be a ban on permitting rainwaterto be mixed with sewer or septic tanks.• A central rainwater harvesting fund can be set

Fig. 1.5

up by the union water resources ministry offeringfunds on loan-cum-grant basis for the promotion ofrainwater harvesting.• Rainwater harvesting should be viewed by thesociety as a means of provision of water andprevention of flooding of low-lying urban areas.• One of the most effective means of encouraginghousehold and community participation is throughfinancial instruments such as water tariffs andproperty tax assessments.• Water conservation may be included in thecurriculum of the school• The Central Govt. should take up and declarethe rain water harvesting as the national program.• Annual national and state awards should beannounced on recognition of outstanding work inwater conservation.

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ConclusionThe scarcity of water has gained global

attention. The developing countries due to lack ofexpertise, funds, national policies, public awarenesscan not do much about this complicated problem.The efforts are being taken by the NGOs and otherorganizations from the micro level. The municipaloffices, town planners of the urban sectors arechanging their outlook positively towards meetingwater scarcity of the future generations. That is auseful step!

References(1) NGOs from Sangli (Maharashtra) , Ref. No. 0233-2322412(2) “Making water everybody’s business, Practice andPolicy of water harvesting” Edited by Anil Agarwal, SunitaNarain and Indira Khurana CSE publication.

12. Water Harvesting : Limitations in Implementation

*Y. Arunakar Reddy

*Associate Professor in Civil Engineering, Swami Ramananda Tirtha Institute of Science & Technology,Nalgonda, Andhra Pradesh. E-mail:[email protected]

IntroductionThe origin of the term “water harvesting” is

not known, but it was probably first used by Geddesof the University of Sidney. He defined waterharvesting as “the collection and storage of any farmwaters, either runoff or creek flow, for irrigationuse.” Several modifications of the definition havebroadened the term to mean “the process ofcollecting natural precipitation from preparedwatersheds for beneficial use”.

AbstractSince water harvesting depends on natural rainfall, it is no more reliable than the

weather. Without adequate storage facilities the system will fail in draught years. In locationswith less average annual rainfall, water harvesting will probably never be economicallyfeasible. Lack of rainfall data in many areas makes it very difficult to properly design awater harvesting system.

Poorly designed and managed water harvesting systems can cause soil erosion, soilinstability, and local flooding. All catchments require a certain amount of maintenance tokeep them performing properly which may include occasional patches, weed control, cleaningtrash from screens, seal coats, or complete reshaping.

A water harvesting system must withstand weathering and some foot traffic. Somemay require fences. Contamination of the water must be constantly considered. Discoloredor contaminated water will require treatment before it can be used for human consumption.

To day no one water harvesting method or material has proven suitable for all areas,soils, and climatic conditions. Another problem is the variability in the quality of somematerials, even though they may meet existing manufacturing specifications. This has beenparticularly true for artificial rubber sheeting, since some batches have proven very effectiveand durable, whereas others, with the same specification, have failed in a short time.

Design of water harvesting system has received less attention than methods ortreatments for increasing runoff from the soil surface. Most design procedures are limitedin application because of constraints mentioned in the above paragraphs.

This paper reviews all the above constraints in implementation of water harvestingsystem with examples.

Ancient HistoryAlthough the term “water harvesting” is

relatively new, the practice is ancient. Shanan,Evenari, and Tadmor excavated runoff farms thatwere used over 3,000 yrs ago for several centuriesin what is now the Negev Desert of Israel. This areawas intensively cultivated by an irrigation systemwhich collected the meager rainfall by clearing largehillside areas of rocks, smoothing the soil, andconcentrating the runoff by a system of contour


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ditches. The runoff water was used to irrigate a muchsmaller lower-lying area. By the time of the Romanoccupation these runoff farms had evolved intorelatively sophisticated systems covering about300,000 ha (740,000 acres) of the Negev Highlands.After the Arab conquest, the ancient desertagriculture in this area slowly disintegrated.

There is evidence that less complicated systemswere used about 700 to 900 yrs ago by the Indiansof the southwestern United States, particularly inthe four corners of Arizona, Utah, Colorado, andNew Mexico.

Recent DevelopmentCollection and storage of runoff from roofs of

houses is a more recent practice that is still used insome regions of the world. Some of the firstcatchments build specifically to collect water wereroof – like structures built in Australia in the early1930’s using galvanized sheet iron on a woodenframe. Sheet metal was also used for othercatchments built in Australia at about the same time,but the metal sections were placed directly on thesoil surface and anchored with spikes.

The development of the most widely used typeof catchment was reported by the Public WorksDepartment of Western Australia in 1956. Thesecatchments were called “roaded catchments”because the soil was graded into a series of parallelroadways or gently sloping ridges that drained intothe ditches separating them. These ditches carriedthe collected water to a storage reservoir by way ofa collection ditch which ran perpendicular to theroadways. Several thousand acres of thesecatchments have been installed in the relativelyuniform topography of Western Australia where soilsoften contain significant clay layers which areexposed and compacted and provide a rather lowinfiltrating surface. Most of these catchments havebeen used to provide farm water supplies, althoughsome are used for municipal water supplies.

In the United States water harvesting beganduring the 1940’s and early 1950’s when severalsmall sheet steel and concrete catchments were builtto provide drinking water for livestock and wildlife.Of considerably more impact was the pioneeringwork of Lauritzen in the 1950’s in which plastic andartificial rubber membranes were evaluated forconstructing catchments and reservoirs. This work

served as the basis for installing numerous butylrubber catchments and storage bags, including over300 installations in Hawaii and other pacific islands.

In 1958 and 1959 two ancient farm systems inIsrael were restored to study the hydrology of thedesert catchments and the water harvestingtechniques of the ancient farmers.

In the 1960’s Myers and Cluff in the UnitedStates and Hillel in Israel initiated research programsto devise methods of waterproofing the soil surfaceand using soil as the supporting structure. Myer’sgroup developed methods using sprayable asphaltcompounds, plastic and metal films bonded to thesoil, soil compaction and dispersion, and field-fabricated asphalt fiberglass membranes. Cluffconcentrated on using sodium salts to seal the soiland on gravel-covered plastic membranes. Hillelinvestigated several soil treatments, like crude oiland water repellants, but worked primarily on soilsmoothing and crusting.

Present Status and PotentialResearch on ways to increase runoff by soil

treatments is presently confined to a few U.S.researchers. Although both Israeli and Australianresearchers are investigating the use of fuel oils andasphalt on a small scale, their major emphasis isrunoff farming and roaded catchments, respectively.

As yet water harvesting is not accepted as acompetitive method of providing water supplies,although over 3,000 water harvesting systems havebeen installed around the world. Most catchmentsare the roaded catchments type and are used inWestern Australia where private farms have suppliedthe capital for installation. In the U.S. catchmentshave been built almost exclusively on public landsby government agencies or research organizations.Despite the rather slow acceptance of waterharvesting to provide water supplies, its potentialfor providing economical water is still tremendous.

When water harvesting techniques are used,available water supplies can be based onprecipitation rather than stream flow or groundwater. This is true for both arid and humid areas.Hawaii and Jamaica are two areas using waterharvesting techniques developed by researchers inarid parts of the world. For example, a 0.6-hacatchment in Manchester, Jamaica, provides morethan 245,000 1/day of water during a year of average

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rainfall.Water harvesting will never be used in some

areas because other water sources are moreeconomical, or because the annual precipitation isvery low. However, water harvesting can often meanthe difference between life and death, thus makingits economic aspects of minor importance.

Methods of HarvestingA wide variety of methods and materials have

been used to increase precipitation runoff intostorage facilities. Some materials, like concrete andsheet metal, can be used in almost any situation.However, the most economical system for aparticular site can be determined by evaluatingseveral factors, like soil type and depth, accessibilityto equipment, climatic variables, vegetation, labourand material costs, and availability of treatmentproducts. Whatever treatment or method is used,some maintenance will be required to insureoptimum performance.

For discussion, the methods used to increaserunoff can be divided into four general categories:vegetation management, land alteration, chemicaltreatments, and soil covers.

Vegetation Management : A summary of studiesconducted throughout the world indicates that runoffcan be increased by vegetation management fromareas with precipitation in excess of 280 mmannually. However, the conversion efficiency forproducing extra water increases as rainfall increases,at least up to 860 mm/yr; therefore, conversions atlower rainfall values may not be economical.Potential water yield increases depend upon thepercent of total precipitation occurring as snowfall,the type, depth, and slope of the watershed soil, andthe varieties of vegetation with their associatedevapotranspiration rates, which can be managedconsidering all other constraints. Besides increasingwater yield, vegetation management on watershedscan improve wildlife habitat, forage production, andrecreation activity.

Land Alteration : Often the simplest and leastexpensive method of water harvesting is to constructwalls or ditches to collect runoff from existingnatural or manmade catchments like large rockoutcrops, highways catchments like large rock

outcrops, highways, airports, and parking lots.Chiarella and beck described a highway catchmentsystem in Arizona, used for livestock drinking waterthat has been used for over 16 yrs with no observeddetrimental effect to livestock. According to Evans,Woolhiser, and Rauzi, the interstate highway systemin Wyoming would provide 2 ha/km of catchment.Assuming a 90% catchment efficiency, the watersupply from a 250-mm rainfall zone would be almost4,700,000 1/km.

For land where rock outcrops or highways arenot available, sometimes a water supply can bedeveloped by simple land alteration treatmentswhich increase the runoff from the soil surface. Landclearing is probably the least expensive treatment,but the increase in runoff is often negligible, unlessstorms are of high intensity of long duration.Because small precipitation events do not usuallyproduce sufficient runoff, rather large catchment andstorage facilities must be constructed to insure anadequate water supply to carry over between thelarge runoff events.

Another simple treatment is constructingcontour ditches to collect runoff from hillsidesbefore it reaches natural channels or infiltrates intothe soil. This was practiced by ancient people whoonce lived in what is now Mesa Verde NationalMonument in southwestern Colorado.

The “roaded catchments” discussed previouslyare a more elaborate method of land alteration. Ithas been estimated that over 2,500 of this type ofcatchment have been built in Western Australia.

Soil erosion is a potential problem with all ofthe land elaborate methods. Hollick suggests thatmaximum nonerosive slopes should be used toincrease runoff. However, he indicated that nouniversal method exists for predicting the maximumnonerosive slope, thus each site must be fieldevaluated.

Chemical and Physical Soil Treatments : Treatingsoil surfaces with materials to prevent water fromsoaking into the soil is an intriguing approach tobuilding efficient and low-cost catchments. Runofffrom bare soil can often be increased by dispersingits aggregated particles with sodium salts to reducepermeability. Hillel et al. in Israel, and Myers inArizona, were able to increase runoff by treatingcleared and smoothed sandy-loam and clay-loam

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soils with sodium carbonate. Both found thattreatment effectiveness was lost in about 1 yr anderosion was excessive. The same treatment has beenvery successful for sealing earthen stock tanks onsome soils where erosion is no problem.

High-rate applications of sodium chloride haveproven considerably more successful on aWhitehouse loam soil in the Tucson area. Here thesoil was cleared and smoothed and 11,000 kg/ha ofgranulated salt was mixed into the upper 5 cm ofsoil. The soil was later compacted after a couple ofsmall rains. Over 50% runoff has been obtainedduring the 3 yrs of records, with no deterioration orsalt movement noted.

A silicone water repellant treatment on loamysand in Arizona produced 90% runoff during thefirst year, but runoff gradually decreased to 60%after 4 yrs.

Care must be used in designing silicone - andsalt – treated catchments since increased runoff cancause excessive erosion. Silicone treatments provideno apparent stability, and stabilizing effects of salttreatments have been limited to certain sandy loamsoils.

A paraffin wax treatment on a sandy loam soilhas produced 90% runoff on test plots for over 2years with no visual signs of deterioration. Themolten paraffin penetrates the soil up to 25 mm andtends to stabilize the soil particles as it solidifies.However, a 0.2-ha field catchment treated withparaffin was no longer water repellant or stable afterfreezing and thawing with a light snow cover.Although laboratory tests in a freeze-thaw chamberconfirmed the loss of effectiveness for this soil, twoother operational catchments on sandy soils inArizona have survived a winter of freezing andthawing with no apparent damage. The lower endof one catchment did erode somewhat when the finesoil was disturbed during construction. Laboratorytests indicated that hot summer temperatures mayregenerate the wax treatments after freeze-thawdamage on some soils. These tests also indicatedthat wax treatments were not effective on certainsoils under any climatic conditions; therefore, moreeffectively treated with wax.

Several researchers have reported using fueloil to reduce infiltration. All of the studies indicatedthat initially the oil did reduce infiltration, butcompletely deteriorated within to 3 yrs, depending

on the soil and the oil used. Rawitz and Hillel foundthat retreatment each 2 years improved runoff yieldabove initial treatment values.

Soil Covers. – Soil covers are treatments thatcan generally be applied to a wide range of soil types,since they only use the soil as a supporting structureand do not depend on its properties to provide waterrepellency.

Asphalt pavements for water harvesting wereconstructed by spraying asphalt compounds onnonswelling soils. Another, more durable type ofasphalt catchment was made by placing a layer offiberglass or polypropylene matting on the surfaceand spraying it with asphalt. A seal coat of asphaltand a protective cover of special paint produced avery durable and efficient catchment. The mattingserves as a reinforcing fabric, and the asphalt as awater-proofing agent. The paint extends the periodbetween maintenance retreatments by protecting theasphalt from sunlight, and reduces runoff waterdiscoloration. This type of catchment can beinstalled over almost any soil and requires onlyminimum surface preparation.

Thin plastic films have been used as groundcovers, but they were easily destroyed by wind anddeteriorated rapidly under exposure to solarradiation. Cluff developed a unique method ofutilizing plastic’s relatively low cost and high water-proofing characteristics. He developed equipmentto install plastic film and cover it with a layer ofsmall gravel. The gravel protects the plastic againstboth wind and weathering damage; however, thegravel also reduces the runoff efficiency by retainingpart of the water which is then lost to evaporation.These catchments are useful where gravel isavailable and a large portion of the annual rainfalloccurs as storms larger than 2.5 mm. A more recentcatchment treatment developed by Cluff isconstructed by spraying soil with a tack of asphalt,followed immediately by a 4-mail layer ofpolyethylene plastic. After the plastic is coated withan additional asphalt layer, rock chips are added asa top cover. This catchment can be applied to a widerange of soil types and yields about 95% of therainfall runoff. A similar catchment using standardroofing paper and procedures, but applied to the soilsurface, has remained in good condition after 6 yrsand yields about 80% runoff.

Artificial rubber sheeting has probably been

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most widely used as a ground cover treatment.Several rubber catchments have been used for over20 yrs in the United States, and over 300 additionalrubber catchments or storage units have beeninstalled in Hawaii and other Pacific islands duringthe past 15 yrs. When correctly installed andmaintained, good rubber sheeting is an efficientcatchment material that provides high quality water.Problems encountered with its use have beenattributed to improper installation, lack ofmaintenance, poor quality material, or animal anddamage. Artificial rubber catchments have theadvantage of being rather easily transportable andsimply installed once the site has been prepared.

Corrugated sheet metal, one of the firstcatchment materials used for collectingprecipitation, has been used continually through theyears, although high costs have restricted its use.Some early sheet metal catchments were built aboveground on a roof-like framework. Many catchmentsfailed when the framework deteriorated or collapsedunder heavy snow loads. Sheet metal catchmentsbuilt on the ground have proven very durable andessentially maintenance free. Their runoff efficiencyis perhaps the highest of any catchment material,and they have often produced runoff from dew. Ifprotected from corrosion, sheet metal can be usedon almost any soil type and can provide aneconomical source of high quality water underpresent economic conditions.

Use of concrete as a catchment material hasbeen limited, mainly because of its high cost.Concrete catchments require more maintenance andhave lower runoff efficiency (60 to 80%) thenseveral other catchment materials. However, whenproperly constructed and maintained, concretecatchments are very durable and will provide yearsof service.

Storage of Harvested WaterWhere water supplies are limited and water use

rates exceed the supply rate, a means of storingharvested water becomes an essential part of thewater harvesting systems. The storage generallymeans confinement in either excavated pits or ponds,or tanks. One exception to this type of storage isdirect storage in the soil profile associated withrunoff farming. Even with runoff farming,conventionally storing water for later controlled

release to the crop may be necessary if precipitationuniformity and/or variability do not meet the croprequirements.

Storage requirements should be balancedagainst the quantity of precipitation for the area andthe reliability of receiving this precipitation. Storagerequirements can be readily estimated byconsidering the purpose for which the water will beused and the use period. The precipitation quantityand dependability generally are often more’ difficultto determine due to inadequate precipitation records.

Seepage Control. Dedrick reviewed the threemeans of storing harvested water – excavated pitsor ponds, tanks, and bags – and various methods ofcontrolling seepage losses. Excavated pits or smallponds are easily constructed in relatively flat areas,but usually a water barrier must be used to minimizeseepage losses. The type of material used maydepend on the pit site. Dedrick presented a list ofcharacteristics that should be considered whenselecting a barrier for seepage control: (a) degree ofseepage control expected; (b) resistance todeterioration by soil microorganisms, atmosphericelements, wind, and sub grade movement: (c)resistance to mechanical puncture and vermin attack;(d) toxicity; (e) installation ease; (f) transportabilityto use site; (g) maintenance requirements; and (h)economics.

Lining materials that have been used, withvarying degrees of success, can be categorized as(a) earth linings and chemical treatments –compacted earth, bentonite, chemical additives, andchemical sealants; (b) membrane and film –prefabricated asphaltic plank, hot applied asphalticmembrane, reinforced asphaltic membrane, plasticfilm, and synthetic rubber; (c) hard surface linings– Portland cement concrete, shotcrete, soil-cement,brick, and stones. The underlined materials havebeen the most successfully used in the field and arediscussed further.

Sodium bentonite, fine-textured colloidal clay,has been used to reduce seepage in coarse-texturedsoils. A good sealing bentonite must have a sufficientamount of exchangeable sodium to disperse the soilparticles. Application rates generally range from 5to 15 kg/m. Laboratory analysis, like that ofDirmeyer is recommended as a guide in classifyingthe bentonite to be used and in determiningapplication rate.

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Sodium salts have been the most successfulchemical additives used to control seepage. Sodiumcarbonate has been most effective consideringtreatment costs and ability to reduce seepage. TheSoil Conservation Service recommends sodiumcarbonate application rates of 0.5 to 1.0 kg/m whileReginato et al. presented an equation for calculatingthe amount of use. Retreatment may be requiredevery 2 to 3 yrs.

Reinforced asphaltic membrane liners consistof a substrate matting of fiberglass or polypropylenegenerally made watertight by using asphalt – eitheremulsion or cutback. Linings are fabricated in thefield and shaped like the excavated pit. They can beused as an exposed liner if properly protected frommechanical damage. Pit side slopes should not besteeper than 1:2 (vertical: horizontal). Plant growthunder the liners should be eliminated by using soilsterilants.

Plastic films of polyvinyl chloride (PVC),Polyethylene (PE), and chlorinated polyethylene(CPE) have been successful only when buried.Thickness of buried plastic film should be 0.02 to0.03cm depending on the sub grade soil. Side slopeshould not exceed 1:3. The earthen pit should beover-excavated to accommodate the cover material.The sub grade should be cleared of all sharp objects,and if too coarse, a fine-textured cushion should belaid in the pit before installing the film.Recommended cover thickness varies from 15 to30 cm with the layer next to the film not coarserthan silty sand. Plastic-lined, rock-filled, excavatedpits can be used and are a variation of the standard,buried, plastic-lined pond. The main difference isthat the pond is completely filled with rock ratherthan just covered with to protect the plastic. Freedomfrom vandalism and reduction of evaporation losses(as much as 90%) are advantages of rock-filled pitsover open storage systems.

Butyl rubber and ethylene propylene dienemonomer (EPDM) are synthetic rubber membranesused as water barriers for harvesting water. Allsynthetic rubber membranes can be used as exposedlinings, but they must be adequately protectedagainst mechanical damage and damage due tovandalism and burrowing animals. Synthetic rubbermembranes are resistant to weathering processes thatcause failure in other membrane and film materials.Rubber membranes are fabricated in numerous

thicknesses and can be either fabric-supported ornonsupport. For most excavated pits, 0.08 cm, nylon-supported liners are adequate. Reservoir side slopesshould be not steeper than 1:2. Information regardingfield installations, recommendations for use, andphysical property requirements are discussed inseveral publications.

Vertical-walled tanks have advantagesunattainable with excavated pits including: the ratioof water volume stored to water surface area ismaximum when the walls are vertical; evaporativecontrol devices, like floating covers, can be usedmore effectively and efficiently; and maintenancerequirements are generally low and repair is easy.One main disadvantage of vertical-walled tanks isinitial cost; however, on an amortized basis theyearly cost may be lower than some low-initial-coststorage systems. Materials successfully used inconstructing tank walls include Portland cementconcrete; plastered concrete and metal. The bottomof the tanks has been made watertight by usingpuddle clay, bentonite, sodium salts, concrete, metal,and flexible membranes.

Storage bags constructed of butyl-coated nylonhave been placed in excavated pits or basins. Thesestorage systems are completely closed and bothseepage and evaporation losses are controlled. Theirmain disadvantages are susceptibility to mechanicaldamage, vandalism, and vermin attack.

Evaporation Control. — Cooley has discussedevaporation suppression method. Many methodshave been investigated and can be categorized byenergy-reducing treatments (energy involved in theevaporative process) like (a) changing the watercolor, (b) using wind barriers, (c) shading the watersurface, and (d) floating reflective covers. Of thefour energy-reducing categories, floating covershave been most widely researched and certainmaterials seem most promising for use in waterharvesting storage facilities. These include coversof continuous paraffin wax, polystyrene rafts, andformed rubber.

The paraffin wax, like that used for canning,melts at 128 to 130 F and forms a continuous coverduring summer months. The wax can either beplaced on the surface as blocks which will later bemelted by the sun to form a wax layer or meltedwith a heater and sprayed or poured on the water.Polystyrene rafts are constructed of 1.2 X 1.02 cm

75

sheets of expanded polystyrene, 25mm thick, coatedwith emulsified asphalt and covered with a layer ofchips. They are then coupled together using a clampmade of PVC pipe. An outer frame of 32 – mmdiameter PVC pipes is used as a bumper for the rafts.Continuous covers of low-density, closed-cellsynthetic rubber sheeting, available as 1.2-m wideroll stock, have been fabricated for use on waterstorage tanks. Covers have been fabricated from 5-and 6-mm thick material.

All three covers – continuous paraffin wax,polystyrene rafts, and foamed rubber – reduceevaporation by 85% to 95%. The cost of water savedin high evaporation areas compares favorably withalternate water sources. Wind damage to floatingcovers can be a disadvantage. Joining thepolystyrene rafts together helps to minimize the windproblem, as does maintaining an adequate freeboardwith the foamed rubber. The wax covers havewithstood winds up to 22 m/sec on a small tank withonly 25 mm freeboard.

SummaryWater harvesting is an ancient art used by

farmers in the Negev Desert of Israel over 3,000 yrsago where they cleared hillsides to increase rainfall-runoff and directed the water to cultivated fields inthe valleys. This practice was then essentiallyabandoned until the early 1930’s, except forcollecting rainfall from rooftops in some areas.Although revival of water harvesting techniquesbegan in the early 1930’s, most activity in bothconstruction and research did not begin until the late1950’s. even this research effort and the developmentof new materials have not yet produced widespreaduse of water harvesting methods to provide watersupplies, although there is still a potential foreconomically collecting water in many areas of theworld.

The particular water harvesting method usedto collect precipitation depends on several factors,including soil type and depth, vegetative cover,surface roughness and slope, climatic factors, land,labour, and material costs, water use rate anddistribution, water quality desired, and availabilityof materials. All of the commonly used methods fallinto one of four categories — vegetationmanagement, land alteration, chemical or physicalsoil treatments, or soil covers.

Vegetation management methods have beenapplied to larger areas than the other waterharvesting techniques. Annual precipitation inexcess of 280 mm is generally required to assuresuccessful vegetation management results, andpotential for increasing runoff yield increases asannual precipitation increases. Land alterationmethods are especially attractive where imperviousareas already exist (highways, airports, rockoutcrops, etc.), and only collection and storagefacilities are required. Land alteration techniquesare also economically feasible in areas where laborcosts are low and soil conditions are suitable.Chemical and physical soil treatments, like salts,silicones, and waxes, have been applied successfullyto certain soils, but more research is required todelineate the conditions under which each can beused. Soil covers are not generally restricted by soiland climatic conditions; however, initial cost of thesystem will generally be higher than for the othermethods discussed. Regardless of the material ormethod used, erosion protection, routinemaintenance, and protection of the catchment andstorage should be considered.

Water collected from the catchments can bestored in the soil itself (as in runoff farming) or inexcavated pits or ponds, bags, or tanks. Sophisticatedcomputer models and practical experience have beenused to provide design standards for constructingand optimum sizing of catchment areas and storagefacilities.

Water harvesting systems may provide the onlysource of water in some areas and can provide alow energy input, economical water source in manyothers. The water obtained from water harvestingsystem can be used to increase the productivity ofrangelands of proper management practices arefollowed. Although it is very useful in many areas,water harvesting depends on natural precipitationand is, therefore, limited to areas where precipitationis sufficient and variability is not excessive.

References• American Society of Agricultural Engineers,“Installation of Flexible Membrane Linings,“Agricultural Engineers Yearbook, ASAERecommendation: ASAE R340, American Societyof Agricultural Engineers, St. Joseph, Mich., 1974.• Baker, James W., “Polypropylene Fiber Mat

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and Asphalt Used for Oxidation Pond Linear, “Waterand Wastes Engineering, Vol.7 No. 11, 1970, F-17-21.• Burdass, W.J., “Water Harvesting for Livestockin Western Australia, “Proceedings of theWater Harvesting Symposium, U.S. Department ofAgriculture, Agricultural Research Service, WesternRegion, ARS W-22, Feb., 1975.• Burgy, R.H., and Papazifiriou, Z.G. “Effects ofVegetation Management on Slope Stability,“presented at the January 25, 1971, Water ResourcesCenter Advisory Council Meeting, held at LosAngeles, Calif.• “Catchment Areas for Livestock Water,” SoilConservation Service, Wyoming EngineeringStandard, 701-WY, REev. Jan., 1968.• Chiarella, J.V., and Beck, W.H., “WaterHarvesting Catchments on Indian Lands in theSouthwest,” Proceedings of the Water HarvestingSymposium, U.S. Department of Agriculture,Agricultural Research Service, Western Region,ARS W-22, Feb., 1975.• Cluff, C. B., “Water Harvesting Plan forLivestock of Home,” Progressive Agriculture inArizona, Vol. 19, No. 3, 1967.

• Cluff, C. B., “Low-Cost Evaporation Controlto Save Precious Stock Water, “Arizona Farmer –Ranchman, Vol. 51, No. 7, July 1972.• Cluff, C. B., “Plastic Reinforced AsphaltMembranes for Precipitation Harvesting andSeepage Control, “Proceedings of the 11th NationalAgricultural Plastics Conference, San Antonio, Tex.,1973.• Cluff, C.B., and Dutt, G. R., “Using Salt toIncrease Irrigation Water, “ProgressiveAgricultural in Arizona, Vol. 18, No. 3, 1966.• Dedrick, A. R., “ Rain trap Performance on theFishlake National Forest, “ Journal RangeManagement, Vol. 26, No. 1, 1973.• Frasier, G. W., ed., “Concluding Remarks,“Proceedings of the Water Harvesting Symposium,U.S Department of Agricultural, AgriculturalResearch Service, Western Region, ARS W-22, Feb.,1975.• Frasier, Gary W., Myers, Lloyd E., and Griggs,John R., “Installation of Asphalt – Fiberglass Liningsfor Reservoirs and Catchments, “WCL Report 8,U.S. Department of Agricultural, U.S. WaterConservation Laboratory, 1970.

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1.0 Introduction :Rapid industrial development, urbanization and

increase in agricultural production have led tofreshwater abstraction in many parts of the countryas well as of the world. As the recharging of thegroundwater is not adequate, there is a rapiddecrease in groundwater level in several parts ofthe world. In view of increasing demand of waterfor various purposes like agricultural, domestic andindustrial etc., as well as unpredictable monsoonrainfall, a greater emphasis is being laid now-a-daysfor re-use of waste water. It has become an urgentneed of this century. Advancement in pumpingtechnology is extensively used in extracting ground

13. Roof Top Rainwater Harvesting for Artificial Recharge toGround Water : An Urgent Need of Present Century

* P. K. Singh **Bhaskar Singh **B. K. Tewary

* Scientists **Research Intern, Geo-environment Division, Environmental Management GroupCentral Mining Research Institute, Barwa Road, Dhanbad, Dhanbad- 826001 (Jharkhand)

Abstract :The water has been harvested in India since antiquity. Evidence of this tradition

can be found in ancient texts, inscriptions, local traditions and archaeological remains.The Puranas, Mahabharata, Ramayana and various Vedic. Buddhist and Jain textscontain several references to canals. tanks, embankments and wells.

Overexploitation of groundwater resources is increasingly being recognized as amajor problem. Despite being one of the wettest countries of the world, India’s growingwater shortage has reached alarming proportions. Over the last few centuries, arange of techniques to harvest every possible form of water has been developed.Technically speaking, water harvesting means capturing the rain where it falls, orcapturing the run-off in one’s own village or town. So, the need of roof top rain waterharvesting has become an urgent demand of the present century.

The amount of water harvested depends on the frequency and intensity of rainfall,catchments characteristics, water demands and how much runoff occurs & how quicklyor how easy it is for the water to infiltrate through the subsoil and percolate down torecharge the aquifers. Moreover, in urban areas, adequate space for surface storageis not available and water levels are deep enough to accommodate additional rainwater to recharge the aquifers, so the roof top rain water harvesting is ideal solutionto solve the water supply problems.

The present paper focuses in brief about the components of the roof top rainwater harvesting structure, types of recharge structures and the benefits of the system.

water from the deepest portions of the earth.Thus, the knowledge on the several traditional

water harvesting processes, storage facilities,practices and their significance to the present daysituations has become necessary in the presentcentury. It is estimated1 that 8 billion people (globally)are to be fed by the end of the first quarter of the21st century. This effort requires utilization of allwater resources intelligently. For this, there is a needto collect, conserve and use critical water resourcesjudiciously.

In this context, roof top rainwater harvestingcan become popular technique to improve therecharge regionally and globally. Moreover, in Urban


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Areas, adequate space for surface storage is notavailable and water levels are deep enough toaccommodate additional rain water to recharge theaquifers, so roof top rain water harvesting is idealsolution to solve the water supply problems.

2.0 Urgency of the Process:A comparison of water levels from 1960 to 2001

shows that water levels in major part of country aresteadily declining because of over-exploitation.During 1960, in Delhi, the ground water level wasby and large within 4 to 5 meters and even in someparts water logged conditions existed. During 1960-2001, water levels have declined by 2- 6 m. in mostpart of the alluvial areas. Decline of 8-20 m. hasbeen recorded in south-west district and in southdistrict the decline has been 8-30 m. Areasregistering significant decline fall mainly in south andsouth-west districts and have been identified aspriority areas for taking up artificial recharge toground water by roof top rain water harvesting.

Thus, though the concept of roof top rainwaterharvesting is an age old one, but systematic collectionand recharging to ground water is of recent times.As surface water sources fail to meet the risingdemands of water supply in urban areas, groundwater reserves are being tapped and over-exploitedresulting into decline in ground water levels anddeterioration of ground water quality. This precarioussituation needs to be rectified by immediatelyrecharging the depleted aquifers.

3.0 Typical Roof Top Rainwater HarvestingStructure:

A typical roof top rainwater harvesting systemcomprises of:a) roof catchmentsb) guttersc) down pipesd) rain water/storm water drainse) filter chamberf) ground water recharge structures like pit,trench, tube well or combination of above structures.

4.0 Methods of Groundwater Recharge:For Rainwater Harvesting System following

structures are required:a) Recharge Pitsb) Recharge Trenches

c) Abandoned Dugwellsd) Hand Pumpse) Recharge Wellsf) Recharge Shaftsg) Lateral Shafts With Borewells

a) Storage Tanks :for harvesting the roof top rain water, the

storage tanks may be used.these tanks may be constructed on the surface

as well as under ground by utilizing local material.the size of tank depends upon availability of

runoff & water demand.after proper chlorination, the stored water may

be used for drinking purpose.

b) Recharge Pitsrecharge pits are constructed for recharging

the shallow aquifers.these are constructed 1 to 2 m. wide and 2 to 3

m. deep which are back filled with boulders, gravels& coarse sand.

the size of filter material is generally taken asbelow:

coarse sand : 1.5 - 2 mmgravels : 5 - 10 mmboulders : 5 - 20 cmthe filter material should be filled in graded

form. boulders at the bottom, gravels in between& coarse sand at the top so that the silt content thatwill come with runoff will be deposited onthe top of the coarse sand layer and can easily beremoved.

if clay layer encountered at shallow depth, itshould be punctured with auger hole and that augerhole should be refilled with fine gravel of 3 to 6 mmsize.

c) Trenchesthese are constructed when the permeable

strata is available at shallow depths.trench may be 0.5 to 1 m. wide, 1 to 1.5 m.

deep and 10 to 20 m. long depending uponavailability of water.

these are back filled with filter materials. incase of clay layer encountered at shallowdepth,

the number of auger holes may be constructed& back filled with fine gravels.

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d) Abandoned Dug wellsexisting abandoned dug wells may be utilised

as recharge structure after cleaning and desiltingthe same.

for removing the silt contents, the runoff watershould pass either through a desilting chamberor filter chamber.

e) Abandoned Hand pumpsthe existing abandoned hand pumps may be

used for recharging the shallow / deep aquifers,if the availability of water is limited.

water should pass through filter media beforediverting it into hand pumps.

f) recharge wellsrecharge wells of 100 to 300 mm. diameter

are generally constructed for recharging thedeeper aquifers and roof top rain water is divertedto recharge well for recharge to ground water. Therunoff water may be passed through filter media toavoid choking of recharge wells.

g) Vertical Recharge shaftsFor recharging the shallow aquifers which are

located below clayey surface at a depth of about 10to 15 m, recharge shafts of 0.5 to 3 m. diameter and10 to 15 m. deep are constructed depending uponavailability of runoff. these are back filled withboulders, gravels & coarse sand. For lesser diametershafts, the reverse / direct rotary rigs are used andlarger diameter shafts may be dug manually. In upperportion of 1 or 2 m depth, the brick masonry work iscarried out for the stability of the structure.

h) Shaft with Recharge wellIf the aquifer is available at greater depth say

20 or 30 m, in that case a shallow shaft of 2 to 5 mdiameter and 5 to 6 m deep may be constructeddepending upon availability of runoff. inside the shaft,a recharge well of 100 to 300 mm diameter isconstructed for recharging the available water todeeper aquifer. at the bottom of the shaft a filtermedia is provided to avoid choking of the rechargewell.

i) Lateral trench with bore wellsFor recharging the upper as well as deeper

aquifers, lateral trench of 1.5 to 3 m. wide & 10 to

30 m. long depending upon availability of water withone or more bore wells may be constructed. thelateral trench is back filled with boulders, gravels &coarse sand.

5.0 Benefits of Rooftop Rainwater HarvestingStructurea) An ideal solution of water problem in areashaving inadequate water resources.b) The ground water level will rise.c) Mitigates the effects of drought.d) Reduces the runoff which chokes the stormwater drains.e) Reduces flooding of roads.f) Quality of water improves.g) Soil erosion will be reduced..6.0 Design Criteria of Recharge Structures

Recharge structures should be designed basedon availability of space, availability of runoff, depthto water table & lithology of the area.

Assessment Of RunoffThe runoff should be assessed accurately for

designing the recharge structure and may beassessed by following formula.

Runoff = Catchment area * RunoffCoefficient * Rainfall

Runoff CoefficientsRunoff coefficient plays an important role in

assessing the runoff availability and it depends uponcatchment characteristics. General values aretabulated below which may be utilised for assessingthe runoff availability.

Type of catchment Runoff coefficient

Roof top 0.75 - 0.95Paved area 0.50 - 0.85Bare ground 0.10 - 0.20Green area 0.05 - 0.10

Design ConsiderationsThree most important components, which

need to be evaluated for designing the rainwaterharvesting structure, are:1. Hydrogeology of the area including nature and

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extent of aquifer, soil cover, topography, depth towater levels and chemical quality of ground water2. Area contributing for runoff i.e. how much areaand land use pattern, whether industrial, residential

or green belts and general built up pattern of thearea.3. Hydrometeorological characters viz. rainfallduration, general pattern and intensity of rainfall.

Schematic sketch of Rain Water Harvesting in Rural Areas

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8.0 Conclusions :Thus, water has been harvested in India since

antiquity. Evidence of this tradition can be found inancient texts, inscriptions, local traditions andarchaeological remains. The Puranas, Mahabharata,Ramayana and various Vedic. Buddhist and Jaintexts contain several references to canals. tanks,embankments and wells.

Overexploitation of groundwater resources isincreasingly being recognized as a major problem.Despite being one of the wettest countries of theworld, India’s growing water shortage has reachedalarming proportions. Over the last few centuries, arange of techniques to harvest every possible formof water has been developed. Technically speaking,water harvesting means capturing the rain where itfalls, or capturing the run-off in one’s own village ortown. Thus, the role of Institution of Engineers(India), Nagpur Local Centre is worthy in thisdirection.

References :a) Nagrajan R. : Water ; Conservation, Use andManagement for Semi-arid Region: CapitalPublishing Company;2006.b) Athavale, R.N. Water harvesting andsustainable supply in India, Centre forEnvironmental Education and Rawat Publications;2003c) Natarajan, P.M., & Kallolikar S. Rain WaterHarvesting New Approaches For SustainableWater Resources Development, Sarma SanitoriumPress; 2004d) http://www.rainwaterharvesting.org/urban/Howtoharvest.htme) h t t p : / / a k a s h - g a n g a - r w h . c o m / RW H /WaterHarvesting.htmlf) http://www.gdrc.org/uem/water/rainwater/introduction.htmlTodd, D.K. (1980). Groundwater Hydrology.Second edition., John Wiley & Sons, New York.

Roof Top Rain Water Harvesting Structure

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IntroductionIndia receives good amount of rainfall. But

the rainfall is highly erratic in nature. It is not evenlydistributed over the entire area and over the period.India have distinct rainy season. In most part of thecountry the annual rainy days varies from 10 to 45.As soon as the rains are over, water scarcity starts.The ancestors realize that, harvesting the water inrainy season will be use full in rest period of theyear. They have developed varies techniques toharvest the water because they knew that withoutharvesting the water life is difficult to survive. Thereare evidences that, during Harappan period, therewas very good system of water management ascould be seen in the latest excavation at Dholavirain Kachch. The people use to manage waterresources considering it as part of the nature, whichis essential for their survival. This could be seenfrom the rainwater harvesting structures in the lowrainfall areas of Rajasthan, harvesting springs inhilly areas and mountainous region and percolation

14. Roof Top Rain Water Harvest- A Long Lasting Solution toDrive away the Need of Water Tankers

*Mrs. Charu Bhavsar **Pradeep Bhalge

AbstractWater has been harvested in India since antiquity. Roof top water harvesting

techniques are not new for Indians. Numerous documentary and filed evidences aboutthe water harvesting techniques used by the ancestors exist in India. For general,Maharashtra receives a good amount of annual rainfall. But the Government has tosupply drinking water by the water tankers to numerous villages and wadies. Many ofthe wadies or tandas are situated in remote places. In such cases drinking water cannotbe supplied to the thirsty people by tankers or by any other means. The water suppliedby the Tankers may not be either pure or sufficient. There is a need to think; ‘Is itnecessary to supply the drinking water by Tankers?’ The answer is ‘not in all thecases’. Roof top rainwater is the best solution to solve all the problems discussed above.This paper will illustrate the drinking water needs, computation of the quantity of theannual rain water from the roof top, methods and type of storages in practice, care tobe taken to maintain the purity of the rain water harvested, and the merits and demerits.

ponds and tanks in southern India. In Tamil Nadu,the ancient people stored rainwater in public placedseparately one for drinking purposes and anotherfor bathing and other domestic purposes. They alsoformed percolation tanks or ponds, for the purposeof recharging irrigation or domestic wells. Theyperiodically clean the waterways so as to get cleanwater throughout the year. These are instances inthe history that people constructed crude rubblebunds across river courses either for diversion ofwater or for augmenting the ground water.

Unfortunately under the British governancesystem the wisdom of the raindrop was lost. Thetechnological interventions, which got water intoour taps, relied on large-scale water impoundmentsin the upper reaches of rivers and pushed the wisdomof the raindrop into the background. Today the needof the hour is to go back to the wisdom of ancestors,rediscover their concepts and adapt them into ourlives.

*Indian Council for water and culture; Aurangabad.**A.E.II, Water Resources Department, Government of Maharashtra.


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Traditional rainwater harvestingTraditional rainwater harvesting, which is still

prevalent in rural areas, was done in surface storagebodies like lakes, ponds, irrigation tanks, templetanks etc. In urban areas, due to shrinking of openspaces, rainwater will have to necessarily beharvested as ground water, Hence harvesting in suchplaces will depend very much on the nature of thesoil viz., clayey, sandy etc. The below listed are thevarious kinds of traditional rainwater harvestingmethods.

KUND OF RAJASTHAN

BAMBU DRIP IN MEGHALAYA

Kunds of Thar Desert :In the sandier tracts, the villagers of the Thar

Desert had evolved an ingenious system of rainwaterharvesting known as kund or kundis. Kund, the localname given to a covered underground tank, wasdeveloped primarily for tackling drinking waterproblems. Usually constructed with local materialsor cement, kund were more prevalent in the westernarid regions of Rajasthan, and in areas where thelimited groundwater available is moderate to highlysaline. Under such conditions, kund providesconvenient, clean and Sweetwater for drinking. Thekund consists of a saucer-shaped catchments areawith a gentle slope towards the centre where a tankis situated. A wire mesh to prevent the entry offloating debris, birds and reptiles, usually guard theopenings or inlets for water to go into the tank. Thetop is usually covered with a lid from where watercan be drawn out with a bucket. Kund are by andlarge circular in shape, with little variation betweenthe depth and diameter which ranges from 3-4.5 m.Lime plaster or cement is typically used for theconstruction of the tank, since stone as a buildingmaterial is not always available and is relativelymore expensive. Either of these materials can beused to plaster the horizontal and vertical soilsurfaces, although cement ensures a longer life span.The success of a kund depends on the selection ofthe site, particularly its catchments characteristics.An adequately large catchments area has to beselected or artificially prepared to produce adequaterunoff to meet the storage requirements of the kund.

Bamboo Method :In Meghalaya, an ingenious system of tapping

of stream and spring water by using bamboo pipesto irrigate plantations is widely prevalent. About18-20 liters of water entering the bamboo pipesystem per minute gets transported over severalhundred meters. The tribal farmers of Khasi andJaintia hills use the 200-year-old system. Thebamboo drip irrigation system is normally used toirrigate the betel leaf or black pepper crops. Bamboopipes are used to divert perennial springs on thehilltops to the lower reaches by gravity. The channelsections, made of bamboo, divert and convey waterto the plot site where it is distributed without leakageinto branches, again made and laid out with differentforms of bamboo pipes. Manipulating the intake

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pipe positions also controls the flow of water intothe lateral pipes. Reduced channel sections anddiversion units are used at the last stage of waterapplication. The last channel section enables thewater to be dropped at the rate of 20-80 drops perminute near the roots of the plant.

Roof top rainwater harvesting and rainwaterharvesting techniques is not new

The concept of roof top rainwater harvestingand rainwater harvesting techniques is not new.Many of us feel that this tool is devised by themodern society as a tool to drought proofing. Thisis not so. Our ancestors had been doing it accordingto the means available then. At large, no of placesin India, this art and science has been practiced.The most beautiful rainwater-harvesting schemecould be witnessed at Deogiri fort. Water from theadjacent hillock was transported through an invertedsiphon of twin pipes and the mot around the hilltopfort was filled. A moat around the hill top fort isanother wonder. Transportation of water thoughinverted siphon was a unique feature. The templeswere used as roof top rainwater harvesting devices.The noteworthy example is of Minakshi temple inMadurai. If seen carefully it is seen that beautifularrangement of collection of roof top rainwaterscheme is made here. The harvested water is storedin a tank. With the advent of tap water, rainwaterharvesting has lost its importance. As our State isin a situation where efficient management of waterresources has become a necessity, rainwaterharvesting has come to limelight again. We have toresort to long-term measures in harvesting therainwater due to the growing demand. It is henceemphasized that rainwater harvesting shouldbecome an integral part of every home, society,village, city and country.

Back to the traditionIn the previous days peoples were bringing

water from the community well. The water wasdrawing from the well with the help of rope andbucket. Thus there was a limitation of drawing thewater and indirectly there was restriction on thewater use. The methods of domestic utilization weredeveloped to support the minimum use of water.For example water for mouthwash was taken in apot. The capacity of such pot was around one liter.

But taking the mouthwash under a running tap willrequire more than 15 to 20 liters of water. A bucketof 15 to 20 liters was sufficient to take bath beforethe advent of tap water, but now a day’s taking bathunder the water tap consumes 50 to 100 liters ofwater. In this way, habits of wasteful use of waterare increased in these days. With the advent of theelectric pumps the rate of withdrawal of water fromthe well is increased tremendously, resulting in todepletion of ground water level. Every year therains replenish the ground water. But due toexploitation of more water than the replenish one;peoples do not get water even for drinking insummer days. The wells and bore wells runs dry assoon as the rainy season is over. In such situationstankers are supplying water. The local leaders putlot of pressure on the government officials to supplywater tankers. It is observed that nobody worriesabout the purity of the water supplied by the tankers.Drinking the impure water leads to water borndisease. It is said that 80% of the human diseaseare due to impure water. The whole family has tosuffer when any member of their family becomesill. Especially incase of a family whose livelihoodsis depend upon the labor work, if an adult get ill,survival of his family comes in danger. All theproblems as said above can be minimized if everyfamily gets sufficient amount of pure water fordrinking. A time is now came to think that is itnecessary to use heavy cost water supply schemeseverywhere? Is it necessary to supply water bytankers? This can be achieved by adopting roof toprain water system. By adoption of the Roof toprainwater harvesting techniques, there will not beany need to supply water by tankers. Let us see thathow where and when this technique is useful.

Human water needs : Let us understand our dailyper head water requirement.Daily water need Maximum Minimum

in liters in liters

Latrine and 25 05washing mouthBath 25 10Washing cloths 25 10Food preparation 10 05and drinkingOther purpose 10 05Total 95 35

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The minimum water need is 35 liters per dayper person. Thus 175 liters water per day will besufficient for a family of five persons. Suppose theroof top area of the house is 30 sqm; and the averageannual rainfall is 700 mm. Then the roof toprainwater potential is 21000 liters. If a under groundtank of size 3m x 3m x 2.5m is constructed. Thestorage capacity of the tank will be 22500 liters.This much water will be sufficient to them for 128days. That is more than 4 months of the dry summerdays. The construction cost of the tank will bearound Rs.20000/-. With nominal maintenance thetank will serve for more than 40 to 50 years. Thusthis is a long lasting solution. The annual cost ofthe tank will be around Rs.2000/-

Thus it is seen that the cost of the underground storage tank i.e. 20000/-will be recoveredwithin five years.

Construction of Kund and such type of underground storage tanks are practiced in Rajasthan andGujarat. With these techniques they have solved thewater problems. They built a water storage tankunder the main Hall of the house. The storagecapacity is ranging from 20000 to 40000 liters. Insummer days when the wells become dry they usethe stored water. The rainwater harvesting systemis found in the house of general publics as well asin the minister’s house also. It will be interested tonote that an under ground tank was in use in thehouse at Porabandar, where Mahatma Gandhi wasborn.

Comparison of tankers expenditure with the construction cost of water storage tank

Harvesting Water at Home

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The rainwater that is harvested is pure withvirtually no impurities and is suitable for all purposes.After filtration the harvested rainwater can be putto all uses including drinking and cooking purposes.The area on which the rainwater falls is thecatchments area. The annual rainwater harvestingpotential of rooftop can be calculated by multiplyingthe area and the amount of rainfall that is receivedannually.

In rural areas, the roof top harvested rainwatercan be stored or used for recharge of ground water.This approach requires connecting the outlets pipefrom rooftop to divert the water in to a storage tankor divert it to either existing well/tube wells/borewells or specially designed wells/ structures.Following table shows the availability of rainwaterthrough Roof Top Rain Water Harvesting.

Size of down water pipeThe collection system directs the rainwater

falling over the rooftop, into the filtration system. 75to 90 mm diameter PVC pipes resistant to UV raysappear to be the best bet as down water pipes. Ofcourse, this depends upon the roof area to be

drained. 3 to 4 down water pipes seem sufficientfor 30 to 40 square meter roof areas.

FiltrationBefore the water enters the down water pipesFiltration arrangements is must. This can be archivedwith following simple methods.• Put a piece of sponge placed at the inlet of thedown water pipe.• A PVC bucket with gravel, sand & charcoal isa good filter before rainwater is stored• A PVC drum with sponge at the inlet & outletis also a filter• A small two chamber inspection/ filter tank canalso be devised• A Devas type filter is found to be useful. It iseasy to construct, maintain, and have low cost.

Water yield available in liters from the annual rainfall, roof top area

(m²) Harvested Roof Top Water in liters

Annual Rainfall in mm ..................

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The rainwater dissolves the impurities that arepresent on the surface as it flows over the roof areainto the collection system. Therefore it is advisableto keep the catchments area free of any chemical orother harmful impurities. At times, it is also advisedthat the run-off of the first few minutes of the rain

be allowed to flow out. This washes away most ofthe impurities that may be possibly present on thesurfaces.

StorageThe harvested rain shall be stored in a storage

tank. The tank can be built with locally availablematerials and traditional construction techniques.The storage tank can be constructed underground,above ground or partially above ground as shownin the following figures. Use the ground water tillit is available. Use the water stored in the tanks indry months.Depending on the amount of rainwater that needsto be harvested and the proposed end use of theharvested rainwaters, an appropriate storage orrecharge system is designed. The simple thumb rulefor that is “build a storage tank of bottom area equal

to the one third area of the roof top and the depth ofthe tank equal to three times the average annualrainfall in meter or three meter whichever is less.”For example there are three rooms in a house ofsize 3m x 3m. The total roof area will be 3no x3m x3m i.e. 27 square meter. Let the house is lies in theaverage annual rainfall of 700 mm (0.7meter). Thenfor storing the harvested roof top water construct aunder ground tank having the bottom area equal toone third the roof area i.e. 27/3=9 square meter.Keep the depth of the tank equal to 3 times theaverage annual rainfall i.e. 0.7m x 3=2.1 meter. Thusthe storage capacity of the tank will be 3 x3 x 2.1=18.9 cubic meter i.e. 18900 liters. And this muchwater will be sufficient for three most dry summermonth to a family of five members. And if used veryprecisely for drinking and cooking purpose then thismuch water will be sufficient for more than six

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months. It is interesting to note that in Bikaner areaof Rajasthan the people prefer to give harvestedrain water to an ill person than the tap water. Thusthey have very much faith on the purity of theharvested and stored rainwater. Since 1986, in 450school of Rajasthan under ground storage tank areconstructed. The total storage capacity of thesetanks is about 27 million liters. The students and thestaff have drunk the water since its inception andthere have been no complain from their teacher orparents that they have fallen ill from drinking thewater.

MaintenanceWater harvesting systems require occasional

maintenance, but this can be easily accomplished.Debris and leaves should be filtered before storingthe water by placing screens over gutters. Debrisscreens over gutters should be cleaned periodicallyand storage tanks should be drained and cleanedregularly. Water kept in tanks should be covered tominimize algae growth and eliminate the potentialfor any mosquito breeding.

Ground water recharge-Simple MethodsThe water in the premises can be harvested to

recharge the ground water. The recharging willcertainly help to increase the ground water storage.The design and the location of these rechargesystems is site specific and needs to be evolved asper the requirements.When the rainwater falls on the ground, some of itseeps into the soil but the surplus adversely flowsout as a stream or as run-off. The top soil however,can hold only a fraction of water that falls on it andthe rest gradually percolates down, depending onthe type of the soil and joins the aquifers that aregroundwater-bearing formation Artificial rechargeis a process of augmenting the underground watertable by artificial infiltration of rain water andsurface run-off.

Techniques of Rain water Harvesting.• to make more water to percolate down the soil,percolation pits are made, when there is a pavedpathway and are covered with perforated concreteslabs wherever necessary. Whenever the depth ofclay soil is more, recharge through percolation pitswith bore is preferable.

• Rooftops of houses serve as excellent andeconomical form of collection centers for rainwater.If properly diverted and used for artificial rechargeit will augment the ground water table to a sufficientextent. The roof is connected to the well through afiltering arrangement by PVC pipe. A valve systemcan be incorporated to flush the initial part of therainwater to get rid of impurities collected on theroof. Rainwater also can be collected and stored inlarge sumps to consume directly after necessarychlorination.• Bathing and washing water can be routed tothe open ground nearby to percolate down to retainthe soil moisture. The gray water can also be treatedby some water treatment methods like Soil AquiferTreatment System (SAT) and further the pretreatedwater.• The ground level near the gate should be raisedto retain as much water as possible inside thecompound. Alternatively, it is recommended toconstruct a sloping gutter across the gates and directthe rushing water towards percolation pit. Formultistoried building, it is better to direct this waterto a recharge well.• The storm drains inside the premises shouldhave boundary wall to ensure that the rain waterinstead of rushing into the drains and going as waste,stagnates over the ground for sometime and seepsinto the soil.• Wherever there is a slope, it is recommendedto construct a dwarf wall to a height if 1 ft, to avoidrun-off as well as to retain the rain water and allowfor slow percolation.• The run-off water generated in monsoonswithin an area can be well utilized for ground waterrecharging by diverting it into suitably designedrecharge structures in public parks, splay grounds,stadiums, airports, stations, temple tanks, etc.• Storm water drains should be designed in sucha way that two separate segments are made so as toaccommodate water coming from houses and fromroads. The segments on the sides of the roads shouldbe covered with perforated slabs and should havepercolation pits of depth 20 to 50 ft., depending onthe soil condition, at regular intervals.• Due to severe depletion of ground water table,many open wells, bore wells and hand pumps aregetting dried. Instead of discarding these wells, theycan be converted into useful recharge wells. Roof

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water and run-off water can be diverted into thesewells after filling the wells with pebbles and riversand. There should be an effective arrangement fordesalting before diverting the water into these wells.• It is advisable to have numerous percolationpits in agriculture lands for gradual percolation andrecharging of aquifer. Construction of small bundson slope areas slows down the run-off water andhelps easy percolation. Run-off water can bediverted into a large well through a Baby well andfiltering tank to avoid silt depositing in the well.• In open grounds, the topsoil is removed andfilled with river sand. As the river sand is looselypacked, it allows water to percolate down quickly.

Merits• It is a low cost long lasting solution supplyingpure water.• If it is made compulsory to adopt the roof toprain water harvesting then there will be no need tosupply water by tankers. This will save huge amountof money. This on other wise can be spent on thedevelopment works. This will also save the dieselindirectly foreign currency.• The rainwater harvesting system is very usefulin the remote places and in arid zone.• It is also useful in high rainfall and well aslow rainfall zones.• This can be a best solution in the areas havingsaline ground water or water containing fluorides.• It is also useful in case of flood situations as

the water sources get polluted due to entry offloodwater in to them, and other reasons. In suchconditions harvested rainwater will be the onlysource of pure water.• Combination of roof top rainwater harvestingand rain water harvesting is a long lastingsustainable solution for the drinking water crises,and to keep the tankers away.

DemeritsRoof top rain water harvesting system can not

supply water if there is no rain fall over thecatchments or the water is not stored in the storagetank, in the preceding rainy season.

ReferencesBooks1. Pani Sarvansathi, Pradeep Bhalge2. Aaj bhee khare hai talab, Anupam Misra3. Bharatiya Jal Sanskriti Sawarup Ani Vyapti,Dr. R.S.Morawanchikar4. Param vaibhavacha tappa ala, Prof.R.M.Pandav

Papers and Articles1. Glimpses of Water History of India, Dr. D.M.More2. Few Glimpses of Indian water Culture, Dr. R.S. Morawancikar3. Sankalan Pauspanyache, Pradeep Bhalge

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1. INTRODUCTIONGround water is basically a renewable

resource, but the volume of water actually storedmay vary greatly from place to place depending onphysiography, climate, hydrogeology and rate ofground water withdrawal used for various purposes.The ground water development has to be optimisedconsidering the demand and supply factors. Underutilization of available resources is not desirable asit deprives the economic development of the humanbeings. On the other hand overexploitation ofground water leads to depletions of water resourcesand scarcity in future. Available ground waterresources and potential for its augmentation needsto be assessed scientifically and understoodholistically for planning the water resourcesmanagement. This study has been done for Yavatmaldistrict on scientific lines as follows.

2. LOCATIONThe Yavatmal district lies between 19026’

N to 20042’ N Latitude and between 77018’ E to

79009’ E Longitude (Maharashtra State Gazetteer,1974) and covers an area of 13584 km2, which is4.41% of the Maharashtra state (Socio EconomicReview, 2003-04). It is one of the economicallybackward district of Vidarbha regions of the state.As per the 2001 census the district has got apopulation of 24,58,271 with a density of 181/ km2

(Census of India, 2001). Location of the area is givenin Fig 1.

3. HYDRO-GEOLOGICAL SETUP

3.1 Physiography and ClimatePhysiographically the area is mostly

undulatory dissected plateau with isolated hillsexcluding the eastern part of the district, which isplain. The district is well drained by the riversPenganga, Wardha and their tributaries namely Pus,Bembla, Aran, Arunavati, Waghadi, Khuni,Vaidharbha and Nirguda.

The climate of the district is characterizedby hot summer and general dryness except during

15. Additional Ground Water Storage Potential for Artificial Rechargein Phreatic Aquifers of Yavatmal District, Maharashtra, India

*Pandith Madhnure **Sunil Kumar Jain

* Scientist “B”, **Scientist “D” 2Central Ground Water Board, Central Region, Civil lines, Nagpur –440001For correspondence (email: [email protected] or sunilkumar_jain@ rediffmail.com)

ABSTRACTYavatmal district is mainly underlained by varied geological formations consisting ofPenganga Group, Gondwana Group, Deccan Traps and Quaternary sediments. Post monsoondepth to water level and lithological logs of exploratory wells in shallow aquifers down to20 m depth have been studied and analysed in detailed. The average tahsil wise depth towater level varies from 6 to 9 m m bgl and the available porous space for artificial rechargein unsaturated zone in phreatic aquifers varies from 0.4 to 6 m. The potential of groundwater storage by recharging the phreatic unsaturated zone is estimated to be 951.6 MCM.The drinking needs of 1,44,200 people during the 4 months of summer season can be met oradditional 1,29,500 hectors of land can be brought under assured irrigation from thisaugmented ground water resources. The undue withdrawal of ground water from the deeperaquifers containing excessive fluoride causing fluorosis can be checked in the area.KEY WORDS: Shallow aquifer, Storage potential, Depth to water level Yavatmal, Artificialrecharges potential.


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the SW monsoon. The normal annual rainfall variesfrom about 850 to 1150 mm and it increases fromNW to SE direction in the district. The temperaturevaries from minimum of 15.10C in winter andmaximum of 41.80C in summer.

3.2 GeologyArchaean rocks from the basement and are

covered by Penganga and Vindhyan group of rocks.The Gondwana group of rocks overlays these rocks.Deccan trap is spread all over the area. Finally theaction of atmosphere eroded the Deccan traps inparts, exposing the other older formations at surface.The thickness of these formations therefore variesfrom place to place and thus hydrogeology of thearea is influenced accordingly (Deshmukh, 1994).

The contact between Penganga Group ofrocks and Deccan traps is marked by unconformity.The contact between Gondwana and Deccan trap ismostly undulatory. The eastern part of the districtis traversed by numerous faults; therefore rocks ofdifferent groups are met at different altitude in thearea owing to differential subsidence or upheavalevents. The lithological geometry of the phreaticaquifers is generated exclusively based on theexploratory drilling at 51 wells is given in Table 1and plotted in Fig 2.

3.3 HydrogeologyThe Deccan traps are the predominant water

bearing formations with variations in hydrogeological properties over horizontal and verticalspace. It is followed by Gondwana formationshaving sandstone and shales sequence. ThePenganga and Quaternary alluvium aquifers arespread in limited areas but have significant rolewherever they are found. Archaean aquifers arelimited and have less significance in the area.

3.3.1 Phreatic Aquifers: Phreatic aquifers are mostproductive and occur at shallow depth, which aredeveloped by dug wells up to 20 m depth. Groundwater occurs in the weathered zone, fractures inArchaean rocks, Penganga formations, Vindhyanformation and Gondwana formations and weatheredzone, fractures and vesicular part in the basalticformations.

A comprehensive depiction of depth towater level is made by using the data of the 317

dug wells for the year 2005 (CGWB, 2006). Thedepth to water level in the phreatic aquifers variesbetween to 1.80 mbgl to 16.80 mbgl during the premonsoon season and between 0.30 m bgl to 15.15mbgl during the post monsoon season in the district.The tahsil wise average depth to water level in thearea during post monsoon season of the year 2005varies from 6 m bgl to 9 mbgl with an average of6.96 m bgl. Deep water levels are observed in Wani,Kelapur and Ghatanji tahsils. Hydrogeological mapof the district along with depth to water level(November, 2005) is given in Fig 1.

4. GROUND WATER RESOURCESThe CGWB and GSDA estimated the

ground water resources of the district based onGround Water Estimation (GEC) Methodology1997. The net annual available ground waterresources are 1278.34 MCM and the ground waterdraft is 314.35 MCM. Overall the stage of groundwater development is 24.6 % in the district (GSDA& CGWB, 2005). The tahsil wise ground waterresources of the district are given in Table 2.

Ground water development scenario variesin the district, while eastern part consisting of Wani,Maregaon, Kelapur, Ghatanji and Jhari Jamni tahsilsare the least developed tashils from ground waterresources point of view having less than 15% ofthe development. The Ralegaon, Yavatmal,Babulgaon, Kalamb and Arni are the next developedtahsils with the stage of development between 15to 25%. There is better ground water developmentin Darwah, Ner, Digras, Pusad and Umarkhed tashilswhere the stage of ground water development is 25to 40%. Maximum development of ground water is45% and is observed in Mahagaon tahsil. As perthe GEC norms all the tahsils and 64 watershedsfalls in safe category.

5. SCOPE OF GROUND WATERAUGMENTATION THROUGH ARTIFICIALRECHARGE

The ground water development scenario ofthe district is favorable for further ground waterdevelopment in years to come. However, as thedevelopment of ground water resources proceedswith increasing ground water withdrawal, thedepletion of water table will accelerate resulting intodrying or deepening of existing wells. There are

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many pockets in the district where water levels havedeepened and also certain areas lack adequatenatural replenishment. Therefore, artificial rechargemeasures would be required simultaneously so asto augment the ground water resources of the area.There is a need for assessing the scope and extentof artificial recharge potential available at presentin the area so as to make a comprehensivemanagement plans for the district. The artificialrecharge potential has been assessed accordinglyon the scientific pattern and methodology in thisstudy.

6. IDENTIFICATION OF POTENTIAL AREASFOR ARTIFICIAL RECHARGE (PHREATICAQUIFER)

The base map of Yavatmal district on 1:250,000 scale is prepared by demarcating district,tahsils boundary and major drainage. Thelithological logs of the phreatic aquifers down tothe depth of 20 meters below ground level (m bgl)are compiled and plotted on the base map (Fig. 2),as the area is developed by dug wells up to 20 mdepth. Data of 51 exploratory wells drilled byCGWB is specifically analyzed in detail for thephreatic part although their depth ranges from 17m bgl to 470 m bgl. This is superimposed on thebase map so as to account for storage potential ofdifferent strata more precisely. The aquifer geometryis also reflected from this data source. The depth towater level data of post monsoon season for the year2005 is used to assess the unsaturated spaceavailability in phreatic zone. These aresuperimposed and transferred on the base map togenerate a comprehensive map (Fig. 2).

Based on the above-mentioned information,the tahsilwise potential for artificial recharge toground water is worked out. The summarized resultsof lithology, depths to water levels are given inTable 3.

The disposition of impervious layers belowthe ground water surface has decisive role tofacilitate or to retard the recharge from rainfall orstorage tanks. A perusal of the Table 3 indicates thatthe depth of impervious formation varies from 0.75 m bgl (Darwah tahsil) to 5.6 m bgl (Digras &Arni tahsil).The unsaturated thickness of porouszone availability varies from 0.4 m (Digras and Arni

tahsil) to 6 m (Kelapur tahsil) with an average of3.16 m. It is found that only some percentage oftotal thickness of the unsaturated zone is porous andthe remaining is non porous for ground waterstorage. The percentage varies from 7% (Digras &Arni tahsil) to 67% (Kelapur tahsil) with an averageof 48%. The area having maximum thickness ofporous strata in unsaturated zone is most potentialfor ground water recharge through artificialmeasures.

The artificial recharge is targeted to raisethe depth to water level up to 3 m bgl so as to avoidthe danger of water logging. The column 7 of Table3 is worked out by subtracting column 5 fromcolumn 4 of Table 3 or the actual top imperviouslayer or 3 m whichever is more.

7. STORAGE POTENTIAL OFUNSATURATED PHREATIC AQUIFERS

The volume of water for recharging theunsaturated (dry) zone of phreatic aquifers isestimated by multiplying the tahsilwise area withthe available unsaturated thickness and the averagespecific yield of the particular strata. Thus, the totalstorage potential of phreatic unsaturated aquifervaries from 9.04 MCM in Digras & Arni tahsils to142.56 MCM in Wani tahsil. The total potential ofground water resources augmented through artificialrecharge is estimated in the district is 951.61 MCM.The tahsilwise details of estimated sub surfacestorage potential of phreatic aquifers throughartificial recharge to ground water are given Table4.

8. GROUND WATER AVAILABILITY VIS AVIS AUGMENTATION POTENTIAL

The ground water resources of the districtare 1278.34 MCM and possibility of further groundwater augmentation is 951.61 MCM or the actualnon-commuted surplus runoff. Thus, the overallground water resources can be made available is2230 MCM (Table 4) depending up on the availablesurplus water. However, there are variations in thetahsilwise scenario of ground water availability andaugmentation potential.

RECOMMENDATIONSThe additional storage potential of the

phreatic aquifers may be harnessed appropriately

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considering the drinking water scarcity and irrigationneeds of the area. It will generate many fold benefitsto ameliorate the suffering of underprivileged regionsand economic upliftment of the local populations.The recommendations follow.1. Efforts may be made to utilise the maximumvolume of water from the available potential of951.6 MCM or the actual non-commuted surplusrunoff, which will cater the drinking needs of ruralpeople even during the 4 summer months.2. The existing rural ground water supplyschemes will be strengthened by ground wateraugmentation measures.3. Alternately, the additional irrigationpotential can be generated from 951.61 MCM tothe extent of 1,29,500 hectors considering the croprequirement of 0.65 m prevailing in the area. Boththese requirement may also be managed by suitableappropriation of the augmented resources.4. Stress on ground water withdrawals fromdeeper aquifers will be reduced which shall be usedin exigency and emergency for the future waterneeds.5. Parts of the district is affected by highfluoride concentration in ground water resourcesand therefore the utilization of water from phreaticaquifers will minimize the fluorosis in the endemicareas as deeper aquifers are discharging fluoride richground waters.6. Appropriate recharge schemes best suitedin the area may be identified on the basis of localand site-specific surveys and terrain conditions.

ACKNOWLEDGEMENTSThe authors thank Shri Dinesh Prakash,

Regional Director CGWB; CR, Nagpur forproviding necessary guidelines and valuablesuggestions in carrying out the studies. Autherexpresses their sincere thanks to Shri P.K.Parchure,Sc “D” for his constructive comments valuable

suggestions and encouragement while preparing thepaper. Sincere thanks are due to S/Sh. BhushanLamsoge, Binoy Ranjan, D.N.Mandal, B.N.Warke,S.K.Bhatnagar, scientists, CGWB, CR who havecollected the valuable data from the district.

REFERENCES1. Census of India (2001): District census,Yavatmal (Un published).2. CGWB (2006): Report on Groundwatermanagement studies in parts of Yavatmal district,Maharashtra. Un published Central Ground WaterBoard, Ministry of Water Resources, Governmentof India report for A.A.P.; 2005-06.3. Deshmukh A.B. (1994): Ground waterresources and development potential of Yavatmaldistrict, Maharashtra. Central Ground Water Board,Ministry of Water Resources, Government of India,report no 629/DIS. p. 62.4. GSDA and CGWB (2005): Dynamicground water resources of Maharashtra as on March2004. Groundwater Surveys and DevelopmentAgency, Govt of Maharashtra and Central GroundWater Board, Ministry of Water Resources,Government of India, p.332.5. GSI (2001): District resource map ofYavatmal district, Maharashtra. Geological Surveyof India.6. Maharashtra State Gazetteers (1974):Gazetteers of India, Maharashtra state, Yeotmaldistrict, Second Edition (Revised), p. 872.7. Socio Economic Review and DistrictStatistical Abstract (2003-04): Yavatmal District,Maharashtra.Subramanian P.R. (1998): Ground water explorationin Maharashtra State and Union Territory of Dadraand Nagar Haveli. Central Ground Water Board,Ministry of Water Resources, Government of India.p. 294.

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Fig. 1

Fig. 2

95

96

Table 1: L

ithology of shallow aquifers based on the results of exploratory drilling in Y

avatmal district

contd....

Tabl

e 1:

Lit

holo

gy o

f sha

llow

aqu

ifer

s bas

ed o

n th

e re

sult

s of e

xplo

rato

ry d

rilli

ng in

Yav

atm

al d

istr

ict

TS=

Top

e So

il,

C=

Cla

y, V

B=

Ves

icul

ar B

asal

t, W

VB

= W

eath

ered

Ves

icul

ar B

asal

t, F

VB

= F

ract

ured

Ves

icul

ar B

asal

t,W

FV

B=

Wea

ther

ed F

ract

ured

Ves

icul

ar B

asal

t, M

B=

Mas

sive

Bas

alt,

WM

B=

Wea

ther

ed M

assi

ve B

asal

t,F

MB

=F

ract

ured

Mas

sive

Bas

alt,

WF

MB

= W

eath

ered

Fra

ctur

ed M

assi

ve B

asal

t, S

S=Sa

ndst

one,

SH

S= S

hale

&Sa

ndst

one

97

98

Table 2: G

round water resources of the district as on M

arch 2005 (After G

EC

-97)

Tabl

e 3:

Sum

mar

ized

res

ults

of t

he li

thol

ogy,

dep

th to

wat

er le

vel o

f the

phr

eati

c aq

uife

rs in

the

area

99

100

Table 4: Estim

ated sub surface storage potential of phreatic aquifer throughA

rtificial Recharge to ground w

ater in Yavatm

al district, Maharashtra (P

ost monsoon season 2005).


INTRODUCTION Bt cotton is available in India only in the form

of hirsutum hybrids and now occupying an area of33% to the total area of cotton while in Maharashtrait is about 80% area in Bt cotton. Production in therainfed land is a very difficult task due to uncertaintyand uneven distribution of rainfall. Hybrid cotton isa long duration crop requires more water andnutrients as compared to soybean or sorghum. It alsohas capacity to tolerant excess water conditions for4-5 days or dry conditions for 20 to 25 days. Higherproduction of cotton can be achieved at assuredrainfall of 650 to 700 mm with proper distributionof rainfall during growing season. Rain waterharvesting through tanks, ponds and reservoirs,though an age old practice but use of harvested rainwater for supplementary irrigation in the stress

16. Appropriate Technique of Rainwater Management to Enhance SoilMoisture and Higher Productivity of Rainfed Bt Cotton

*Jagvir Singh *D. Blaise *M.R.K. Rao *B. M. Khadi *N.R. Tandulkar

*Central Institute for Cotton Research, Nagpur – 440 010

ABSTRACTIn Central part of India, 70 % of arable land is rainfed without assured irrigation and

cotton occupy major area of 60 lakh ha under rainfed in 2005. Rainfed cotton productionper unit ha is very low as compared to irrigated cotton. Higher production can be achievedif soil moisture conservation technique is to be adopted during growing season of Bt cotton.Sowing of Bt and non Bt cotton hybrids was done on flat system. Two different landconfiguration systems viz. ridges and furrow and flat bed system were compared in rainfedBt hybrids at different fertilizer levels in Vertisols. Significant higher yield of seed cottonwas received by adopting ridges and furrow method over flat bed system. An additionalyield of 550 to 600 Kg/ha was obtained by utilizing run-off rain water in cotton field.Biomass accumulation and number of bolls in Bt hybrids by moisture conservation techniquewas higher compared to flat bed system in medium deep soil. The technique of soil moistureconservation through ridges and furrow was found superior over flat bed system in terms ofincreasing in moisture content by 4-5% and NUE during peak boll development stage whenrainfall is scanty. Foliar application of Zn and B (@ 0.5%) improved fibre quality of Bthybrids marginally. Higher dose of fertilizer was found non significant. Higher yield wasobserved in medium spacing (90x45cm) as compared to recommended spacing (90x60cm)adopted in medium deep soils.

period as increase productivity of rainfed agro eco-regions (Venkateswarlu, 1981). Inspite of waterharvesting on watershed, an appropriate techniqueto conserve soil moisture through management ofrun-off water during scanty rainfall and activegrowth period of cotton has been successfullydeveloped for conventional hybrids at CICR,Nagpur. The efforts have been made formaximization of transgenic Bt cotton productionthrough run-off water management during scantyrainfall under rainfed conditions.

MATERIAL AND METHODSField trials on Bt cotton was laid out at Central

Institute for Cotton Research, farm, Nagpur during2001-06, to achieve higher production through run-off water management by making a ridges and

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furrows when rainfall recedes during Septembermonth. Two field trials on Mahyco Bt cotton viz.MECH 184, 162 & 12 with different fertilizers levels75, 100 & 125% RDF and different spacing(90x60cm, 90x45cm in medium deep soil and90x60cm & 60x60cm in shallow soil) wereevaluated for two years during 2001-03. Second fieldexperiment on bunny Bts viz. NCS 913 and NCS138 with non Bt bunny was conducted in mediumdeep soil with different fertilizers levels coupledwith flat bed and ridges & furrows systems. Sowingof cotton was done in the last week of June on flatbed system. Fertilizer dose of NPK 90:45:45(F1),100:60:80(F2) and 150: 80:100 (F3) to all hybridswere given as per recommended practices. Only onespray of sucking pests was given to all hybrids and2 sprays of insecticides for controlling bollwormswere given in non Bt only. Cotton was picked thricein Bt and twice in non-Bt. Rainfall distribution andtemperature data during the crop season from 25June to 31 December is presented in table 1.

RESULTS AND DISSCUTIONEffect of rainfall distribution on growth ofcotton :

Rainfall data for the year 2002 and 2005 wasinterpreted in the paper where soil moisture contentof surface soil was measured at 80, 95 and 110 daysafter sowing (DAS). Total rainfall during the cropseason was 1018, 651 and 1012 mm in 2003, 2004and 2005, respectively. In 2002, there was a gooddistribution (32 rainy days) of rainfall of 661 mmduring active growth period upto first fortnight ofSeptember and there after very few amount ofrainfall was received. Ridges and furrows ware madeon third September, 2002 which has saved run-offrain-water of first week of September. After secondweek of September there was a scanty rainfall of 30mm. In 2005, precipitation during the active growthperiod of cotton i.e. from 25 June to 15 August was673 mm and for the period from 16 August to 30September, it was 370 mm. Rainfall distribution wasuneven at initial growth period of cotton. Ridgesand furrows were made across the slope on 22August, 2005 when rainfall recedes. In the firstfortnight of September, there was heavy rainfall of280 mm resulting in large proportion of run-offwater. If ridges and furrows made before the rainfallof September it could have been better to save run-

off water and enhance soil moisture. Thus run-offwater was saved by above mentioned technique. Itenhanced the soil moisture and nutrient utilizationin cotton. Rainfall of 80 mm received in the middleof October had beneficial effects in conservation ofsoil moisture through ridges and furrows system.

Soil conditions effect on yield and yieldattributing characters :

Biomass accumulation at maturity stage (110DAS) in Bt cotton was significantly lower thanconventional hybrids. Higher Harvest index (%) wasobserved in Bt cotton because Bt cotton had higherbolls as compared to leaves. Higher seed cotton yieldand number of bolls in Bt was recorded in mediumdeep soil as compared to shallow soil. No yielddifference was observed in shallow soil by applyinghigher dose of fertilizer (125% RDF) while inmedium deep soil, higher dose of fertilizer gavehigher yield as compared to RDF but no significantincrease in yield was recorded due to higher dose offertilizer. Hence, the recommended dose of fertilizerto hybrid cotton Bt or conventional hybrid wassufficient for getting optimum seed cotton yield.Fibre quality of Bt cotton was also improved whenBt was grown in medium deep soils.

Spacing effect on yield and conservation of soilmoisture :

In shallow soils medium spacing (90x45 cmor 60x60 cm) for hybrid cotton was found superiorover higher spacing viz. 90x60 cm or 90x75 cm.sowing of cotton rows across the slope was also agood to protect soil erosion and run-off rainwater.At maturity stage there was higher soil moisture by3-4% in lower spacing as compared to higherspacing in shallow soils resulted in higher nutrientutilization by cotton and higher seed cotton yield.In spacing trial with Bt hybrids viz. NCS 138 andNCS 913, data indicated that higher seed cotton yieldof 25q/ha in Bt cotton was obtained at mediumspacing (90cm x 45cm) as compared to 21q/ha inlower spacing (90cm x 30cm) and 22.5q/ha inrecommended spacing (90cm x 60cm), it might bedue to protection of soil erosion and run-off rainwater. Additional yield in medium spacing systemmay also be attributed by more plant population perunit area.

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Effect of soil moisture conservation technique:Significant higher yield of seed cotton was

obtained at ridges & furrows system over flat bedsystem. Both the Bt hybrids gave an additional yieldof about 600 kg by utilizing run-off water throughland configuration as ridges & furrows system overflat bed system. Higher seed cotton was recorded inboth the Bt hybrids as compared to non-Bt Bunny.No significant difference in yield was observed dueto higher dose of fertilizers. However, the increasein yield by 20-25% at ridges and furrows systemwas noticed at higher dose of fertilizer.

CONCLUSION Therefore, to make this technique a viable and

successful one in rainfed Agro-ecoregions, ridgesand furrows are to be made across the slope andwhen rainfall recedes and demand of water is morefor development of bolls in cotton. The maximumconservation of run-off of scanty rainwater and itsprudent utilization practice is worth formaximization of cotton production under rainfedcondition.

REFERENCE :Venkateshwarlu J. (1981). Maximization of cropproduction in dry lands. J. Soil Cons. 9: 124-40.

Table-2 : Effect of fertilizer levels at different run-off water managementon Seed cotton yield (q/ha)

Hybrids Seed cotton yield F1:90:45:45 F2-100:60:80

Flat Bed Ridge & Flat Bed Ridge & Flat Bed Ridge &furrows furrows furrows

Bt NCS 138 17.28 22.06 15.95 21.62 16.6 23.31

Bt NCS 913 15.99 21.72 15.91 20.55 16.06 20.88

Non Bt (Bunny) 9.34 12.06 9.03 12.08 9.65 12

Table 1 : Rainfall (mm) distribution pattern during crop season

Period Rainfall No. of rainy days Max Temp. (Mean)Year-2002

25 Jun to 15 Sept 661 32 330 C(Jun-3, Jul-3, Aug-19, Sept-7) (June- 36, Jul -34, Aug- 30, Sept- 32)

16 Sept to 30 Sept 7 2 320 C

1 Oct to 15 Oct 13 1 340C

Year-2005

25 Jun to 15 Sept 437 33 340C(Jun-38, Jul-30, Aug-31,Sept-31)

16 Sept to 30 Sept 315 16 320C

1 Oct to 15 Oct - - 320C

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Table -3 Surface soil moisture content of different DAS in 2002

Growth Shallow soil Medium soilperiod Flat bed Ridg.& Furr. Flat bed Ridg.& Furr.At 100% RDF treatment80 DAS 20 24.5 22 2795 DAS 16 20 20 24.5110 DAS 10.5 12.5 11 13.5 At 125% RDF80 DAS 20 24 22 2695 DAS 15 18.5 19.5 24110 DAS 9.5 12 10.5 11.5

Ridg.& furr.-Ridges & Furrows

2 6 . 5 2

2 4 .6 9 2 4 .3 2 4 . 4 2

2 1. 8 6

2 0 . 8

2 4 . 9 4

2 1.9 62 2 . 8 8

2 1.5 2

12 .4 3

14 . 0 814 .9 6

13 .9 5 13 . 7 1

0

5

10

15

20

25

30

90x30 90x45 90x60 100:60:80 150:80:100

Spacing x Fertilizer

Seed

cot

ton

yiel

d (q

/ha)

NCS 138 NCS 913 Bunny non-Bt

Fig 2: Effect of Spacing and Fertilizers on Bt cotton yield

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Introduction :Rainwater harvesting (RWH) refers to

collection of rain falling on earth surfaces forbeneficial uses before it drains away as run-off. Theconcept of RWH has a long history. Evidencesindicate domestic RWH having been used in theMiddle East for about 3000 years and in other partsof Asia for at least 2000 years. Collection andstorages of rainwater in earthen tanks for domesticand agricultural uses is very common in India sincehistorical times. The traditional knowledge andpractice of RWH has largely been abandoned inmany parts of India after the implementation of damand irrigation projects However, since the early 90s,there has been a renewed interest in RWH projectsin India and elsewhere. Rainwater harvesting canbe done at individual household level and atcommunity level in both urban as well as rural areas.At household level, harvesting can be done throughroof catchments, and at community level throughground catchments. Depending on the quantity,location and the intended use, harvested rainwater,it can be utilized immediately or after storage. Otherthan as a water supply, RWH can be practiced withthe objectives of flood control and soil erosioncontrol. The total water resources, comprisingsurface water (1953 bcm) and ground water (423bcm) are not uniformly distributed, in the sense,roughly 67 percent of the resources are reported tobe available in the Indo-Gangetic alluvial basinscovering 33 percent of the geographical area of thecountry as against 33 percent of the potential in thehard rock regions occupying 67 per cent of thegeographical area.

Components of RWH System :A RWH system has three componentsThe catchments;

The collection system; andThe utilization system.

Factors : The following factors are to be taken intoconsideration for RWH practices

Location and topography of the area – Whetherplane or hilly area, rain fed, desert, steep slope,drought prone, flood prone, rural and urban area.

Rain fall pattern – Whether rain fall isdistributed uniformly through out the year orintermittent.

Intensity of rain fall- It varies from 100mm inwestern Rajsthan to 11,000 mm in Cherapunji(Meghalaya).

Soil Characteristics- Whether the soil ispermeable or impermeable to facilitate recharge ofaquifers.

Catchments area – Whether barren land, Forestarea, Agricultural land, Ice caps and desert area.

Water Resources at a Glance (India) : Out of100% water what we have.

97% as sea water, such a huge water source isof no use to us unless we treat it with highlyexpensive methods like Reverse osmosis orevaporation etc… However water which we get bysuch techniques is not affordable by everyindividual.

2% water is in the form of ice and glaciers andis also not of any immediate use to us.

1% water is in the form of rivers, lakes, groundwater etc. Which is the only source, readily availableto whole world to satisfy their needs.

This is represented in Fig-1. Now lets narrowdown our focus to our country. Out of 1% availablepotable water source globally, only 4% is availablein India. As compared to the world population, 17%population live in India. Because of this situation there


17. Rain Water Harvesting – An ultimate need in 21st Century

Er. L. K.Bisoyi

*FIE (India), ME (PH) (Committee Member, Env. Engg. divisionI.E (India), Orisssa state centre Bhubaneswar)Address : Plot no-759, Jayadev Vihar, Bhubaneswar (Orissa)

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is a tremendous crisis on our Water demand and supply arrangements.

Water resources

Available water in BCM Losses in BCM Unutilized water that can be harnessed in BCM

From all natural – Evaporation – 700 Remaining available water ………………1100Sources — 4000 Flow on ground – 700 Out of which

Flow to sea – 1500 Ground water recharge – 430Present utilizable surface water – 370Unutilized water that can be harness – 300

Year 1950 2000 2050 (prob.) —Availability of land – ha/capita 0.28 0.1 0.07 —Year 1947 1998 2005 2025 (prob.)Availability water in Cum/yr. capita 6 2.2 1.6 0.5

Per - capita availability of land/water in India :

Projected water consumption :In BCM

Irrigation Domestic Manufacturing Power Total

1997-98 560 30 30 9 6292020 BAU 640 56 57 28 7812020 BCS 602 51 57 27 737(Source – Water resources division, planning commission Govt. of India)

Potential of Water Harvesting to meet India’s Drinking Water Needs

Assumptions

Population: 1050 millionAverage annual rainfall: 1,100mmLand area for which land-use records are available: 304 million hectaresAverage household water requirement nationwide: 100 litres/day/person

Annual water Water collection efficiency Land requirement % of India’s landrequirements (% of rainfall collected)

38,325 billion litres 100% 3.50 million hectares 1.15%38,325 billion litres 50% 7.00 million hectares 2.30%

Harvesting potential(India) :

Issues : A number of issues may affect the widespread adoption of RWH systems in India. Such as:Economics and Technology – Research and design needs to improve the cost-effectiveness of RWH, like:

Economically optimizing the size of system componentsMinimizing the quantity or quality of materials needed to create any given volume of water storage.Developing new designs for tanks, guttering and catchmentsDeveloping measuring instruments to assist RWH system managementEstablishing the environmental and economic benefits of reducing extraction of domestic water from

distant point sources.Water Quality and Health : the impact of RWH on health such as :

The likely causes of low RW quality (physical, chemical, biological) and assessing its impact on health

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Actual RW quality as a function of userbehaviors, system design and environmentalconditions

Devising new techniques for reducing turbidityand pathogens, and improving the taste

Understanding the links between RWH and theprevalence of disease vectors like mosquitoes andidentifying cost-effective and sustainable vectorcontrol measures.Water Policies, Regulations and Attitudes thataffect taking-up of RWH projects on wider scales,including:

Current policies, priorities, rules and concernsof key stakeholders

RWH popularization and disseminationtechniques.

The optimal role of RWH alongside other watersupplies in different regions of the country.

Challenges / Strategies in 21st Century –Challenges and Strategies for water in 21st

century are as given below.Challenges

Ground water depletionWater quality deteriorationLow water use efficiencyExpensive new water sourcesResource degradationWater and healthMassive subsidies and distorted incentivesDevelopment of new water sources

StrategiesRainwater harvestingComprehensive water policy reform and

demand managementSecure water rightsUser management of irrigation systems.Reformed price incentivesAppropriate technologyEnvironment protectionTradable water rightsInternational co-operation

Need and Advantages of RWH : The need andadvantages of RWH are as enumerated below

Choice between Storage and ArtificialRecharge of Rain Water (Fig. 2, 3 & 4) Thedecision whether to store or recharge water dependson the rainfall pattern of a particular region. Forexample, in places like Kerala and Mizoram, rainfalls throughout the year, barring a few dry periods.In such places, one can depend on a small domestic-sized water tank for storing rainwater, since theperiod between two spells of rain is short. On theother hand, in dry areas like Delhi, Rajasthan andGujarat, the total annual rainfall occurs only during 3to 4 months of monsoon. The water collected duringthe monsoon has to be stored throughout the year;which means that huge volumes of storagecontainers would have to be provided. In Delhi, it is

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more feasible to use rainwater to recharge groundwater aquifers than for storage.

Rainwater Harvesting Practices(Fig.5-10) :There are two main practices of rainwater

harvesting:Storage rainwater on surface for future use. It

is a traditional practice and structures used are underground tanks, ponds, check dams, weirs etc.

Recharges of ground water: is a new conceptsof rain water harvesting and the structures generallyused are:

Pits – recharge pits are constructed forrecharging the shallow aquifers.

Trenches – These are constructed when thepermeable strata is available at shallow depths.

Dug wells – drainpipes to a filtration tank, fromwhich it flows in to the dug well, divert rainwater

that is collected on the rooftop of the buildingHand pumps – The existing hand pump may

be used for recharging the shallow / deep aquifers,if the availability of water is limited.

Recharge wells – recharges wells are generallyconstructed for recharging the deeper aquifer andwater is passed through filter media to avoid chokingof recharge wells.

Recharge shafts – for recharging the shallowaquifers, which are, located below clayey surface.

Lateral shafts with bore wellsfor rechargingthe upper as well as lengths. Deeper aquifers lateralshafts of 1.5 to 2-mt width and 10 to 30mt.

Spreading techniques- when permeable stratastart from top then this technique is used. Water isspread in streams/nalas by making check dams,cement plugs, gabion structures or a percolationpond may be constructed.

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Is there Water Shortage ?Every village in India can meet its own water needs: Land area needed per village in different states of

India to capture enough rainwater to meet drinking and cooking water needs

Note : Calculation based on the assumption that average village population in different meteorologicalsub-divisions is the same as that of the state.Source : India Meterological Department for normal rainfall data and based on Census of India data for1981, 1991 & 2001

International Initiatives :In U.S. RWH practice in individual and small groups of Texas University through 3 cascade ponds to

support aquatic life for biology laboratory fed by harvested rain water.In Mexico due to artificial recharge of aquifer 50% reduction cost of pumping of ground water achieved.In South Africa in 25 million hector one non-native weed consumed almost 7% more of country’s run

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off and it was replaced by indigenous plants to savewater remarkably.

With active participation of NGO’s, World Bankand Denmark Govt. a special type of grass plantedin Denmark in slopes which reduced 70% rainwaterrun off and even strong roots of these grasspenetrated hard rock and improved infiltration.

Major initiatives(India) :Recommending schemes which will ensure

availability of minimum 25 kiloliters of water per yearfor each citizen in the country.

Water harvesting must be made mandatory forthe buildings. Necessary legal provisions may bemade in this regard.

Appropriate legal provisions for makingrecycling of water mandatory in all buildingsparticularly larger hotels and industries where largeamount of water is consumed are to be taken out.

Since sustainability of the drinking watersource is of paramount importance for smoothfunctioning of rural water supply, 25 per cent out of20 per cent of the allocation under Accelerated RuralWater Supply Programme (ARWSP) has beenearmarked exclusively for water harvesting schemesto make implementation of such schemes mandatory.

Similarly, 25 percent out of the allocation underPrime Minister’s Gramodaya Yojana has also beenearmarked for funding schemes under submissionon sustainability.

MP’s are to be requested to utilize Local AreaDevelopment Fund in their respective constituenciesto take up water harvesting scheme.

Besides feasibility studies alone withconsultancy services for preparation of pilot projectson rainwater harvestings in select states have alreadybeen taken.

Further, preparation of user friendly atlas typeof document on traditional water harvestingstructures in various parts of the country has beeninitiated for popularizing the concept of waterharvesting amongst all concerned including thecommunity.

Conclusion : Rain harvesting is emerging as a viablelong term strategy to tackle the increase pressure onfresh water resources of our country. In addition towater harvesting, water recycling is essential forlarge consumers such as hotels, public Institutions

and industries. The recycled water must be used forall usages including agricultural needs, except fordrinking. This will reduce the per capital requirementof water to nearly 25% of the present consumptionand enable larger number of population to getadequate potable water and for sanitation.Community managed in situ water harvestinginterventions on watershed basis can better thequality of life of people be ensuring access to safedrinking water and increased productivity of naturalresources. Unless some crucial measures are nottaken in time then by 2025 India will be highly waterstressed.. In view of this Rain water-harvestingsystem is the only alternative, which can providegood quality of water. Harvested rainwater ifrecharged in to the ground then problem of depletionof under ground water can be sorted out very easily.It has become very necessary to form certainregulations and laws for the effective utilization ofavailable water source as well rain water harvestingsystems implementations so that our coming futurewill be secured at least on Water front. Financialincentives also can be devised to over come theconstraints.

Selected Reading• Agarawal, A etall – State Indias environment – Centrefor science and Environment New Delhi. 2001 edition• Agarawal, A etall – Making water every body business– Practice and policy or water harvesting - do -• Bisoyi L.K. – Rain water harvesting and Artificialrecharge – An innovative approach for crisis managementand sustainable development – An experiences of NewDelhi- 21st National convention of Env. Engineers, 11-12Nov. 2005, Bhubaneswar, Orissa.• Concepts and practices for rain water harvesting –CPCB-MOEF-10/2001, New Delhi.• Kalam A.P.J- Integrated water mission - do –• Kulkarni M.K. – Rain water harvesting – Definite toolto win over water scarcity – Integrated water and wastewater management for sustainable urban development –Modern trends I.E(India), Pune Local Centre – 10-11March-06.• Nimbal F. – Rain water harvesting – Yojana – 6/05New Delhi• Rain water harvesting – Need of the Millennium-I.E.(India), Tamil Nadu State Center. Jointly with HUDCOand Anna University- 12/2000.• Sahoo. N. – Water harvesting in water sheds. – VigyanDiganta – 12/05, Bhubaneswar.• Yadupatty M.R. etall- Rain water harvesting – A casestudy of in a College campus at Myosore – Hydrologyjournal, quarterly – IAH – ISSN-0971-569X-vol-28- no-3-4 Sept.2005.

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18. Traditional Rainwater Harvesting Systems – Our Field Experiences

DHAN Foundation

18, Pillaiyar Koil Street, S.S.Colony, Madurai – 625010, Tamilnadu

turns into flood inundating vast tracts of land anddamages life and property. When the rainfall isscanty, part of it gets lost by interception by treecanopy, evaporation and run off leaving very littleof it for storage and future use. Although water isrenewable, it is a finite commodity. Thereforerainwater harvesting and storage becomesimperative in either case, for effective use by people,livestock and nature.

While in the urban areas rainwater harvestingis practiced for drinking, domestic, gardening, andground water recharge purposes, in rural areas it isundertaken more extensively for irrigation, drylandagriculture, horticulture, ground water recharge,domestic, livestock, inland fisheries, duck rearingand for multifarious other similar purposes. Eachform of storage has its specific merits and uses,although from the efficiency point of view,underground storage is the best as evaporation andother losses are eliminated.

SYNOPSISTraditional rainwater harvesting systems comprise mainly tanks, ponds and Ooranis

(drinking water ponds). Considering the erratic rainfall obtaining in our country, they havebeen constructed by our ancestors over the past centuries, to capture the monsoon rainsand store them for later use when required. During the past few decades they are gettingdegraded and even extinct due to various reasons, which has resulted in alarming waterscarcity, over exploitation of ground water and environmental hazards. DHAN Foundation’sstudy, approach and efforts made to renovate these small scale water bodies with communityparticipation are described. The achievements and experiences of these efforts are explained,with particular reference to the role of these renovated water bodies in augmenting storagecapacity, stabilizing tankfed & rainfed agriculture, increasing crop production and mostimportantly improving the groundwater potential through recharge. In conclusion,formulation of a massive programme of tank renovation & its implementation with somepriority criteria, and only through the user groups is recommended.

INTRODUCTIONRainwater harvesting is undertaken mainly to

capture the run off from the seasonal rains and storeit for use in times of need. The storage is made onthe ground surface or underground, depending uponthe topography of the land, the types of surface andsub surface soils and the underground geologicalformations. Storage cisterns, check dams, farmponds, percolation ponds, Ooranis (drinking waterponds), irrigation tanks and reservoirs comprise thesurface storage systems, Rain water stored in thesoil profile upto its field capacity, sub surface damsconstructed in deep sandy beds across rivers andstreams, sumps, dug wells, filter point wells, tubewells and aquifers constitute the undergroundstorage systems. The source of supply for all thesestorages is the rainfall which is highly variable.

The rainwater which is not harvested andstored, mostly runs off the land surface and getswasted without proper use. Where the rains areintense and continuous over some days, the run off


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Table 1 : Merits, demerits & uses of different forms of rainwater harvesting and storage

DHAN FOUNDATION’S APPROACH TORAINWATER HARVESTING IN RURALAREAS

DHAN Foundation is a grassroots developmentorganisation working mainly in rural areas with afocus on water resources development and their localmanagement. More specifically, it has beenconcentrating on the restoration of small scale waterresources like minor irrigation tanks and watersheddevelopment, and the revival of local initiatives likethe maintenance and management of the water

resources as a means to increase productivity of tankfed and rainfed agriculture. These rainwaterharvesting structures of one form or the other, benefitpredominantly the large number of livestock, smalland marginal farmers and the rural folk who haveno access to large and medium reservoirs. Theorganisation comprises highly motivated, wellqualified and/or experienced professionals, who livein and work from the villages, with a deep concernfor poverty alleviation through developmentalactivities, and build people to become self reliant.

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STUDYIn order to gain a good understanding of the

traditional rainwater harvesting systems like tanksand ponds DHAN Foundation first took up detailedstudy of the location, design and constructionfeatures, the water management practices and themaintenance of the systems. It found that those rainwater harvesting structures were ideally located,ingenious but simple in design, constructed withlocally available materials and maintained by thelocal communities. However due to various reasons,the foremost among them being the decline ofcommunity management, these rainwater harvestingstructures have been steadily getting dilapidated andin some cases even extinct. The government takingcontrol of the water bodies during the colonial rulehas triggered the decline of community managementof them. Massive groundwater programmes like theconstruction of dug wells and tube wells,aggressively promoted by government organisationsand banking institutions with inducements in theform of liberal loans and subsidies, technologicalinnovations like electrical pumpsets, provision ofsubsidised and in many cases free supply ofelectricity to agriculturists for lifting water from thewells - all these had contributed to the neglect ofthe tanks.

This neglect has set in motion, other intrusionslike encroachments, weed infestation andsedimentation of feeder channels and tank beds,erosion of earthen embankments of tanks, loss ofsluice shutters, leaky sluices and damaged surplusweirs, all of which have further compounded thedegradation process of the water bodies. Instead ofrepairing or restoring the water resources throughcommunity action, the people began looking uptothe government to undertake the works. Thegovernment’s attention was focussed more onconstruction of massive dams and large scaleirrigation facilities across the country, terming themas the new temples of modern India. It perhaps feltthat these small scale water bodies are too small toprovide any spectacular benefit and too scattered tohave an effective impact on the people, to initiateany activity for their restoration. For a country whichat the time of independence was in a hurry to catchup with the rest of the world and where millions ofpeople had to be literally hauled up above the povertyline, this was considered to be the way out. But

successive governments failed or did not careenough to study and revive the old methods of waterharvesting, which would have once again made therural communities self reliant with regard toirrigation and drinking water. Inspite of the largenumber of large and small dams constructed acrossmany rivers in the country, irrigation facilities arestill woefully inadequate and people continue todepend upon erratic rainfall conditions. In a countrywhere many regions are arid, semi arid or prone tomonsoon floods, this dependence has proved costly.Where the rainfall is unseasonal, in excess orinadequate, the price paid is heavy in terms ofdestroyed crops, mounting debts and uprootedhuman lives. The most cost effective way by whichthe water resources can hence forth be developed,at least in Tamilnadu and the adjacent peninsularstates, is by rehabilitating the thousands oftraditional irrigation tanks which are centuries oldand which are still functioning well where the localcommunity is cohesive and enlightened, instead ofinvesting in new structures and systems. Furtherthere are no more hydrologically appropriate sitesavailable for forming new tank systems. After thedetailed study and analysis of the reasons for thedecline of the small scale water resources, DHANFoundation has ventured to restore these tanks totheir original design standard and performanceefficiency; and more importantly, to undertake theprogramme by organising the concerned people,enlisting their active participation, building theircapacity and making them contribute a part of thecost of restoration and thus become stakeholders andthen facilitating them to implement the rehabilitationworks. These processes would ensure proper timelymaintenance and management of the water resourcesand make them sustainable over the years, so thatthe future generations would continue to enjoy thebenefits derived. History confirms that a communityis the best protector of its own resources.

ACHIEVEMENTSDuring the past thirteen years DHAN

Foundation has undertaken rehabilitation works ofmore than 750 minor irrigation tanks and Ooraniswith people’s participation, in the five districts ofMadurai, Ramanathapuram, Theni, Tiruvallur andKancheepuram in Tamil Nadu; in two districts ofChittoor and Nalgonda in Andhra Pradesh and in

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Tumkur district of Karnataka. Besides, it has alsoundertaken sixty tankbased watershed developmentworks with people’s participation and contributionin Madurai, Ramanathapuram, Virudhunagar,Tuticorin and Chittoor districts. Twenty fivecommunity wells were also constructed in Madurai,Ramanathapuram and Tiruvallur districts. The fundsto carry out these works came mainly from theDistrict Rural Development Agencies (DRDA),Drought Prone Area Programme (DPAP), NationalBank for Agriculture and Rural Development(NABARD) and Sir Ratan Tata Trust (SRTT) whilethe International funding agencies like the FordFoundation and NOVIB, met the overhead chargesof DHAN Foundation. While the funding agenciescame forward with 100 percent of the cost of worksas grant, DHAN Foundation availed only 75 percentof the works cost, and successfully mobilised theremaining 25 percent from the beneficiaries, rightfrom the initiation of this programme in early 1992.We are happy to find that since 1997, the governmentalso has changed their financing policy from 100percent grant to 75 percent and insists on 25 percentpeople’s contribution and full participation in manyof their development programmes.

DHAN Foundation organised about 950 waterusers (WUAs) and watershed developmentassociations with 60,000 members in order to enablethem to carry out the development works mentionedabove and to manage them thereafter. It alsoorganised tank farmers’ federations at the PanchayatUnion and district levels to guide and assist theWUAs in their work, ensure the quality of work,mobilise funds towards people’s contribution andliaise with funding agencies for speedy disbursementof funds. While the members of the general bodiesof the various associations were the actual waterusers, in the selection of office bearers of theExecutive Councils of these associations DHANFoundation focussed their attention and assisted themembers to make the right choice with great care. Itwas these people’s organisation which did theplanning, implementation, quality control andsystematic accounting of the works, DHANFoundation providing only the required technicaland managerial support to them. DHAN also heldseveral discussions at the tank and village levels tomotivate the people and organise them, assisted themin drafting byelaws and registering the associations

and federations to provide credibility to them. DHANorganised several exposure visits to the people toother areas where the tank rehabilitation works wereundertaken, for them to see and share the experienceof their counterparts in those areas. Several trainingprogrammes were conducted to the members of theAssociations, Executive Councils and Federations,on leadership, organising people, constructiontechnology, improved water management and cropproduction techniques, accounting procedures andthe like, to build their capacity, motivation andconfidence. All these efforts paid dividends toDHAN workers who could build a good rapport withthe villagers and instill confidence in them. Duringthe initial years, with DHAN workers living in thevillages and the nearest small towns, it took aboutsix to nine months to form one association. Presentilywith the experience gained over the years it takesonly a month or two to do this. The process adoptedto form WUAs has also been refined and improvedso that the farmers’ federations themselves organizenew WUAs and undertake the activities that DHANhas been carrying out, in order to upscale theprogramme in a big way in the future. It is this effortthat makes people committed to their roles andresponsibilities which we believe would result insustained community management of the waterresources.

EXPERIENCESDHAN Foundation itself gained considerable

experience in these thirteen years of its involvementin small scale water resources development. In itspilot (first) phase of three years, the focus of workwas on rehabilitation of tank irrigation systems,wherein the emphasis was on restoring the tankstructures like tank storage capacity, bunds, sluiceoutlets, and surplus weirs to their original designstandard. This effort has resulted in greateracquisition and increased storage of rain water overlonger periods. Additional storage capacity rangedfrom 100 to 200 percent. In the second phase of threeyears, the emphasis was on regeneration of farmers’management in addition to rehabilitation. This effortresulted in communities’ participation with activeinvolvement, reduced wastage and equitabledistribution of water among the users. This was madepossible by the users regulating the water usethrough their local management. During the third

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phase, tankfed agriculture was the focus besiderehabilitation and farmers’ management. This effortresulted in provision of appropriate inputs at the righttime, improved water management and increasedcrop production ranging from 30 to 100%. And inthe fourth phase sustainability of the rehabilitatedtank systems in given importance by organisingMicro Finance Groups & facilitating them toperiodically maintain and manage those traditionalsmall scale water resources. This has resulted ingreater cohesion among the user groups and theirconcern to maintain and manage the tank systemswith their own initiative and ensure the sustainabilityand thus become self reliant.

Similarly, from taking up isolated tanks forrenovation, the planning and implementation wasmade taking a cascade of tanks as a unit, so as tocapture and store the entire run off flowing downthe micro watershed. The feeder channel cleaningand restructuring (removal of wild growth ofvegetation and desilting) and removal ofencroachments formed an important component oftank rehabilitation. This work was found to be themost cost effective component for augmenting tankstorage, next to provision of plug and rod shuttersto sluice outlets for preventing leakage andconserving the harvested rain water. The philosophyhas been “a drop saved is equal to a drop added tostorage”. Another component of work added to tankrenovation was the provision of silt traps on the frontside of sluice opening to prevent the choking up thevent way (pipe or barrel). Tree planting on theforeshore of tank bed in the belt of land bound bythe FTL contour of the tank upto the governmentboundary has been introduced, to provide additionalincome to the people through usufructs and tominimise silt accretion into the tank waterspread.Incidentally tree planting also serves to identify theencroachments if any and to remove them promptly.Yet another innovation made is provision of deadstorage within the tank bed to hold water in a selectedpocket to facilitate aquaculture, to serve the drinkingwater needs of livestock and/ or to provide lifeirrigation to withering crops in times of waterscarcity. The community wells sunk in the tankcomplex get much of their recharge from the tankitself and from the water applied for the crops raisedin the tank command and provide supplemental orlife irrigation to the crops after the tank gets emptied.

This has been a boon to the small and marginal landholders who could not have their own individualwells to practice conjunctive use.

All these water conservation measures areintroduced either on the initiative or with the consentof the users of the water resource and in accordancewith their priorities. When the people get involvedintensely in every activity of tank rehabilitationplanning, decision making and implementation, theytake good care to prevent wastage, preserve thestored water, and distribute it equitably amongthemselves. They maintain the structures themselveswith their own funds mobilised for the purpose. Intimes of disaster like a tank bund getting breacheddue to unprecedented rains, the people themselvesundertake breach closing and bund strengtheningwork collectively, when every able bodied villagerjoins in the team work. This attitudinal changeoccurs mainly through each member of the WUAfinding strength and confidence in unity. This is themost important and gratifying experience that hashappened.

TANKS AS RECHARGE STRUCTURESAlthough the primary use of tanks is irrigation,

they contribute as much as 40 percent of their storageto augment groundwater resources through recharge.According to a study report by the NationalGeophysical Research Institute (ICAR), Hyderabad,measurements carried out in about 20 river basinswell distributed over the various climatic andgeomorphic zones in India, 5 to 10 percent of theseasonal rainfall is contributed as annual rechargein the peninsular hard rock regions, whereas inalluvial areas, about 15 to 20 percent of the rainfallcontributes to groundwater. The Central GroundWater Board in its manual on “Groundwaterresources of India (1995)” accounted nearly 30 to40 percent of applied irrigation water as seepagereturn from irrigated fields and field channels.Irrigated fields also contribute to augmentation ofgroundwater resources. The average infiltration ratefrom paddy fields is reported to be generally higherthan that from tanks. The paddy field infiltrationratio (that is, the ratio between the water infiltratedunderground to water applied) varied between 55and 88 percent. Paddy fields can be used as groundwater recharge basins by harvesting the rainfalleffectively. Water spreading as a recharge method

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is practiced on an increasing scale all over the worldin areas where the aquifer is shallow. Our experienceof the effectiveness of rehabilitated irrigation tanks& Ooranis as groundwater recharge structures inTheni and Ramanathapuram districts is that there isa perceptible rise in the water table ranging from 4to 6 metres (m). Before restoration of the tanks, thewater table in the wells was between 30 to 45 mbelow ground level. After the desilting of the feederchannel & tank bed, the tanks filled up in the nextrains and within a few weeks the water table in 169dug wells situated close to Silamalai tank in Thenidistrict rose by 5 to 6 m. In the wells situated in thezone of influence of Kurinjiappagoundan tank inTheni district, the water table in twenty out of fiftywells rose by five metres from 40 to 35 m belowground level, while in the remaining thirty wells therise ranged from 2 to 4 metres. In the next year, thewater table rose still further, with many dried wellsgetting rejuvenated and providing adequate watersupply for irrigated crops. The area under wellirrigation in this region has expanded by 50 to 100percent and ground water became a dependablesource of supply. A new well 22 m deep excavateddownstream of a renovated tank has 9 m depth ofstorage & provides drinking water for the entirevillage of Silamalai. In most of the wells under therenovated tanks, people no more resort to deepeningof the wells, which they were doing earlier, as theyhave adequate supply.

Similarly in Ramanathapuram district after thereclamation of Ooranis, the water stored in them isavailable for drinking purposes almost round theyear as against hardly 3 to 4 months’ availabilityearlier, as the storage capacity is increased three tofour times by deepening the Ooranis. Besides, thequality of water in the surrounding wells has alsoimproved as confirmed by tests carried out in watertesting laboratory as well as by the local villagers.Above all, the womenfolk are saved from thedrudgery of fetching water from distant places andthe time spent for the purpose. Since the Ooranireclamation works also have been carried out withpeople’s contribution of 25 to 30 percent and theirparticipation, the beneficiaries take good care topreserve them from pollution and use the Ooraniwater without wastage.

OTHER BENEFITSIn quite a few tanks renovated in the rural areas

of Madurai district, inland fish culture has beenintroduced in tank water which fetches the waterusers a sizable income ranging from ten to fiftythousand rupees a year per tank, depending uponthe period of tank storage and the efforts taken bythe local people to raise fish. Usufructs from treesplanted on the tank bunds and in tank beds havegenerated additional income upto Rs 75000/- overa six year period to the water user group.

In some tanks and Ooranis desilted under thetank rehabilitation programme, the excavated tanksilt was applied to their agricultural lands, therebyimproving the texture and fertility status of the soils.

CONCLUSIONSThe Institute of Remote Sensing (IRS) Anna

University has prepared micro watershed mapsPanchayat Union wise, delineating therein therevenue village boundaries; and identifyingfavourable areas for ground water recharge usingremote sensing and GIS. We therefore suggest thatthe tanks situated in such favourable tracts may betaken up for rehabilitation on a priority basis, sothat the people of those regions will get the benefitsof tankfed agriculture and groundwater recharge aswell and also augment the storage of the existingwells in the concerned tank commands.

We also strongly recommend that a ten yearplan for the period from 2006 to 2016 be preparedto rehabilitate all the existing tanks and ooranis;initiate tankbased watershed programme in all thedistricts of Tamilnadu to include farm ponds,drainage line treatment and tree planting on amassive scale. We believe that this effort willstrengthen people’s participation and provide lastingbenefits to the rural communities through tankfedagriculture and groundwater recharge.

All existing encroachments in the water bodiesmay be summarily evicted and future encroachmentsbe strictly prohibited in order to preserve these giftsof our forefathers and can be passed on to our futuregenerations to go along Nature’s path. Here it willbe appropriate to conclude this paper with aquotation from Gandhiji. “The greatness of a nationand its moral progress can be judged by the waypeople treat the environment”.

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19. Importance of Rain Water Harvesting in Current Senario

*S. R. Asati **Abhijit Deshpande

*Lecturer-Selection Grade **LecturerDeptt. of Civil Engg., MIET, Gondia- 441 614 (M.S)

is stored in inland water bodies both natural (lakesand ponds) and man-made (tanks and reservoirs).India receives a total precipitation of 4000 cu.km offresh water in the form of rain and snowfall out ofwhich only1869 cu.km is available as annual surfacerunoff and only an estimated 1122 cu.km can beexploited due to topographic constraints anddistribution effects.

Groundwater represents one of the mostimportant water sources in India and accounts forover 400 cu.km of the annual utilizable resource inthe country. Due to the highly variable nature of theclimate, groundwater has become a popularalternative for irrigation and domestic water useacross India. Reliance on groundwater resources isparticularly strong where dry season surface waterlevels are low or where wet season flows are toodisruptive to be easily tapped. In addition to beingaccessible, groundwater quality is generallyexcellent in most areas and presents a relatively safe

Abstract In the last few decades, rapid growth in urbanization and industrialization trends,and dependence on ground water for domestic and agricultural purposes by rural communityaltogether have resulted in to exploitation of ground water without much focus on its recharge.Thus there is urgent need to search suitable methods to replenish the cause. In this contextrainwater harvesting has been the crucial factor for sustaining the fast depleting surfaceand sub surface water resources. Rainwater harvesting is the traditional technique hasbeen in use in hilly areas such as Forts and desert areas such as Rajasthan to conserve thewater in the dry periods. Ground water is the main source and being exploited since thedays of Mahabharata. The current paper focuses on the per capita water availability, criticalground water deficit problems in India and the various water harvesting techniques suitablefor the Indian conditions. Each and every belt now faces the problem of depletion of groundwater. This is the time to collect the people so as to solve the problem collectively, traditionally,economically, qualitatively so as to fulfill the minimum demand for the long time. Governmentpolicies and economic incentives have also determined how and how much of India’s watercan be used.

IntroductionThe unequal distribution of water resources

over the time and geographic area and its constantexploitation, especially the ground water resourceshas arisen the severe ground water problems mainlydue to its large dependence on ground water by therapid growth in urban, rural and industrialestablishments. This has resulted in decrease inground water levels without much focus on itsrecharge and has thus necessitated the developmentof water harvesting systems. Government policiesand economic incentives have also determined howand how much of India’s water can be used. Thefollowing discusses some of the majorcharacteristics of water in India: where it comesfrom, where it goes and how it is currently beingmanaged.

A portion of the total precipitation of the totalwater is absorbed by the soil and is stored inunderground aquifers. A much smaller percentage

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source of drinking water for Indians in rural and urbancenters.

The presence and availability of groundwatervaries greatly with changes in topography,subsurface geology and the prevailing climate in theregion. In some areas, groundwater exists in deepaquifers while in others the water is stored near thesurface. The location of the aquifer also affects itsrecharge rate and its susceptibility to pollution andoveruse.

Water Harvesting SystemsWater harvesting structures have been designed

to help capture and store rainwater during themonsoon season and serve as a source of drinkingand irrigation water during the rest of the year. InIndia, tanks, ponds and reservoirs cover a total of 5million hectares, the majority of which lies in thesouthern portion of the country (MOWR, 2001).Although they do not make a significant contributionto the total freshwater water resource in India, waterharvesting systems do have a strong impact in termsof drinking water and irrigation provision on a localscale.

Many of the water harvesting structures usedin India are based on ancient models, mainly due tothe potential of these systems to supply freshwateradequate to all areas and sectors and therefore highlyadapted to the prevailing climatic and hydrologicconditions of the area. However, since colonialtimes, these systems have been increasinglyabandoned and neglected in favor of large dam andcanal irrigation projects. So far, these ‘modern’structures have been successful in providing waterto portions of rural and urban India, yet higheconomic, social and environmental costs havereduced their overall benefit. As a result,development and civil society organizations havebeen advocating the return to local water harvestingsystems for domestic and irrigation purposes. Asawareness and public opinion continue to grow,water-harvesting systems will become increasinglymore important source of water in India.

In the past several decades, industrialproduction has increased in India owing to anincreasingly open economy and greater emphasison industrial development and international trade.Water consumption for this sector has consequentlyrisen and will continue growing at a rate of 4.2%

per year (World Bank, 1999). According to the WorldBank, demand for industrial, energy production andother uses will rise from 67 billion m3 to 228 billionDemand from the domestic sector has remained lowand accounts for only 5% of the annual freshwaterwithdrawals in India (World Resources Institute,2000). Domestic water use will increase as thepopulation continues to grow and access to water isimproved. Recent data from the World Bankindicates that demand over the next twenty yearswill double from 25 billion m3 to 52 billion m3. Only85% of the urban and 79% of the rural populationhas access to safe drinking water and fewer still haveaccess to adequate sanitation facilities (WorldResources Institute, 2000). The central governmentmade a commitment to improve access to water inrural and urban areas in the National Water Policyadopted in 1987. The original goal of providingwater to 100% of all citizens of India by 1991 hadto be revised and now stands at 90% access to urbanand 85% access to rural areas, respectively. Drinkingwater and sanitation nevertheless remain highpriorities on the government agenda.

Groundwater Depletion : facts and figuresFollowing findings focuses on the critical

scenario of ground water depletion :As per the findings in 1955 the availability of

fresh water in India was 5277 cum while in 2001 ithas depleted to 1820 cum.

Out of 650 BCM around 231 BCM water ispumped from ground water.

Around 575 liters of ground water per capitaper day is in demand, of which only 46 liters is usedfor domestic and industrial purposes while the restis consumed for irrigation.

The ground water is depleting at the rate of 2to 3 mts.per year.

Finally Meherana in Gujarat and Coimbatorein Tamil Nadu have lost their entire ground waterresources.

The state wise ground water deficit (cu.km/year) in India is depicted in following Table

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State Deficit (cu.km/ year)Rajasthan 32.6Maharashtra 22.0Gujarat 16.0Haryana 14.2Karnataka 12.7Punjab 4.0Other 2.8Total 104.3

Forth-coming Problems• In the Indus basin as a whole, groundwaterpumping is estimated to exceed recharge by 50%.• India is one of the leading countries in totalirrigated area and the third-largest grain producer,the number of shallow tube wells used to drawgroundwater was 3000 in 1960, and 6 million in1990.• Water Constraints on Irrigation : The eventuallack of water for irrigation could cut India’s grainproduction by 25%. 25% of India’s grain harvestcould be in jeopardy.• Pumped underground water is double the rateof aquifer recharge from rainfall.

Following are the critical ground water deficitproblems observed in various states of India

The ground water availability and the projecteddeficit in India are shown in Fig.-1. It can be seenfrom the figure that since 1951 the per capita wateravailability has rapidly decreased almost three timesin fifty years in the year 2001, while the futureprojected availability is expected to be 1140 cu.mwhich is almost twice less than observed in 2001.However, this would much depend on increase/decrease in pumping and our earnestness toimplement the water harvesting methods.

Presented below are the ground water deficitproblems observed in the various states of India: -• India’s use of ground water in 1973-74 was120-130 cu.km / year (80% for irrigation).• 65% of Haryana in India sits over saltygroundwater.• In southern India, groundwater levels arefalling 2.5-3 m/ years and between 1946-86; thewater table in parts of Karnataka dropped 40 m whilein the state of Tamil Nadu, ground-water levels have

dropped 25-30 m. in a decade. The major utilizationis for agriculture in Tamil Nadu, which has causedthe water table to drop close to 30 meters in a decade.• While it is estimated that Delhi will run out ofgroundwater by 2015 at current rates. In Ludhianadistrict of Punjab, the water table is dropping nearly1 m annually; water tables are dropping by underone to several meters per year in much of northernIndia’s Punjab, Haryana and Uttar Pradesh.• The position of most of the villages in India ismore pathetic where the major dependence of watersupply for the domestic and irrigation purposes isthe dependence on ground water• India’s irrigation water came from less than 30% groundwater in 1951 but over 40 % in 1980.• India’s potential surface water resource = 700-800 cu.km / year.• India’s potential utilizable ground-waterresource = 350 cu.km / year.• India’s rainfall = 110 cm / year. Ave. surfaceflow = 1800 cu.km / year. Inflow from neighboringcountries accounts for 200-cu.km / year of this 1800.Storage capacity (mid-1970s) = 160 cu.km. India’swater utilization = 250 cu.km / year (1974). 100cu.km of this was from storage; 150 from rivers andstreams. Irrigation accounted for 240-cu.km / yearof this utilization. (95 cu.km were used in 1951)Estimated surface water utilization in 2000 = 500cu.km / year, including 420 cu.km / year forirrigation.• Of 1.33 million km2 of land being cropped,240,000 km2 are irrigated, but only 50% of this hasan assured supply of water. 90,000 dug wells, 30,000shallow tube wells, and 9500 deep wells have beeninstalled in the past 15 years. The limited watersupply encourages inadequate leaching of land anda resultant increase in soil salinity. Indian per-capitawater supplies fell by roughly half during 1955-90.• Sugarcane growers in the state of Maharashtratake 50% of available irrigation water supplies, eventhough they occupy only 10% of cropped land.• Water shortages plagued 17,000 villages in thenorthern Indian state of Uttar- Pradesh in the 1960s.By 1985 that figure had risen to 70,000. Similarly,in Madhya-Pradesh, more than 36,400 villageslacked sufficient water in 1980; in 1985 the numbertotaled more than 64,500. In the western state ofGujarat, the number of villages short of water tripledbetween 1979 and 1986, from 3,840 to 12,250 and

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over-pumping by irrigators caused saltwater to invadethe aquifer.

Why Rain Water HarvestingUnavailability and inadequacy of surface water

and to meet our demands, we have to depend onground water.

Due to rapid urbanization and concretecovering over the land the infiltration of rainwaterinto the sub-soil has decreased drastically andrecharging of ground water has diminished.

Over-exploitation of ground water resource hasresulted in decline in water levels.

To avoid the situation of temporary floods orstagnation of water in urban areas even for a shortduration of rainfall.

To enhance availability of ground water at aspecific place and time.

To arrest saline water intrusion.Improvement of the water quality, conservation

and augmentation of the ground water aquifers.Sustaining the moisture content in the subsoil

so as to minimize the cracks during dry periods.To improve the vegetation cover.To raise the water levels in dug wells and bore

wells that are drying up.Different methods of Roof Top Rain water

Harvesting.

There are two main techniques of rainwaterharvestinga) Storage of rainwater on surface for future use.b) Recharge to ground water.

Following are the structures generally used forthe rainwater harvesting1. Recharge Pits: Recharge pits are constructedfor recharging the shallow aquifers. These areconstructed 1 – 2 m. wide and 2 - -3 m. deep whichare backfilled with boulders, gravels and coarsesand.2. Recharge Trench: These are constructed whenthe permeable strata are available at shallow depths.Trench may be 0.5 to 1 m. wide, 1 to 1.5 m. deepand 10 to 20 m long depending upon the availabilityof water. These are backfilled with filter materials.3. Open wells: Existing open wells may beutilized as recharge structures and water should passthrough filter media before putting it into open well.4. Hand Pumps: The existing hand pumps maybe used for recharging the shallow / deep aquifers,if the availability of water is limited. Water shouldpass through filter before diverting it into handpumps.5. Recharge Wells: Recharge wells of 100 to 300mm. Diameter are generally constructed forrecharging the deeper aquifers and water is passedthrough filter media to avoid choking of rechargewells.6. Recharge Shafts: For recharging the shallowaquifers, which are located below clayey surface,recharge shafts of 0.5 to 3 m. diameter and 10 to 15m. deep are constructed and back filled withboulders, gravels and coarse sand.7. Lateral shafts with bore wells: For rechargingthe upper as well as deeper aquifers lateral shafts of1.5 to 2 m. wide and 10 to 30 m. long depending

Different methods of Roof Top Rain water Harvesting

Deserted wells

Open Wells

Bore wells

Hand Pumps

Recharge pits

Recharge trenches

Recharge shafts

Recharge wells

Rain Water Harvesting Techniques

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upon availability of water with one or two bore wellsare constructed. The lateral shaft is back filled withboulders, gravels and coarse sand.8. Deserted wells: Recharge water is guidedthrough a canvas pipe of 100 mm diameter to thebottom of well or below the water level to avoidscouring.

Ideal Conditions for Rain Water Harvesting andArtificial Recharge to Ground Water• Most suitable for the urban areas whereadequate space for surface storage is not available.• Water level is deep enough (greater than 8m.)an adequate surface storage is available.• Permeable strata is available at shallow /moderate depth.• Where adequate quantity of surface water isavailable for recharge to ground water.• Where there is possibility of intrusion of salinewater especially in coastal areas.• Where the evaporation rate is very high fromsurface water bodies.• Where the ground water quality is bad.

Conclusion and suggestionsThe current paper discusses the ground water

availability, deficit and its future prediction for India.Also, importance and various harvesting techniqueshave been discussed. Thus in the current scenarioof severe water crises implementation of rain waterharvesting technique can be helpful in solvingfollowing problems :• An ideal solution to water problems in areashaving inadequate water resources.

The ground water level will rise.• Mitigates the effects of drought and achievesdrought proofing.• Rainwater harvesting can reduce stormdrainage load and flooding in city streets.• Flooding of roads is reduced.• Rainwater is bacteriologically pure, free fromorganic matter and soft in nature, so can be utilizedfor drinking purposes.• Soil erosion will be reduced.• Saving of energy per well for lifting of groundwater – a one-meter rise in water level saves about0.4 kwh of electricity.

• The structures required for rainwater harvestingare simple and economical. Also suit in anyenvironment.• Rainwater harvesting provides a water supplybuffer for use in times of emergency or breakdownof the public water supply system.

References• Artificial Recharge in India, A Publication of NationalGeophysical Research Institute, Hyderabad.• Asati S.R., “A case study on Rooftop rainwaterHarvesting,” Proceedings in National Conference andsustainable Development, L.A.D. and Smt.R.P.College forwomen, Nagpur dated 16-17 Dec.2005.• Asati S.R., and Sharma N.S.”Roof top RainwaterHarvesting: A case study,”proceedings in 38th AnnualConvention of I.W.W.A. hold at Jaipur (Rajasthan), 06-08 Jan2006.• Ashtankar T, Kelkar P and Nanoti M, ., “RainwaterHarvesting in Urban Areas- A Review ,” proceedings in38th Annual Convention of I.W.W.A. hold at Jaipur(Rajasthan), 06-08 Jan2006.• C.G.W.B., Manual on Artificial Recharge of Groundwater, March 1994, Technical Series M.No-3.• Dainik Bhaskar-News Paper, 28th June 2004.• Development of Monomolecular Film to Act asEvaporation Retardant and Prevent Water fromEvaporating from large Water Bodies Economically”,Project No. ID/17/95 sponsored by Ministry of WaterResources, Govt. of India.• Husiman L. & Olsthoorn T.N., “Artificial GroundwaterRecharge”, Pitman Advanced Publishing Program.• IWWA proceeding of 33rd Annual Convention Theme,“Water for New Millennium”.• Mahajan G., “Ground Water Recharge”, AshishPublishing House, New Delhi.• Pingle S.S. “Water Harvesting- The Need of the Hour,”Proceedings in National Conference and sustainableDevelopment, L.A.D. and Smt.R.P.College for women,Nagpur dated 16-17 Dec.2005.• National Drinking Water Mission, “Water HarvestingSystem Reference manual”.• Rainwater Harvesting, A Publication of nationalInstitute of Hydrology, Roorkee• Todd D. K., “Ground Water Hydrology”, John Wiley& sons• Trivedi S.H and Bhavnani H. V., “Artificial GroundWater Recharge through Roof top Rainwater Harvesting:A case study,” proceedings in 38th Annual Convention ofI.W.W.A. hold at Jaipur (Rajasthan), 06-08 Jan2006.

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IntroductionRain water harvesting is defined as the

collection of runoff and its use for the irrigation ofcrops, pastures and trees, and for livestockconsumption. As long as mankind has inhabitedsemi-arid areas and cultivated agricultural crops, ithas practiced some kind of water harvesting. Basedon “natural water harvesting” the use, of thewaters of ephemeral streams was already the basisof livelihood in the arid and semi-arid areas manythousands of years ago, allowing the establishmentof cities in the desert .The European expansion,especially the technological development since1850, lead to a steady increase in area under“classical” irrigation techniques with preference tolarge schemes. The classical sources of irrigationwater are often at the break of overuse and thereforeuntapped sources of (irrigation) water have to besought for increasing agricultural productivity andproviding sustained economic base. Waterharvesting for dry-land agriculture is a traditionalwater management technology to ease future waterscarcity in many arid and semi-arid regions of world.

1. Basic Concept1.1 General concept

Water harvesting is applied in arid and semi-arid regions where rainfall is either not sufficient tosustain good crop and pasture growth or where, dueto the erratic nature of precipitation, the risk of cropfailure is very high. Water harvesting cansignificantly increase plant production in droughtprone areas by concentrating the rainfall/runoff inparts of the total area. The intermittent character ofrainfall and runoff and the ephemerality offloodwater flow requires some kind of storage. Theremight be some kind of interim storage in tanks,cisterns or reservoirs or soil itself serves as areservoir for a certain period of time.

Water harvesting is based on the utilization ofsurface runoff; therefore it requires runoff producingand runoff receiving areas. In most cases, with theexception of floodwater harvesting from far awaycatchments, water harvesting utilizes the rainfallfrom the same location or region. It do not includeits conveyance over long distances or its use afterenriching the groundwater reservoir. Water

20. Rain Water Harvesting : A Viable Solution To Conserve Water

*Rishab Mahajan **Prof. Shakti Kumar ***Dr. R. K. KhitoIiya

*Pre-final Year **Professor ***Professor & Head, Post Graduate Environmental Engineering DepartmentDeptt. of Civil Engineering, Punjab Engineering College, Chandigarh – 160 012

Abstract :The problem of water shortage in arid and semi-arid regions is one due to low rainfall

and uneven distribution through out the season, which makes rain fed agriculture a riskyenterprise. Rain water harvesting for dry-land agriculture is a traditional water managementtechnology to ease future water scarcity in many arid and semi-arid regions of world. Thepaper discusses the use of water harvesting as an effective tool for water management. Thevarious forms of water harvesting have been elucidated. The common goal of all forms is tosecure water supply for annual crops, pastures, trees and animals in dry areas without tappinggroundwater or river-water sources. As the appropriate choice of technique depends on theamount of rainfall and its distribution, land topography, soil type and soil depth and localsocio-economic factors, these systems tend to be very site specific. The water harvesting methodsapplied strongly depend on local conditions and include such widely differing practices asbunding, pitting, micro catchments water harvesting, flood water and ground water harvesting.


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harvesting projects are generally local and small scaleprojects.

1.2 NecessitiesThe main goals of water harvesting are:1. Restoring the productivity of land which suffersfrom inadequate rainfall.2. Increasing yields of rain fed farming3. Minimizing the risk in drought prone areas4. Combating desertification by tree cultivation5. Supplying drinking water for animals.

2 Techniques of Rain Water HarvestingThe various rain water harvesting techniques

can be broadly classified into following sixcategories.1. Rooftop water harvesting2. Water harvesting for animal consumption3. Inter-row water harvesting4. Microcatchment water harvesting5. Medium-sized catchment water harvesting6. Large catchment water harvesting.

2.1 Roof top water harvestingRain “harvested” from the roofs of buildings

including greenhouses is, in many locations, a veryvaluable resource being used mainly for drinkingand domestic purposes. Fig. 2 shows a typical rooftop harvesting system.

The various types of roof top rain waterharvesting are as follows :2.1.1 Component System

This system enables custom building fromseparate components giving great flexibilityenabling the system to be adapted for manysituations regardless of location of storage tankrealative to building.

2.1.2 Module SystemThis type of system differs in that they do not

replenish the storage tank with main water. Insteadthere is an integral main water cistern which thepump draws from when there is insufficient waterin storage tank.

2.1.3 Hybrid SystemHybrid system comprises a module unit with

an additional submersible pump located inunderground storage tank.

2.2 Water harvesting for animal consumptionAncient dwellers harvested rain water for

human and animal consumption by redirecting thewater running down hill slopes into cisterns.Presently, this tradition is still practiced in manyregions, but where the means are available, surfacesused for rainwater collection are usually eitherphysically compacted, chemically treated or coveredto increase runoff volume:(i) Clay soils are well suited for compaction. Thesurfaces are shaped, smoothened and thencompacted e.g. by tractor and rubber-tired rollers.(ii) Sodium salts, wax, latexes, asphalt, bitumen,fiberglass and silicones can be used as sealants onsoils which do not swell with moisture (Frasier1994). Plots treated with sun-melted granulatedparaffin-wax yielded about 90 percent of the rainfallas runoff, compared to 30 percent from untreatedplots.(iii) Concrete, plastic sheeting, butyl rubber andmetal foil can also be used to cover the soil forFig. 2 : Roof top rain water harvesting

Fig. 1 : Annual precipitation ranges for different formsof water harvesting in summer rainfall areas

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“Matuta” (East Africa). The ridges of about 0.40 mheight are built 2 to 20 m apart, depending on slope,soil surface treatment, general CCR and type of cropto be grown. The catchment area should be weededand compacted; the crops are either grown in thefurrow, along the upper side of the bund or on topof the bund. On sloping land, this system isrecommended only for areas with a known regularrainfall pattern; very high rainfall intensities maycause breakages of the bunds. Crops cultivated inrow water harvesting systems are maize, beans,millet, rice or (in the USA) grapes and olives (Paceyand Cullis 1986, Finkel and Finkel 1986, Tobby1994). The preparation of the land for inter-rowwater harvesting can be fully mechanized.

2.4 Microcatchment systemsMicrocatchment water harvesting (MC-WH)

is a method of collecting surface runoff from a smallcatchment area and storing it in the root zone of anadjacent infiltration basin. This infiltration basinmay be planted with a single tree, bush or withannual crop.

Fig 4. Illustrates a microcatchment system. Thewater collected from different parts of the catchmentarea in stored as shown in the figure.

rainwater harvesting. Gravel may protect theunderlying membrane against radiation and winddamage.

The runoff water is collected in lined or unlinedpits down the slope of the catchment area (Fig. 2),

Fig 3. Rainwater harvesting systemfor animal consumption

2.3 Inter-row water harvestingInter-row water harvesting is applied either on

flat land or on gentle slopes of up to 5 % having soilat least 1 m deep. The annual rainfall should not beless than 200 mm/year. On flat terrain (0-1 %inclination) bunds are constructed, compacted and,under higher-input conditions, treated withchemicals to increase runoff. The aridity of thelocation determines the catchment to cropping ratio(CCR), which varies from 1:1 to 5:1 (Fig. 3).

On sloping land (1 - 20% inclination) thesesystems are called “contour ridges” (USA) or

Fig. 4. Various forms of flat-land inter-row waterharvesting increasing CCR/aridity of location.

The system shown in the Fig was given by Ben-Ashler [1] and has the following parameters.1. Catchment Area = 3 - 250 sq. m2. Cropping Area= 1 - 10 sq. m3. Catchment: Cropping Ratio = 3: 1 -25:14. Precipitation =150- 600 mm/a5. Slope = 1 - 20%

Fig 5 : Negarin type Microcathment system

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2.5 Large catchment water harvestingLarge catchment water harvesting comprises

systems with catchments being many squarekilometers in size, from which runoff water flowsthrough a major wadi (bed of an ephemeral stream),necessitating more complex structures of dams anddistribution networks.

Two types are mainly distinguished:1. Floodwater harvesting within the stream bed.2. Floodwater diversion.

2.5.1 Floodwater harvesting within the streambed

Floodwater harvesting within the stream bed”means blocking the water flow to inundate the valleybottom of the entire flood plain, to force the waterto infiltrate and use the wetted area for cropproduction or pasture improvement.

3. PARAMETERS FOR IDENTIFICATIONOF SUITABLE RAIN AREAS.

The selection of suitable areas and techniquesfor rain water harvesting is of utmost importance toderive the maximum benefits from the scheme.

The most important parameters to beconsidered in identifying areas suitable for rain andfloodwater harvesting are as follows:

3.1 RainfallThe knowledge of rainfall characteristics

(intensity and distribution) for a given area is oneof the pre-requisites for designing a water harvestingsystem. The availability of rainfall data series inspace and time and rainfall distribution are importantfor rainfall-runoff process and also for determinationof available soil moisture. A threshold rainfall events(e.g. of 5 mm/event) is used in many rainfall runoffmodels as a start value for runoff to occur. Theintensity of rainfall is a good indicator of whichrainfall is likely to produce runoff. Useful rainfallfactors for the design of a rain- or floodwaterharvesting system include:(1) Number of days in which the rain exceeds thethreshold rainfall of the catchment, on a weekly ormonthly basis.

2.5 Medium-sized catchment water harvestingWater harvesting from medium-sized

catchments (1,000 m2 - 200 ha) is also known as“water harvesting from long slopes”, as “macro-catchment water harvesting” or as “harvesting fromexternal catchment systems”.

The various characteristics of this type ofsystem are1. A CCR of 10:1 to 100:1; the catchment beinglocated outside the arable areas.2. The predominance of turbulent runoff andchannel flow of the catchment water in comparisonwith sheet or rill flow of micro catchments.3. The partial area contribution phenomenonwhich is not relevant for micro catchments.4. The catchment area may have an inclinationof 5 to 50 %; the cropping area is either terraced orlocated in flat terrain.

Fig. 6 shows a hillside conduit type systemwhich is adopted in areas having a precipitation of100-600 m.

2.5.2 Floodwater diversionFloodwater diversion means forcing the wadi

water to leave its natural course and conveying it tonearby areas suitable for arable cropping.Floodwater diversion techniques were alreadyapplied several thousand years ago.

Fig. 7 : Flood Diversion Technique

Fig 6. Hill Type Conduit System

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(2) Probability and occurrence (in years) for themean monthly rainfall.(3) Probability and reoccurrence for the minimumand maximum monthly rainfall.(4) Frequency distribution of storms of differentspecific intensities.

3.2 Land use or vegetation coverVegetation is an infiltration rates which

consequently decrease the volume of runoff.Vegetation density can be characterized by the sizeof the area covered under vegetation. There is a highdegree of congruence between density of vegetationand suitability of the soil to be used for cropping.

3.3 Topography and terrain profileThe land form along with slope gradient and

relief intensity is other parameters to determine thetype of water harvesting. The terrain analysis canbe used for determination of the length of slope, aparameter regarded of very high importance for thesuitability of an area for macro-catchments waterharvesting. With a given inclination, the runoffvolume increases with the length of slope. The slopelength can be used to determine the suitability formacro or micro- or mixed water harvesting systemsdecision making.

3.4 Soil type & soil depthThe suitability of a certain area either as

catchments or as cropping area in water harvestingdepend strongly on its soils characteristics viz.(1) Surface structure; which influence the rainfall-runoff process(2) The infiltration and percolation rate; whichdetermine water movement into the soil and withinthe soil matrix, and(3) The soil depth incl. soil texture; whichdetermines the quantity of water which can be storedin the soil.

e) Hydrology and water resourcesThe hydrological processes relevant to water

harvesting practices are those involved in theproduction, flow and storage other importantparameter that affects the surface runoff. Variousstudies have shown that an increase in the vegetationdensity results in a corresponding increase ininterception losses, retention and of runoff from

rainfall within a particular project area. The rainfalling on a particular catchment area can beeffective (as direct runoff) or ineffective (asevaporation, deep percolation). The quantity ofrainfall which produces runoff is a good indicatorof the suitability of the area for water harvesting.

3.5 Socio-economic & infrastructureconditions

The socio-economic conditions of a regionbeing considered for any water harvesting schemeare very important for planning, designing andimplementation. The chances for success are muchgreater if resource users and community groups areinvolved from early planning stage onwards. Thefarming systems of the community, the financialcapabilities of the average farmer, the culturalbehaviour together with religious belief of thepeople, attitude of farmers towards the introductionof new farming methods, the farmers knowledgeabout irrigated agriculture, land tenure and propertyrights and the role of women and minorities in thecommunities are crucial issues.

3.6 Environmental and ecological impactsDry area ecosystems are generally fragile and

have a limited capacity to adjust to change [3]. Ifthe use of natural resources (land and water), issuddenly changed by water harvesting, theenvironmental consequences are often far greaterthan foreseen. Consideration should be given to thepossible effect on natural wetlands as on other waterusers, both in terms of water quality and quantity.New water harvesting systems may intercept runoffat the upstream part of the catchment, thus deprivingpotential down stream users of their share of theresources. Water harvesting technology should beseen as one component of a regional watermanagement improvement project. Components ofsuch integrated plans should be the improvement ofagronomic practices, including the use of good plantmaterial, plant protection measures and soil fertilitymanagement.

4. ConclusionsSubstantial amounts of rainfall in semi-arid

areas are lost (e.g. by evaporation from soilsurfaces), which could be utilized for agriculturalproduction. This could be achieved through water

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harvesting. Rainwater Harvesting have the potentialto increase the productivity of arable and grazingland by increasing the yields and by reducing therisk of crop failure. They also facilitate re- orafforestation, fruit tree planting or agroforestry. Withregard to tree establishment, rainwater andfloodwater harvesting can contribute to the fightagainst desertification. Most of these techniques arerelatively cheap and can therefore be a viablealternative where irrigation water from other sourcesis not readily available or too costly. Unlike pumpingwater, water harvesting saves energy andmaintenance costs. Using harvested rainwater helpsin decreasing the use of other valuable water sourceslike groundwater. Remote sensing and GeographicalInformation Systems can help in the determinationof areas suitable for water harvesting. The decisionmaking process concerning the best method

applicable in particular environmental and geo-physical conditions depends on kind of crop to begrown and prevalent socio-economic and culturalfactors.

References1. Ben-Asher, J. (1988). A Review of WaterHarvesting in Israel. World Bank Working Paper 2.WorldBank Sub-Saharan Water Harvesting Study,p. 47-69.2. Boers, T. M. and Ben-Asher, J. (1982). Areview of rainwater harvesting. Agric. WaterManagement.3. Oweis, T., A. Hachum, and J. Kijne. 1999.Water harvesting and supplementary irrigation forimproved water use efficiency in dry areas.4. Prinz, D., S. Wolfer.1999. Traditionaltechniques of Water Management.

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1. INTRODUCTIONWater is an excellent resource of nature, and it

can be made to serve various functions. Properlyplanned use of water may nourish our farms andforests, may run our turbines for generation of hydro-electric power, may help in preparing modernmedicines for cure of various ailments and diseases,may help in beautifying our surroundings andenvironments, etc. Besides, fulfilling the basicnecessities of life, properly harnessed and developedwater can enable us to lead an effluent and aluxurious life. It is in fact, an amazing fluid and canlead to an overall prosperity of a nation and that ofthe entire community as a whole. But, if not properlyharnessed or planned, the same useful servant maybecome wild or an enemy in the form of severestorms, floods, hurricanes, etc bringing disasters,devastations and catastrophes.

Proper planning is, therefore, absolutely

21. Technology to Effectively Utilize Rain and River Water throughAdvanced Ground Water Recharging Technique without Interlinking

of Rivers

*Chetan Hari Sharma


AbstractThe technology to effectively utilize rain and river water through advanced ground

water recharging technique is a system which club together nearly every engineering aspectrelated to it and utilizes them in the best possible way to serve the humanity.

It channelizes the floodwater and the water, which would otherwise mix with the sea,as a ground water reserve, so that it can be made available, to the whole country duringnon-monsoon months. As the pure water free from all impurities is stored under-groundtherefore a very huge percentage of water, which would have been evaporated if it had beenstored on the surface, can be saved.

In addition to all these capabilities the technology proves to be the gods blessing bygenerating electricity, through pollution free hydroelectric power plant in between the journeyof this harnessed water from the surface location to under-ground aquifers, extracting allthe additional energy which the water initially possess due to its potential head.

necessary so as to obtain from this servant, as manybenefits as possible, with minimum expenditure.Hence, the proposed proposal in this paper had beeninvented by me considering all the aspects of thebehavior of water resource and present engineeringcapabilities which ensures that the proposal is thebest one, and any other possible alternative will notbe better then the proposed one.

The purpose of the plan to effectively utilizerain and river water through advanced ground waterrecharging technique is to :[a] Reduce the extent of annual flooding at theflood prone areas, mainly of the Ganga andBrahmaputra Basin.[b] Solve the ground water related problems, suchas ground water depletion, pollution and qualitydeterioration, through rechargement of large amountof pure water, which would otherwise get wasted.[c] Boost agricultural productivity, as ground

Krishna Mandir, Cement Road, Sadar, Gandhi Chowk, Nagpur - 440 001 IndiaEmail: chetan hari [email protected]

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water irrigation’s contribution to agriculturalproductivity is some 45% higher then that made bythe surface irrigation in India.[d] Prevent seawater intrusion in the costal areaaquifers, which is mostly caused because of groundwater over exploitation.[e] Provide water for drought prone areas, and theregions where ground water level is depleting dueto over exploitation.[f] Generate additional hydroelectric power,approximately 50% more then the present country’shydroelectric power capacity.[g] Harness maximum possible amount of 1500BCM of floodwater, 700 BCM of water whichpresently gets evaporated and 300 BCM of balancewater, which presently remains unutilized.

2. PRESENT HYDROLOGICAL SCENARIOThe rapid growth in the demand of fresh water

driven by growth in the global population and ofthe economies has lead to this natural resourcesbecoming scarce in many parts of the world. As aresult, the ratio between the number of the peopleand the available water resource is worsening dayby day. By 2020, the global population is projectedto touch 7.9 billion, which is 50 percent longer thanthat in 1990. Because of this rapid growingpopulation the world may see more then six foldincrease in the number of people living in thecondition of water stress from 470 million today to3 billion in 2025.

In the global picture, India is identified as acountry where water scarcity is expected to growconsiderably in the coming decades further droughtconditions resulting from climatic variability causeconsiderable human suffering in many parts of thecountry in the form of scarcity of water for bothsatisfaction of domestic needs and for cropprotection.

Unlike the precipitation patterns in thetemperate regions of the world, precipitation in Indiais characterized by acute variation in both space andtime. In our country 80 percent of the annual run offis limited to brief monsoon period generally less than100 days. In total, country receives about 4000 BCMof water as precipitation annually out of which 700BCM are lost in evaporation and another 700 BCMare lost during the flow on the ground. Also, thelarge part of the water namely 1500 BCM flows into

the sea due to the floods, thus, the remaining availablewater is only 1100 BCM out of this ground waterrecharge accounts for 430 BCM per year and thepresent utilized surface water is 370 BCM thebalance unutilized water which can be harnessed is300 BCM.

A large part of the precipitation on the countryis received in the Himalayan Catchments of theGanga- Brahmaputra- Meghna (GBM) basis. Thedistribution of precipitation over the India ispredominately governed by the monsoon as a resultof which the north eastern water of the countryreceives substantially large precipitation incomparison with the north western, western andsouthern parts for example, the eastern part of GBMbasin Cherrapunji receives an annual precipitationof about 11,000mm while Ajmer just outside thewestern boundary of the GBM basin may receiveonly 200 mm of annual rainfall.

3. INDIA’S GROUND WATER SOCIO-ECOLOGY

The groundwater socio-ecology of India hasbeen at the heart of their agrarian boom; and thissocio-ecology is under siege. Much concern aboutthe problems of groundwater depletion, pollutionand quality deterioration is fueled by worries abouttheir environmental consequences. These are indeedserious; however, equally serious are theirconsequences for the sustenance of agrarianeconomies and millions of rural livelihoods that areprecariously dependent upon groundwater irrigation.India, Pakistan, Bangladesh and China account forthe bulk of the world’s groundwater use inagriculture. Indeed, while much public investmenthas been devoted to the creation of surface irrigation,the reality of India is that the bulk of its agrariangrowth in recent decades has been energized by arapid rise in groundwater irrigation through smallpumps and wells financed mostly through privatefarmer investments. A new analysis of Indianagriculture suggests that based on an Indian data setoffering the tentative macro-level test, groundwaterirrigation may contribute more to Indian agriculturalgrowth than even surface irrigation development.The model results support the hypothesis thatgroundwater irrigation contributes nearly 50 % moreto rural wealth creation than surface irrigation; fora 1,000 ha increase in the area under groundwater

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development has tended to be more ‘democratic’; ithas responded more to people’s needs and demandrather than to hydrological opportunity; it is linkedmore to population density than to the occurrenceof the resource. Finally, groundwater has provenmore amenable to poverty targeting than have largesurface irrigation systems; governments can designpump subsidies or build public tube wells, but notlarge canal systems, exclusively for the poorersegments. That’s why groundwater economy of Indiais the backbone of its increasingly productiveagriculture and rural livelihood systems.

Throughout India, however, regions that havesustainable groundwater balances are shrinking dayby day. Three problems dominate groundwater use:depletion due to overdraft; water logging andsalinization due mostly to inadequate drainage andinsufficient conjunctive use; and pollution due toagricultural, industrial and other human activity.Groundwater depletion has major environmentalconsequences; but it has important economicconsequences too. Declining water tables raise theenergy and capital costs of accessing groundwaterto prohibitive levels; in such regions, like NorthGujarat, entire agrarian economies face seriousthreat of extinction from the decline of groundwatersocio-ecologies. Water quality and health problems- such as very high fluoride and arsenic contents -have similarly immiserizing social impacts in India.

irrigation increases a district’s average agriculturalproductivity by Rs 23/ha, whereas adding 1,000 hato surface water irrigated area increases it only byRs 16/ha. Table below provides an alternative modeof comparing Agricultural Productivity and GroundWater Irrigation in India. In the ‘average’ districtwith 102,730 ha under groundwater and 79,230 haunder surface irrigation, Rs 2,363/ha of the averageproductivity, of Rs 10,460 is contributed bygroundwater irrigation, while only Rs 1,258 isexplained by surface irrigation.

Table -1 :Comparison of Agricultural Productivity and

Ground Water Irrigation in India

All in all, the analysis of Indian data exploresthat in the recent decades, of the agriculturalproductivity of a ‘representative’ (or typical) hectare,the portion contributed by groundwater irrigation isvery nearly twice that contributed by surfaceirrigation. It also shows that groundwater

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Unlike India countries like the US and Australia, thepresence of a small number of large users and lowpopulation density creates uniquely favorableconditions for some institutional approaches towork; but these break down in India, with its highpopulation density and multitude of tiny users. Forinstance, a stringent groundwater law that isenforced in Australia would come unstuck in Indiabecause of prohibitive enforcement costs. Europehas a high population density; but it is much morecomfortable than India in its overall water balance.Moreover, ground water is a little Importance insouth East Asia, which has abundant surface water.

Therefore, it is obligatory that like surfacewater, the groundwater resource too needs to beplanned and managed for maximum basin-levelefficiency.

4. FLOOD AND DROUGHT SITUATIONThe vast variation both in space and time in

the availability of water in different region of thecountry has created what is normally referred to asfood drought flood syndrome with some areasuffering from flood damages and other facing acutewater shortage, flood and drought affects vast areaof country transcending state boundaries. As perrecord after independence 70 droughts occurred incountry. Land over 80% of our country goes underdrought if there is a short fall of 5% rain in monsoon.Jodhpur, Banner, Charu district of Rajasthan isdrought hited for 31 out of 38 years. Floods normallyaffects, 8 major rivers valleys spread over 40 millionhectare of area in the entire country affecting nearly260 million people, similarly the drought affect 86million people who are spread in 14 states coveringa total 116 districts. This flood comes from the 1500BCM of water every year flowing during themonsoon season. If we have to prevent the damagedue to the flood and reduce the severity of drought,we have to harness this 1500 BCM of water anddistribute it to the drought-affected areas. If wesucceed in doing this, we will save Rs. 150 billionper annum which is spend on drought relief andRs.300 billion per annum which is spend on floodrelief by our country. The question that arises is howto harness the floodwater? And how to regulate theout flow of floodwater so that it does not go into seaand it is converted as useful water for the mankind.The answer is, through the project for technology

to effectively utilized rain and river water throughadvanced ground water recharging technique, whichemanates to bring a permanent solution to thenegative impacts or drought and floods. Such adesire must be considered without question, worthyof applause because satisfaction of domestic waterneeds should be considered as a human right and begiven the top priority.

4. ABOUT MY TECHNOLOGYMy proposal envisages the withdrawal of

flowing water through the river with the help of riverintake structure. It is necessary to construct suchriver intakes because when water is withdrawnthrough a conduit, from a river independently, andas such the entrance of the conduit is not an integralpart of the dam or any other related structure thanan intake structure is used for safe withdrawal ofwater from the river over a predetermined range ofpool levels and thus to protect the conduit from beingdamaged, trash, debris, waves, etc. The most suitableintake structures for this technology are: -[a] Wet intake tower[b] Dry intake tower

However, the dry intake towers are useful andbeneficial in the sense that water can be withdrawnfrom any selected level of the river by opening theport at that level. Since, the rain is uniformlydistributed over the entire basin therefore the runoff goes on increasing while making its way towardssea. Hence, these river intakes can be installed atsuch spacing that the withdrawal of water throughthese intake maintains the desired level of flowthroughout the river.

The water coming out from the conduit is sendto the water purification plant to improve the qualityof the water, in such plants water is passed throughnumber of treatments so that the water coming outof the plant when consumed for domestic purposesit would not result in any health hazard. The qualityof water can be defined and estimated by studying its1. PHYSICAL CHARACTERISTICS : Turbidity,colour, taste, odour and specific conductivity ofwater.2. CHEMICAL CHARACTERISTICS : Totalsolids and suspended solids PH value of water,hardness of water, sodium content of water.3. BACTERIAL AND MICROSCOPICCHARACTERISTICS : Aerobic bacteria, faultative

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bacteria, plankton (algae), protozoa, etc.It is necessary to purify water because through

this technology I had planned to preserve this waterin the ground water aquifer’s, so that whenever andwherever required this water can be extracted withthe help of pumps for domestic and other uses. Also,in the process of natural ground water recharging,the water while percolating below the ground surfacepasses through the voids of the rocks, and join watertable, which makes it automatically purified alongits passage. But, in this artificial rechargingtechnique water is directly passed to the undergroundlocation. Hence it most be purified first.

Depending upon the capacity of waterpurification plants water may be supplied to a singleplant from the number of river intake structure via,conduit pipe or water may be supplied to the plantfrom a single river intake structure. The waterreleased from the purification plant is impoundedby a reservoir having a dam constructed over it. Theconstruction of such reservoir may hand out in manyways.[a] Store a portion of the flood flows in such away as to play down the flood peaks at the areas tobe protected downstream.[b] To prevent difficulties to carry out theoperation, during high flows.[c] Fulfill the demand of hydroelectric power plant.[d] Direct water supply to the city, etc.

The reservoir is further connected to thewaterways, which acts as a passage through whichthe water is carried from the storage reservoir to thepowerhouse where electricity is generated, utilizingthe power of water. The water has two_forms ofenergy while flowing through the penstock, kineticand potential. The kinetic depends upon the massof water flowing and its velocity, while the forms ofenergy while flowing through the penstock, kineticand potential. The kinetic depends upon the massof water flowing and its velocity, while the potentialenergy exists as a result of difference in the waterlevel between the two points, which is known as“head” the hydraulic turbine convent kinetic andpotential energies possessed by the water intomechanical power. The hydraulic turbine is thus aprime mover which when coupled to a generatorproduces electric power.Since, in this technology our aim is to prevent floodsand deliver maximum possible mass of waterunderground to enhance the ground water level,therefore there is no limitation, in the amount ofwater to be used. Hence, we are provided with theample mass of water with us, which can producevery high kinetic energy. Also since we have totransmit water under ground therefore high headscan be attained resulting in tremendous amount ofpower generation.

FIG : MODIFIED HYDRO ELECTRIC POWER PLANT

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As such, it is a matter of concern that 59 yearsafter independence, more than fifty percent of allrural house hold in India do not have electricity anduse kerosene for lighting. Even for those rural areas,which are electrified, there is a tremendous shortageof power supply. Thus it is not uncommon for thoseareas to have 10-15 hours of black outs every day.There is a short fall of about 20,000 MW ofelectricity in the country and we require about1,40,000 MW of additional capacity by 2010. Thisproject will give a major contribution to overcomesuch energy crisis; it will be helpful to meet outenergy demands, by a 40-45% contribution innational power grids through, hydroelectricgeneration by 35,000-40,000 MW.

The water coming out from the draft tube ofthe hydroelectric power plant is discharged to theartificial underground reservoirs. Such reservoirs arecreated because of varying amount of valid spacesin the bedrocks where ground water accumulates.The rocks below the earth’s surface is the bedrockconsisting of many types of rocks, such as sandstones, granite, and limestone. Bed rocks can alsobecome broken and fractured, creating spaces thatcan be fill with water. And some bedrock, such aslimestone, is dissolved by water, which results inlarge cavities that fill with water.

In many places, considering vertical cross-section of the earth the rock is laid down in layersespecially in areas of sedimentary rocks. Some layershave rocks that are more porous than others, andhere water moves more freely in the horizontalmanner through the earth deep, in the bedrock thereare rock layers made of dense material such asgranite or materials that water has a hard timepenetration, such as clay. These layers may beunderneath the porous rock layers and thus, act as aconfining layer to retard the vertical movement ofwater. Since, it is more difficult for the water to goany deeper it tends to pool in the porous layers andflow in more horizontal direction across the aquifertowards regions having there aquifer with low waterlevel. In this way the aquifer in which the water isstored shall itself be act as the distribution systemfor carrying water from one place to another withor without any minor modification in its flow patternand so such necessity of constructing pipelines orcanals (as required in the project of interlinking ofrivers) is completely eliminated, therefore cost due

to huge distribution network and the large area ofland which would be utilized in constructing suchcanals is saved. Therefore through my technologyof artificial ground water storage the followingbenefits can be obtained.[a] The present ground water decline rate is as highas 1.5 meters per year in some parts, has not onlydestroyed many wells but also resulted increasedcost from water pumping, this problem can berectified only through my technique.[b] Since, in India some 60% of total agriculturalwater comes from the ground water, which accountsof over half of total irrigated area, increase in thewater table can give new boost to agriculturalgrowth.[c] This type of ground water managementrequires no or sometimes very minor modificationin the aquifer to distribute the water to the droughtaffected regions such as Rajasthan and Gujaratwhich are under havoc and misery.[d] The water lost in evaporation from anunderground reservoir of this technology is muchless than the water lost from a surface reservoir.[e] My technology will prove to be more amenableto poverty targeting than have large surface irrigationsystem, since government can design pump subsidiesor build public tube wells but not large canal systemexclusively for the poorer segments.[f] The ground water development as tented to bemore democratic; it can respond more to people’sneeds and demand rather than hydrologicalopportunity; it is linked more to population densitythan to occurrence of the resource.[g] More than 65% of India’s total ground wateris affected by excessive fluoride content, resultingin fluorine related diseases, excess fluoride indrinking water also causes bone related problemsand ground water of West Bengal has high arseniccontent, this has become a major water quality andhealth issue effecting huge areas of population,through this technology such problems can be solvedby keeping the concentration of fluoride, arsenic andother chemicals get diluted and much purer watercan be made available.[h] The sea water intrusion on India’s coasts,specially Gujarat’s Savrashtra region, Tamil Nadu’sMinjur aquifer, coastal areas of Indus basin isthreatening the ecology of important wet lands,including Mangrove forests of over 1,30,000 ha,

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ground water over-exploitation is the main cause ofthese sea-water intrusion. The raising of water tableby this artificial recharging method may help inbuilding pressure barriers to prevent seawaterintrusion in the coastal areas.[i] No space is required to build such reservoir.

In another form of such type of project, thereservoir can be constructed directly across the river.The water from the reservoir is extracted and sendto water purification plant and this water after thepurification is send to another reservoir which isfurther connected to the same system ofhydroelectric power plant and ground water aquiferas discussed above.

In such types of construction there is no needto build river intake structure and are suitable forimplementation in the region where there is highprobability of sudden rise in the run off due to veryheavy precipitation. As, in the previous method wewhere sending the water at the water purificationplant with the help of conduit and then transmittingthis purified plant would do not be able to managetheir operation due to devastating floods, as theycould not work above their capacity. This couldresult in little higher flood peaks, all these problemscan be avoided by building a reservoir fitted withdam over it, directly over the river. The water fromthe reservoir is extracted according to the capacityof water purification plant and the requirement ofhydel power plant and then after purification is sendto a closed large tank from where it can be suppliedto the power plant and so on.

5. MOST SUITABLE LOCATIONSIndia is blessed with the wonderful gift by the

nature in the form of Himalayan Mountain in thenorth, which plays a very significant role inproviding the supplies of water the human societiesneeds. The Himalayas is the source of many largerivers like Yangtse, Irrawadi, Yarlung, Tsangpo,Brahmaputra, Ganga, Indus, Amu Darya, etc. Indeedthe Himalayas can be called the water tower of Asiathe amount of water that India receives because ofsuch geographical conditions is capable to satisfyits presents and future water needs comfortably ifharassed effectively. Indeed, it is true that naturehad given us the solution of each and every problem,now it is the duty, of we engineers and scientists to

explore the ways through which the availableresources can be utilized in the best possible mannerto fulfill our needs. In total India has as many as 12major rivers whose total catchment area is 252.8million hectare (mha) of the major rivers; the Ganga-Brahmaputra-Meghna system is the biggest with thecatchments area of about 110 mha which is morethan 43 percent of the catchment area of all the majorrivers in the country. The other major rivers withcatchment area more then 10 mha are Indus (32.1mha), Godavari (31.3mha), Krishna (25.9mha), andMahanadi (14.2mha). The catchment area ofmedium rivers is about 25 mha and Subernarekhawith 1.9mha catchment area is the largest riveramong the medium rivers in the country. About 40percent of utilizable surface water resources arepresently in Ganga-Brahmaputra-Meghna system.The distribution of water resources potential in thecountry shows that as against the national per capitaannual availability of water as 2,208 cubic meters,the average availability in Brahmaputra and Barakis as high as 16,589 cubic metres while it is low as360 cubic meters in Sabarmati Basin. Brahmaputraand Barak basin with 7.3 percent of geographicalarea 4.2 % of population of the country has 31% ofthe annual water resources per capita annualavailability for rest of the country excludingBrahmaputra and Barak basin works out to about1,583 cubic meters. Any situation of availability ofless than 1,000 cubic meters per capita is consideredby international agencies as scarcity conditionCauvery, Pennar, Sabarmati, East flowing rivers andWest flowing rivers are some of the basins whichfall into this category.

The technology to effectively utilize rain andriver water through advanced ground waterrecharging technique can be implemented at thelocations where, per capita annual availability ofwater is much greater than national per capita annualavailability of water. At present, most of theselocations are selected for the project of interlinkingof Indian rivers. In this project 36 main dams hadbeen planned to be constructed and hydropower of34000 MW is estimated to be generated. At all the30 locations where surplus river water is planned tobe supplied to the rivers with low flow rate, myproject can be implemented and instead of supplyingsuch water to other rivers, the complete water canbe stored in the ground water aquifer.

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6. VARIOUS PROPOSALS FORINTERLINKING OF RIVERS

6.1 PENINSULAR RIVERS DEVELOPMENTIt is planned by national water development

agency to direct about 19 KM3 of surplus flow ofMahanadi River to the Godavari system and tofurther transfer 38 KM3 from Godavari and itstributaries to the Krishna river downwards South.Another part of this proposal is to divert a part ofthe surplus water of West flowing rivers of Keralato the East and generate hydropower. The thirdsegment envisages construction, storage to interlinksmall rivers flowing along the West coast north ofMumbai and South of Tapi. The fourth partenvisages interlinking of the Ken and the Chambal.The proposal of peninsular river developmentprovides additional surface water in irrigationbenefits of 13 mha and generation of 4000 MW ofpower. The addition, about the 3mha area could beirrigated with ground water.

6.2 HIMALAYAN RIVER DEVELOPMENTOut of the total water resource of the GBM

basin of about l000 maft, less than 10% there of isbeing consumptively used at present. It is estimatedthat by providing large storage floods can bemoderated providing substantial benefits of floodcontrol in the downstream regions. About 600KM3

of storage is required to fully harness the waterresources of the GBM basin, but through interlinkingprocess only 215KM3 of storage could be providedin India, Nepal and Bhutan on the GBM system.

It is proposed to divert the water fromBrahmaputra, Ganga, and Subernarekha to RiverMahanadi by five river links and then to the southernrivers. The second segment consists of interlinkingtributaries of Ganga, as another part of the proposalis to Interlink Sharda, Yamuna, and Sabarmati Riverby canals.

If the regional view is taken, India can getadditional irrigation of 22 mha after fully meetingthe needs of water in the other three countries.Besides, this hydropower generation of about30000MW is possible.

7. BENEFITS OF TECHNOLOGY TOEFFECTIVELY UTILISE RAIN AND RIVERWATER THROUGH ADVANCED GROUND

WATER RECHARGING TECHNIQUE OVERINTERLINKING PROJECT :[a] The project of interlinking of rivers soundsgood but involves a massive expenditure of aboutRs. 5,60,000 crores, for a developing country likeIndia if such a large amount is saved then it can beused for development in other areas, where as myproject’s cost would be negligible in front of it sincecost of construction of large canals are eliminated.[b] For the construction of canals nearly 4.5 lakhpeople will be displayed from there homes,farmlands and offices and a large cost will beinvolved in there rehabilitation for the interlinkingproject, while such cost is not involve in my project.[c] Though, through this project water would besupplied to the rivers having low run off, but it wouldbe of no use, because with the addition of sewagewater and the water from the industrial waste thenew water system will not remain fit for drinkingand other domestic purposes for much time, but inmy technology water can be extracted from anywhere, any time with the help of tube wells and canbe consumed for domestic purposes, since it iscompletely purified.[d] Whenever it will become necessary to use thewater through flow channel of the linked rivers, forthe domestic needs it must be purified first, thepurification cost of this water would becomparatively higher then what would be requiredin my project, since after flowing over a largedistances, a huge percentage of impurities will mixwith this water.[e] The major drought affected areas of India areRajasthan and Gujarat, where there is extreme needto supply water as soon as possible, the interlinkingproject must have been planned to transmit most ofthe surplus flow to those regions, to prove itselfbeneficial to mankind, but no major steps are to betaken considering this aspects, while through myproject sufficient water can be supplied to the groundwater aquifer of each and every regions whereground water level is depleting.[f] India manages to loose more quantity of waterthen, what it needs to satisfy its annual domesticneeds through evaporation. The interlinking involvesconstruction of 30 links extending up to 10,880 KMoccupying about 3.42 million KM2 of thegeographical area, through this project such a largeamount of additional water surface area would be

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exposed to atmosphere making evaporation of watera predominating problem. Indeed, it is a verywasteful way of supplying domestic water needs.While, evaporation looses are completely absent inmy project.[g] Since, whole of the water even after interlinkwill ultimately merge into the sea; all the effortsutilized for digging such large holes to form canalsand the large money employed in this project ofinterlinking will get ruined. Where as, through myproject every single drop of water, which isharnessed and send underground can be utilizedefficiently.[h] The period of implementation for the giganticproject of interlinking of rivers as given by SupremeCourt order, is mere 12 years. But experts say thatinterlinking of rivers is highly complex process withhuge backward and forward and inter-sectorallinkages that may be accomplished incrementallyover to next 50-100 years. Where as, since myproject is free from all such complexities, it can beimplemented at much less time.[i] Interlinking project would not be cost effectiveoption for domestic water security in Drought-Proneareas as it tries to supply domestic water throughcollection at far away points and distribution throughlong canals or existing river bed, with the help ofheavy pumping machineries. However, it is quiteclear that both financial cost and the amount of waterlost, my technology would be much effective.[j] Ground water gets distributed equally in theregions where water level gets depleted thereforeharnessing of water through my technique will notgive birth to conflicts isolated to water which couldresult due to interlinking of rivers.[k] The submergence of forests due to interlinkingproject may lead to serious implications in terms ofbio-diversity loss; there are no such problems withmy project.

8. CONCLUSIONThe technology to effectively utilize rain and

river water through advanced ground waterrecharging technique is a project that would provide

us with uncountable benefits. It is capable of solvingall the water related problems not only through Indiabut also from the whole world and in addition tothis it would produce a large capacity of pollutionfree hydro electricity. I had tried to explain its everyaspects briefly in this paper.

As such, for a country like India, where onepart is soaked in water, while other parts fears theproblems of drought. This type of mega project isrequired in order to have uniform distribution ofwater. Our country with world’s second largestpopulation and ever growing demand of food andwater, my project is required. On the other hand theambitious plan of inter basin transfer; as per theexperience of other countries argumentation of wateris a very wasteful and costly option. This projectwill have a large social, environmental ramification.Heavy pumping machinery required continuousenergy supply. It is very difficulty to give constantpower supply in the period of energy crisis. So itwill be impossible to cover stage pumping. Also,remarkable change in eco-system will affect humanand animal life. At last, a major part of this preciousand scarce water resource will get wasted, unutilizeddue to evaporation and mixing into the sea.

The project of interlinking of rivers is like afew lines drawn on the map of country and I amconfident that it will remain the same even afterimplementation, with very less benefits then whatcan be achieved through my technology of artificialground water recharging. I request the government,engineers, scientists and citizens of India to pleasetake each and every point, which I had, mention inmy paper, with little seriousness. As the project ofinterlinking of rivers may not effect most of usdirectly, and a few, of us will be displaced. However,everyone living in the country will be affected bythe long-term consequences of the project.

I hope that my project of technology effectivelyutilized rain and river water through advance groundwater recharging technique would be appreciatedby each and every community in India ad well asabroad with open mind and open heart as it is anessential requirement for the prosperity of the nation.

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22. Rainwater Harvesting and Northeast India : A Simple andCheapest Method

*Shukla Acharjee **Mangesh G. Waghmare

*Department of Applied Geology, Dibrugarh University, Dibrugarh-786006, Assam, India**B.E (Civil), X83/14, Godrej Colony, Vikroli (E), Mumbai-400079, India

only fraction of water. Huge quantity of rainwaterfinds its way ultimately to sea through streamswithout much contribution to aquifer system.

Hence, the only alternative is to harvest &conserve this precious gift of the nature byscientifically designed Rain Water Harvestingstructure. Ground water is the water stored in sub–surface level in soil or rock formation of earth. It isobserved that the dense forest cover is reducing forlast few decades. And hence, capacity of the soil tohold water is also reduced. In addition to this, heavy

ABSTRACTThe present drought like situation in the lower Assam Brahmaputra Valley compelled

the people residing here to change their mindset that Northeast India won’t experiencedrought. More than five lakhs farmers were affected by the unusual drought this year. Untilrecent past the valley was considered to be the most vulnerably affected by flood twice ayear. However, due to global climatic change and other such factors now this region is alsoexperiencing drought like situation. Therefore, it is high time that people should wake upand culture their mind to face any such situation in near future and use the resourcesjudiciously and learn the concept of sustainable development to preserve the natural resourceavailable to them for future generation. Here the authors have designed a simple model andthe cheapest method of rainwater harvesting keeping in mind the amount of precipitation,topography, soil, depth, vegetation, cost of construction, storage and distribution systemfor the poor people of northeast India. As rainfall is the main source of surface water andits conservation is essential, therefore rainwater harvesting is one of the most promisingtechniques for collection of excess runoff. In this northeastern part, bamboo is consideredthe green gold. From storage to groundwater recharge in the present model bamboo hasbeen used which is easily available here. This technique of rainwater harvesting would bevery cheap for the farmers in particular and the masses in general living in the hilly regionsas well as in the plains of northeast India.KEYWORDS : Rainwater harvesting, sustainable development, ground water recharge,bamboo.

Corresponding Author: [email protected]

INTRODUCTIONWater is a key for sustainable watershed

development and of all the natural resources; waterplays a very vital role in lives of human beings.Presence and absence of water clearly determinesthe culture and growth of community and a healthyeconomy. Rain is the only natural source of freshwater in India. Over all the percentage of rechargingof ground aquifers is 5-20% of total rain. It alsodepends on terrain, topsoil condition, sub- surfaceformation & rainfall pattern etc. Topsoil can hold

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extraction of ground water is leading to an imbalancein ground water reserves, as the withdrawal of wateris more than recharging of water. This is leading todepletion of ground water resources resulting inincreasing depth of ground water table from surface.Though, according to recent studies by Assam StatePublic Health Engineering Department (PHED) afterthe current dry spell says that it have not affectedmuch the ground water table but in future chancesare there of major depletion of ground water table.However, time to time the scientists are givingwarnings to the people that ground water table isgoing down every passing year in the northeasterncities because of high extraction of ground water.Several urban settlements of the different states ofnortheastern region are already facing a severescarcity of potable water. In this backdrop, rainwaterharvesting appears to be the only solution that couldprovide some reprieve during the scorching summer.The principle itself is very simple-collectingrainwater during wet season and using it in times ofneed. Another part of the collected water could beused to recharge the aquifers and restore the waterlevel.

THE STUDY AREAThe North Eastern Region of India comprising

the states of Assam, Arunachal Pradesh, Meghalaya,Manipur, Mizoram, Tripura, and Nagaland, is a hugesprawling landmass made up of extensive countlesshills and mountainous terrain that rises in the northto snow-capped heights of the Himalaya, and is theplayground of the mighty river Brahmaputraregarded as one of the largest rivers of the worldand its tributaries (Fig:1). The climate of the regionmay be called Humid Mesothermal Brahmaputratype or ‘Cwb’ type according to Mr. W. Koppen. Itis humid sub-tropical, and high rainfall and highhumidity are the main features thereof. The numberof rainy days may sometimes equal three weeks in amonth (Table:1). The climate influences soil types.The soils of the region are alluvium derived and areclassified into old alluvial and forest soil. Soilprofiles representing major soil orders are Entisol,Inceptisol, and Alfisol. The region also encountersthe presence of poorly drenched soils. In addition,the mineralogy of soils, which includes sand, siltand clay mineralogy, is also equally important. Theaverage annual rainfall in the lower Brahmaputra

valley is 213 cm while the in the northeastern foothillbelt is 414 cm. The basin as a whole has the averageannual rainfall of 230 cm with a variability of 15-20 percent. The Himalayan sector receives 500 cmof rainfall per year, the lower ranges receiving morethan the higher area (Goswami, 1985). The principalrocks of Meghalaya plateau are granite and gneisses.At the foot of hills are found beds of conglomerates.In between these two ranges lies the narrowBrahmaputra valley, which is alluvial in origin andconsists of sand, sandstones, pebbles, clay andsometimes a mixture of sand and clay withdecomposed vegetable matter. The fragile rocks ofArunachal Pradesh are prone to severe erosion.

Fig: 1. North eastern Region :The study area

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WHY RAIN WATER HARVESTING ?PROBLEMS WITH GROUND WATER1) The current precious reserves of ground waterare vanishing rapidly due to heavy extraction ofground water, which is more than recharge. Hence,ground water is reducing in quantity.2) The other important factors for degrading thequality of ground water are heavy industrializationand contamination of surface & subsurface waterwith highly toxic pollutants. Already 21 districts ofAssam have reported arsenic contamination ofground water, while five of the districts havereported fluoride contamination.3) Unfortunately, we do not have system forprotecting water from contamination to stop orreduce the contamination, even to treat these groundwater reserves.

Considering all the above conditions andproblems of ground water, there must be somesolution for it. It is our duty to find out some definitestrategy on for solving the same; since we only havecreated the problem. Rainwater harvesting is thebest, economic and feasible solution for water crisisin comparison with other technologies, which arevery costly.

BAMBOO-THE GREEN GOLD ANDRAINWATER HARVESTING

Bamboo, a fast growing, versatile woody grassis found across the country. It is an economicresource having immense potential for improvingthe quality of life of rural and urban communitieswith environment regeneration qualities like carbonsequestering. Bamboo provides raw material forlarge industries like paper and pulp as well as forcottage and handicrafts industry (Fig. 2). Somebamboo species can grow one metre in a day.

Fig. 2 : Bamboo the Green Gold ofNorth East India

SUBSYSTEM COMPONENTS OFRAINWATER HARVESTING

A rainwater harvesting system consists of thefollowing subsystems: catchment area (roof),conveyance system (guttering, downspouts, firstflush and piping), filtration, storage and distribution.

Catchment Subsystem : For domestic rainwaterharvesting, the most common surface for collectionof water is the roof of the dwelling. Many othersurfaces can be used. Most dwellings, however, havea roof. Rainwater harvesting can be done with anyroofing material if it is for non-drinking use only.For potable use of rainwater, the best roof materialsare metal, clay, cementitious and thatch (from avariety of organic materials), provide a surfaceadequate for high quality water collection. InNortheast India, locally available grass thatched roofis very popular.Conveyance Subsystem : Guttering is used totransport rainwater from the roof to the storage

Table 1 : Annual Rainfall and Rainy days

State Rainfall & rainy days in a year

Assam 2262.95 mm with 144 rainy daysArunachal Pradesh 3000 mm with 200 rainy daysManipur, Mizoram & Nagaland 1927 mmMeghalaya 2050 mm with 200 rainy days

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vessel. Guttering comes in a wide variety of shapesand forms, ranging from the factory made PVC typeto home made guttering using bamboo (Fig:6) orfolded metal sheet. Guttering is usually fixed to thebuilding or bamboo hut just below the roof and itcatches the water as it falls from the roof. Somecommon gutter shapes and fixing methods are shownin fig.3.

Guttering could be installed on one grass roofthat had been constructed with a plastic membranebeneath it – this helps to prevent UV degradation ofthe plastic. The grass could be loosely thatched andfound locally. The plastic sheet guttering that wasinstalled is shown in Fig: 3. It should be designed tocapture all the water falling on the thatch and passingthrough to the plastic sheet. It should be fixed usingtwo long poles, one suspended below the eaves andone on top of the thatch. It can also be designed tobe demountable from the upper surface, such that itcan be ‘put away’ under the eaves when there is norain. Again, this helps prevent degradation due tosunlight.

First Flush System : Debris, dirt, dust and droppingswill collect on the roof of a building or other collectionarea. When the first rains arrive, this unwantedmatter will be washed into the tank. This will causecontamination of the water and the quality will bereduced. Many DRWH (Domestic Rain WaterHarvesting) systems therefore incorporate a systemfor diverting this ‘first flush’ water so that it doesnot enter the tank. There are a number of simplesystems that are commonly used and also a numberof other, slightly more complex, arrangements. Thesimpler ideas are based on a manually operatedarrangement whereby the inlet pipe is moved awayfrom the tank inlet and then replaced again once theinitial first flush has been diverted. This method hasobvious drawbacks in that there has to be a personpresent who will remember to move the pipe. Herewe have designed the storage tank with a sand filterfitted on the lid of the tank itself so that when thewater is diverted to the tank pipe it would filter thewater first then goes inside the tank (Fig: 5).

Filtration System : Again, there are wide varietiesof systems available for treating water before, duringand after storage. The level of sophistication alsovaries, from extremely high-tech to veryrudimentary. The sand-charcoal-stone filter is oftenused for filtering rainwater entering a tank. This typeof filter is only suitable, however, where the inflowis low to moderate, and will soon overflow if theinflow exceeds the rate at which the water canpercolate through the sand. Settling tanks andpartitions can be used to remove silt and othersuspended solids from the water. Many systemsfound in the field rely simply on a piece of cloth orfine mosquito mesh to act as the filter (and to preventmosquitoes entering the tank).

Storage Subsystem : In larger prospective of storagesystem we can say; Natural storage system i.e.recharging ground water aquifers & another is manmade that is storage tanks. They can be made ofvarious locally available materials, in various sizes& shape. In addition, their cost varies according tothat.DATA BASE AND METHODOLOGY FOR

Fig. 3 : Bamboo hut & Plastic sheet guttering and thedesigns of Gutters & Fixings

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NORTH EASTAverage annual rainfall was calculated from

the rainfall data collected from IndianMeteorological Department. For other related data,standard literature and methods have been followed.Methodology for rainwater harvesting are: forpotable water - simply to collect water from the roofto a storage tank or to collect water from roof torecharge bore well, open well, hand pump etc. Forgroundwater recharge abandoned well, abandonedor running bore well, hand pump, recharge pit,recharge trench or recharge well could be used. Toprevent surface runoff percolation ponds, checkdams, sub-surface dyke, recharge pit, recharge trenchcould be constructed. The low-cost water tank tostore rain water could be made of bamboo and plasticfilm. Villagers in North East use a large bamboobasket shaped like a silo, for storing grain. If thissilo is internally lined with a good grade polythenefilm, it can be used as a water tank. The bambooshould be made non-biodegradable by soaking it ina solution containing 450g of sodium dichromate,300g of copper sulphate and 150g of boric aciddissolved in 10litres of water. Such treated bamboohas an outside life of between 10 and 20 years.

The distance between adjacent bamboo poles

To prevent algae infestation, the tanks must be keptclosed without exposure to sunlight. Therefore,direct collection of rainwater is not safe for potableuse. The cost of a tank having a capacity of 1500litres is Rs.1000. If a larger tank is required, onecould make a plinth of cement and stones havingthe desired diameter, and by using chemically treatedbamboo poles, a palisade of bamboo is erected alongthe periphery of the plinth, like a fencing (Fig:4). Atank having a diameter and a height of 1.2m canstore 23,000 litres of water, which ensures a dailysupply of 60 – 80 litres of clean drinking waterthroughout the year. The cost of such a tank comesto about Rs.10,000. For ground water - recharge pitsare with size varying from 1.5 – 3.0 meter wide and2.0 – 3.0 meter deep could be constructed. It shouldbe lined with brick / stone with openings (weep -holes) at regular intervals. Top area of pit must becovered with grill.

The recharge point allows percolation and

Fig. 4 : Low Cost Bamboo Tank to Store Rain Water

should be about 50 – 60 cm. The plinth can have adiameter of up to 5 or 6m, but the height of thebamboo palisade should not exceed 120cm becausethe pressure exerted by the water column on the sidewalls is determined by the column height. Using thebamboo poles as a skeleton, the entire structure couldbe woven like wickerwork, using chemically treatedbamboo strips. One can use it to collect run-off waterfrom the roof, or one can even allow the rain to falldirectly into the tank. Once the tank is full its topmust be covered by another film of plastic, whichkeeps the water clean and prevents evaporation. Bothsunlight and nutrients are needed for algae to grow.

Fig. 5 : Simple design for rainwater harvesting, designfor low cost percolation pit for

ground water recharge and the design ofbamboo tank with a capacity of 23,000 lt. forplain and hilly areas of North-Eastern India.

DRAINOUT VALVE

OVER FLOW OUTLET

SLOW SAND FILTER FOR FILTERATION OF RAINWATER

OUTLET

1200

5000

BAMBOO WATER TANK OF CAPACITY 23000 lit

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recharges the groundwater. Recharge points couldbe of various dimensions, depending uponphysiographic and hydro geological conditions.Important considerations for successful rainwaterharvesting are:(i) location of recharge points,(ii) hydrological properties responsible forrecharging the aquifers, and(iii) Social responsibilities of the people.

The location of the recharge point especiallyin the crystalline terrain should have a weatheredmaterial with sufficient porosity to hold substantialquantities of water and also fractures for storage ofwater. Porosity, which generates the hydrologicalproperties, must be identified using groundwaterexploration techniques (well inventory, landscapeindicators, topographical features, geological set-up,structural controls, drainage conditions and geo-

electrical investigations). Therefore, the rechargepoints should be selected only after identifyingpermeable zone. If there is no permeable zone, thegroundwater cannot move from one place to otherand the water would come up through the rechargepoint and reach the surface. On the other hand, theingress of water through the permeable zone shouldbe checked, as the water reduces the shear andcompressive strengths of the material of thefoundation. It should be always kept in mind thatRainwater harvesting is a social responsibilityinvolving the whole community.

Tank size – ideal tank size vs. affordabilityTank sizing techniques usually only consider

the optimum size for a tank based on the rainfallavailable, the size of the catchment area (Table:2),and the demand on the system. Little considerationis usually given to the affordability of the tank. It isassumed that the person will be looking at capturingall the water from the roof or enough to meet alltheir demand.

In many cases, the person may not be able toafford a tank suitable for catching the optimumamount of water. In such cases, the tank size isdetermined by the tank cost and so, in this case, weneed to maximize capacity for a given (low) cost.Below, in Table: 3 we have classified domestic tanksizes into three distinct groups – small, medium andlarge scale.

Affordability is a strong function of tank size

Fig. 6 : Bamboo pipes to transfer water from the storedrainwater tank for ground water recharge

Table - 2 : Showing availability of rainwater in Thousand litres

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and tank design. The smaller the tank the cheaper itwill be and the cheaper the construction materialsand labour costs, the cheaper the tank will be. Forincreased affordability we are therefore looking atsmall-scale, locally produced RWH systems that uselocal materials like bamboo. Local manufacture anduse of local skills are design issues. Affordability isa function of a number of socio-economic factorsand is decided at the household level. Moreover,we know economies of scale show the cost per litredropping as tank size increases. In addition, factorymade tanks are generally more expensive thanlocally manufactured tanks.

Value of waterAs with many other goods, water has a

declining value with quantity. The first litre per dayis worth more than the tenth. By examining thelimited data available that relates householdconsumption per day to the effective unit cost of

water (i.e. cost per litre), we might construct a curvesuch as shown in Fig: 7. Each socio-economic groupwould have its own curve.

The cost line on Fig: 7 is horizontal, whichreasonably represents the situation where water isfetched, each successive litre requiring the sameinput of labour. Such a line does not fairly representharvested roof water, where the effective costgeneral rises with daily consumption despite theeconomies of scale in tank construction. A typicalcost vs volume characteristic for Rain WaterHarvesting supply is shown in Fig 7.

Sometimes we find examples of water purchaseand use them to infer the value of water. Richerhouse holds, or those experiencing illness, may payfor water to be brought to the house. More usually,we have to infer costs indirectly through conversionof fetching distance/height into time and then timeinto money. Such costs, like the value of waterdiscussed above, will be lower for poorer householdsthan for richer ones.

Some careful steps to be taken beforeimplementation of rain water harvesting projects• Convenient first flush device must be integrated.• a good fitting, light-proof cover will prevent debris,animals or humans from entering the tank andprevent light from causing algae growth• water quality can enhanced by putting water intothe tank and taking it out of the tank at the correctlocation – low-level tank entry and floating off-takesare devices designed to aid this approach• good sanitary conditions around a tank will prevent

Table 3 : Tank scale classification

Scale of Descriptiondomestictanks

Small-scale Any tank or jar up to seven days storageor up to 1000 litres

Medium A tank up to several weeks storage orbetween 1000 and 20,000 litres storage

Large Any tank with several months ofstorage or above 20,000 litres storagecapacity

Fig. 7 : Showing value vs quantity and cost vs volume

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disease being spread• water extraction should be such that the water isnot contaminated while being drawn

Poorly managed water harvesting systems maycause soil erosion and soil instability. Therefore,water-harvesting catchments require maintenance tokeep them in good condition.

CONCLUSIONSThe forest covers are decreasing. Hence, water

and soil hold by roots, plants are degraded. And, itis affecting hydrological cycle badly. This isresulting in tremendous increase in depth of groundwater level. It is high time to implement rainwater-harvesting projects in northeastern part of India.These technologies are simple to install and operate.Local people can be easily trained to implement suchtechnologies, and construction materials are alsoreadily available. It is convenient in the sense that itprovides water at the point of consumption, andfamily members have full control of their ownsystems, which greatly reduces operation andmaintenance problems. Although regional or otherlocal factors can modify the local climaticconditions, rainwater can be a continuous source ofwater supply for both the rural and poor.

The feasibility of rainwater harvesting in aparticular locality is highly dependent upon theamount and intensity of rainfall. Other variables,such as catchment area and type of catchmentsurface, usually can be adjusted according tohousehold needs. As rainfall is usually unevenlydistributed throughout the year, rainwater collectionmethods can serve as only supplementary sourcesof household water. Rainwater harvesting appearsto be one of the most promising alternatives forsupplying freshwater in the face of increasing waterscarcity and escalating demand in the urban as wellas in the rural areas. The pressures on rural watersupplies, greater environmental impacts associatedwith new projects, and increased opposition fromNGOs to the development of new surface watersources, as well as deteriorating water quality insurface reservoirs already constructed, constrain theability of communities to meet the demand forfreshwater from traditional sources, and present anopportunity for augmentation of water supplies usingthis technology. May be with every rural and urbanhousehold participation in their unique small scalerainwater harvesting projects replenishes the

groundwater reserves because it is the only presentstate-of-art to replenishes the ground water tablewhich would enable our dug wells and bore wellsto yield in a sustained manner. A sustainable humancommunity should use its resources withoutendangering the survival of future generations.

ACKNOWLEDGEMENTThe authors gratefully acknowledges thanks to

Prof. J.N.Sarma, Dept. of Applied Geology,Dibrugarh University, Dibrugarh, Assam for hisvaluable suggestion. Thanks to our friend NegulDevan K.R. (B.E) for timely help.

REFERENCESC-3 Report by IIT Delhi, July 2000, Water quality in domesticroof water harvesting systems (DRWH) & Bamboo reinforcedconcrete constructionGould, J.E. 1992. Rainwater Catchment Systems for HouseholdWater Supply, Environmental Sanitation Reviews, No. 32,ENSIC, Asian Institute of Technology, Bangkok.Gould, J.E. and H.J. McPherson 1987. Bacteriological Qualityof Rainwater in Roof and Groundwater Catchment Systems inBotswana, Water International, 12:135-138.Nissen-Petersen, E. 1982. Rain Catchment and Water Supplyin Rural Africa: A Manual. Hodder and Stoughton, Ltd., London.Pacey, A. and A. Cullis 1989. Rainwater Harvesting: TheCollection of Rainfall and Runoff in Rural Areas, WBC PrintLtd., London.Rao, N.S, “Important considerations for the success of rainwaterharvesting” Hydrogeology Laboratory, Department of Geology,Andhra University,Rees, D.G, Nyakaana, S & Thomas, T.H, 2000, DevelopmentTechnology Unit ,School of Engineering, University of Warwick,Domestic Rainwater Harvesting Research Programme “VERY-LOW-COST ROOFWATER HARVESTING IN EASTAFRICA” (Based on a Feasibility Study performed in the GreatLakes Region during May – July 2000) by Working Paper No.55, pp. 8,9, 22,23,30,31.Schiller, E.J. and B. G. Latham 1987. A Comparison ofCommonly Used Hydrologic Design Methods for RainwaterCollectors, Water Resources Development, 3.Singh, V.P, Sharma, N & Ojha, C.S.P 2004, Ed. TheBrahmaputra Basin Water Resources, Vol. 47, Kluwer AcademicPublishers, London.Singh, R.V. 2003, Ed. Watershed Planning and Management,Yash Publishing House, Bikaner-334003, India.UNEP (United Nations Environment Programme) 1982. Rainand Storm water Harvesting in Rural Areas, TycoolyInternational Publishing Ltd., Dublin.Wall, B.H. and R.L. McCown 1989. Designing Roof CatchmentWater Supply Systems Using Water Budgeting Methods, WaterResources Development, 5:11-18.

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*SE, ME, MIE, PG (PMIR), DIRECTOR (LIAISON), HQ EAC IAF, C/O 99 APO

ABSTRACTA precious source of water availability has become scarce, hence the need for

conservation. The development of water resources in the country is at cross roads. Thissustainability of water resources has been endangered by vagaries of rainfall and unplanneddevelopment. An optimum development can be achieved by the conjuctive use of surface andground waters.

Rain water Harvesting is the concept, which includes a holistic approach to develop,augments, protect and conserve water resources. This concept is to be envisaged and practicein order to ensure the sustainability of ongoing groundwater development for multiple usesand to provide scope for further development of growing demand/population. To maintainthe ground water resources indefinitely, a hydrologic equilibrium must exist between all waterentering and leaving the water basin of the earth. Rain water Harvesting i.e Artificial Rechargeof the ground water resources is the most commonly adopted and cost effective method ofreplenishing the ground water reserves.

The Rain Water Harvesting are based on the different technique. The methodssuggested for Rain Water Harvesting is water spreading, recharge through pils, trenches,wells, shafts and directly run off water into the existing wells. The choice/selection of anyparticular method is governed by local hydrogeological, soil condition etc and ultimate use.

Rain water Harvesting needs to be implemented to avoid the paucity of water resourcesfor present/future demands. Since the nature has showered enough potential to recharge ourexisting water bodies and also to conserve/preserve the waters for future needs/requirements.

1.0. INTRODUCTIONA precious source of water availability has

become scarce, hence the need for conservation. Thedevelopment of water resources in the country is atcross roads. This sustainability of water resourceshas been endangered by vagaries of rainfall andunplanned development. An optimum developmentcan be achieved by the conjuctive use of surfaceand ground waters.

Rain water Harvesting is the concept, whichincludes a holistic approach to develop, augment,protect and conserve water resources. This conceptis to be envisaged and practice in order to ensurethe sustainability of ongoing groundwaterdevelopment for multiple uses and to provide scopefor further development of growing demand/

population. To maintain the ground water resourcesindefinitely, a hydrologic equilibrium must existbetween all water entering and leaving the waterbasin of the earth. Rain Water Harvesting i.eArtificial Recharge of the ground water resources isthe most commonly adopted and cost effectivemethod of replenishing the ground water reserves.

Army cantonments to a large scale depend onsupply of water from civil bodies. And since theentire country is in high water stress situation, thetotal available water resources for various use sectorshave decreased drastically. This has resulted inmeager an erratic water supply to cantt therebyencouraging exploitation of ground and surfacewater available within the cantt by the MES. With aview to conserve the already depleting reservoirs,


23. Rain Water Harvesting

*Shri S. K. Sinha

146

judicious management of water in each cantt shallbe undertaken. In this paper the varioustechnological aspect of Rain Water Harvesting hasbeen described with basic theory and with realground conditions.

2.0 AIMThe aim of the Rain Water Harvesting by virtue

of suitable techniques/methods to conserve thealready depleting reservoirs. Therefore, the localunits/area/body are impressed upon to under takethese feasible technique/methods through simple butlucid description, provide small budgetary estimateswith time frame in which this can be achieved.Therefore, our aim is to improve the existing groundsurface water through efficient rainwater harvestingmanagement.

3.0 MANAGEMENTIt is the technical methods, which manage the

existing surface, and ground water potential of thecatchments or water shed areas. So as to develop,augment and conserve them. Judicious harvestingmanagement is most inevitable to the followings:-3.1 Arrest ground water decline, improve groundwater levels and availability.3.2 Beneficiate water quality in acquirers.3.3 Arrest seawater ingress.3.4 Conserve surface water run off duringmonsoons.3.5 Enhance availability of ground water at thespecific place and time.3.6 Reduce power consumption.3.7 Consume unused wastewater.3.8 Conserve energy.3.9 Save environment from degradation.

4.0 ADVANTAGE OF RAIN WATERHARVESTING4.1 Enhanced sustainability of water supplyprojects and structures;4.2 Improved well yields and reduced pumping liftsand cost;4.3 Improved water quality through dilutionespecially fluoride, nitrate and salinity. This isachieved with filtration and percolation.4.4 Conservation of water lost to run off andevaporation.

4.4 Reduces flood hazard and soil erosion.4.5 Treated urban effluent can be recharge andquality beneficiated by re-circulation through theaquifers.

5.0 SUGGESTED METHODS /TECHNIQUES

Methods for local unit / area / body can beimplemented in diverse hydro geological and variedclimatic set-ups. Number of methods are availableto achieve the sustainability of water through rainwater Harvesting. The best method among theavailable methods depends on hydrology, availableof source of water, available of land andphysiography of the areas. The methods/techniquesare broadly categorized are as under :5.1 RECHARGE ON SURFACE

This includes the following :-5.1.1 Loading.5.1.2 Basins or percolation tanks.5.1.3 Stream augmentation.5.1.4 Ditch and furrow.5.1.5 Over irrigation.5.1.6 Revival of village pond concept.5.1.7 Recharge of secondary treated urban liquideffluents in identified aquifers.

5.2 DIRECT RECHARGE IN SUBSURFACE AQUIFERS

This includes the following :- Injection wellsare recharge well. In this the recharging in watershedis carried out by directing discharge of rainwaterthrough a settling sump to the underground waterbed.These wells can be used both as percolation wellsand recharge wells. The advantages of directinjection of rooftop run off water in the wells are :-5.2.1 Harvesting from roof rain water.5.2.2 Relatively high rate of recharge.5.2.3 Utilisation of ground water during non rainydays.

5.3 OPEN WELL RECHARGEDirect recharge of the aquifer through open

wells will be an easier and in expensive process inthe shallow aquifer region. The rooftop run off watercan be directed in to the open wells through pipesand settling pit to avoid possible turbidity.

5.4 RECHARGE PITS AND SHAFTS

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TRENCHES5.4.1 Recharge pits. Pits are dug depending uponavailable rooftop water from the buildings and arelocated inside the premise and away from foundationor concrete structures so as to have its sitting overpervious soil for better and faster absorption. Thepits are preferably located near the precinct andthereafter filled with permeable material likepebbles, gravel and sand for better percolation andimproved water quality through dilution duringpercolation.

5.4.2 Recharge shaft. Where the contour andtopology of a large area permit flow in unidirectionaland having step slopes, the shafts are dug. Theaverage depth of 10 to 15 meters with width of 1meter and length of 2 meters at places dependingupon amount of water available from catchments.These are terminated above the aquifer level. Theshafts are usually cased with PVC casing to preventcontamination and collapse. These are back filledwith pervious soils, which facilities faster andefficient percolation and mitigates bio and chemicalpollutions after filtration through the soil.

5.5 BORE HOLE FLOODING

5.6 NATURAL OPENINGS AND CAVITYFILLINGS

Normally the topology of cantt is such thatthese openings are limited.

5.7 COMBINATION OF SURFACE ANDSUB SURFACE5.7.1 Following are the techniques usuallyadopted Basin/percolation tanks with pits/shaft orwells are constructed to collect subsurface andsurface water.5.7.2 Water treatment : In this technique theaffluent/sewage/sullage is collected in a pit,filtered and then supplied to required placethrough gravity well or deep trenches in slope.

5.8 In this method induce recharge from surfacewater source is utilised for improving ground waterpotential. Another practice is to have aquifermodification.

5.9 GROUND WATER RECHARGE OF

EXISTING WELLSGround water recharge of existing bore wells

is one of the method of modifying the hydrologicalcycle and thereby providing ground water in excessof that available by natural processes. It isaccomplished by augmenting the natural infiltrationof precipitation or surface water in to undergroundformations by some method of construction, byproviding or spreading of water or by artificiallychanging the natural conditions.

6.0 INDICATION OF DEPLETING WATERYIELD

It has been observed from the postperformances of the bore wells/shallow wells/openwells that the over exploitation has graduallydiminished their yields. This was ascertain / evidentfrom the observation and are as under.6.1 Poor quality of water, occasionally muddy.6.2 Frequent lowering of submersible pump inorder to keep the later submerged.6.3 Water output varying and found in spurts.6.4 More draw out than natural recharge by rainsetc. Bore wells being run continuously for hourswithout permitting recharge.6.5 Sealing of natural recharge areas in and aroundbore wells with imperviousside well, streets, parking lots and buildings. Thisdiverts ground water flowdirection and prevent recharge.6.6 In real ground situation, sub surface water isdiverted due to troughs andmounds, other Geological, Topological conditions.

The above factors have caused overdraft fromthe bore wells and must be rechargedimmediately as the yield from these bore wells havebeen helping us to reduce dependenceon outside agency for the deficient supply of waterespecially during peak summer whenthe catchments go dry and reduce available water.

The wells which are near surface water bodies(such as ponds, Golf course, Dairy form and playgrounds) continuing to give good yields andharvesting is naturally carried out.

7.0 COMPUTATION AND TOTALPOTENTIAL OF RECHARGE

The potential through bore well harvesting willdepend upon how big catchments is diverted for

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percolation near bore wells, through trench/pit/shaft.The exact quantity is difficult to assess.

7.1 RECHARGEExact computation of sub surface inflow and

infiltration (Water entering the soil at the surface iscalled infiltration) need comprehensive geologicalinvestigation. The recharge of bore wells can becarried out through water shed approach while driedup dug well can be used directly for storing water ofsurround catchment.

The rainwater harvesting to increase the watertable should be graded so as to prevent theaccumulation or retention of surface water within aradius of 15 meters from the bore well.

An expensive proposition is not viable forMilitary stations where water quality can beimproved with silt filtering pit alone. Hence it isbeing considered only at those locations to augmentfor potable water. The shallow wells were rainwaterfrom surrounding catchments can be directed insidethrough silt filtering unit above as the water is softand does not get surface impurities.

To have economical and viable harvesting ofrainwater in the water source, an area of approx5,000 to 10,000 Sq m around bore well should bemade ground water collection. The area shouldcommence 15 meters away from bore well.

Total water collection/recharge per bore wellAverage rainfall (Say) = 780 mmAvailable for harvesting = 390 mm

(@ 50%) after evaporation To harvest 10% of above= 39 mm (0.039 M)Total water recharge for = 10,000 x 0.039 M10,000 Sq M = 3,90,000 Liters

This water is available in one year (90 days ofrains) per bore well assuming unpaved area aroundbore well.

7.2 ROOFS HARVESTINGThe collection and storage of rain from rooftop

run off has been practiced by man since ancienttimes. This may be particularly useful for domesticuse in the residential, messes and offices. Thecollection of rain water from paved or GI corrugatedroofs and court yards of houses is done either instorage tank or in ground water reservoir.

METHODThe water is led from the roof to the storage

tank through a series of gutters and pipes.Conventional gutters are normally used, but foreconomy they can be made with “V” shaped lengthsof tin sheet hang under the roof edge from wire orlengths of rigid PVC pipe at along the length andclamped to the edge of the roof. Rigid PVC pipesare considered as they are cheaper easier to maintainand will reduce contamination.

8.0 DESIGN OF TRENCHES AND PITS8.1 TRENCHESAverage rainfall = 780 mmAvailable for harvesting = 390 mm (50% ofaverage)

To be harvested in the water = 39 mm 10% availableeconomically harvesting

Economic width & Depth of trench = 1.5 M depth& 0.5 M Width

For 1000 M2 roof top available water= 1000 X 0.039 M3 = 39 M3

Assuming 90 days rainfall per= 39M3 per rain fall rainfall average water

90 = 433 litter per day of rainPVC rigid pipe for 40mm can carry water to

the required place.

8.2 SIZE OF PITAverage Rains yield = 3.05 M3 per showerTaking 100% extra for proper storage and

percolation without contamination by surface water.

Size of pit = 6 Cu MTaking 2 M Dia Pit Depthof pit (L) = 6 X 4

pX 4

= 6p

= 1.91MSay 1.9 M depth

Such pit can be easily & economically dug

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without encountering hard rock with mechanicalexcavator if required.Size of Pit = 6 Cum (Dia – 2.0M, Depth – 1.9M)15% of sand = 0.15 X 6 Cum20% of 20 mm = 0.20 X 6 Cum aggregate50% of 40 mm = 0.50 X 6 Cum aggregate

9.0 EXPLOITATION AND HARNESSINGTOTAL POTENTIAL OF WATERHARVESTING

Considering a defence land / area available forwater shed is 9000 acres.

Area / land = 9000 acres1 acres = 4047 SQMTotal SQM land = 36423000 SQMAverage rainfalls (Say) = 780 mm (0.780M)Available for recharge after evaporation from soil& water surface (evaporation & percolation losses)

= 390 mm (0.390 M)Total potential = 0.39 X 36423000 M3

= 14.20 Millions KL

This indicates that the total potential of waterharvest in one rainy season if exploited is sufficientto meet the requirement to the maximum/ full extent.

This potential can be tapped from rooftop (mostefficient use), road top (difficult to tap due to faultyslopes, berms and economics) and from water shed(catchment) through soils other than paved and rooftop.

9.1 METHODSArtificial charge of water source can be

managed and developed by planned extractions ofground and surface water during periods of lowprecipitation while subsequent replenishment can bemade during periods of surplus surface supply. Sucha coordinated operation of surface and ground watersupplies is possible if there is sufficient ground waterstorage to meet the requirements for regulation oflocal water supplies and if the aquifers possessessufficient transmissibility to permit the movementof recharged water to the area of extraction. Therecharged storage constructed under watershedapproach should be devoid of losses due toevaporation and quality deterioration due topollution (which will make it useless for anyapplication).

Method 5.1 for Recharge on surface are mostsuitable for water harvest.

10.0 PREFERABLE LOCATIONS TO DO IT10.1 Cantt/Military Stations/Areas can besubdivided into smaller catchments /water shed and maintained under local units. Thesewatersheds can be.10.1.1 Ranges.10.1.2 Training areas10.1.3 Play fields10.1.4 Open spaces and parks

These above areas are normally situated atdifferent locations in Defence establishment.Therefore method for smaller catchments area ismore suitable and viable. The methods for smallercatchments area are as under.

10.2 METHODS FOR SMALLER AREAHARVESTINGAssuming the followingsRange Area = 500 AcresTraining area (10 Pockets) = 1000 Acres (Total)Play fields (5 Pockets) = 50 Acres (Total)Open Spaces (40 Pockets) = 200 Acres (Total)

10.2.1 Check Dams :Ranges can be utilised for creating check dams

at low laying area and storing water. The check dammay be ailed with cheaper option to prevent fall ofhuman being and animals.

The range area = 500 Acres= 2023500 (1 Acre = 4047 SQM) SQM

With 390 MM of rainfall available for harvesting.Total water available from rains

= 2023500 x 0.39 Cu M= 789165 Cu M

To harness 10% of this water check dams ofsizes 30m x 1mx1m may be constructed in naturalslope directions 3 CHECK DAMS will beeconomically viable to cover the area.

10.2.2 STAGGERED CONTOUR TRENCHES(SCT) / PERCOLATION TRENCHES (PT)

The training areas can be utilised for creatingstaggered contour trenches (SCT) and percolationtrenches (PT). In general, the training areas are

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scattered in defence establishedThe training area is 1000 acres (Say) in

Military/Cantt Station/Areas. Considering there are10 Nos of pockets for training in various units.

Total water potential in 100 acres= 100 (Acres) x 4047 SqM= 100 x 4047 x 0.39 M3= 157833 M3

The staggered contour trenches (SCT) ofdimension 3.0M x 1.0M x 1.0M (For average 20000M3 of water potential area) can be created. Theseare to be created at the end of slope and properlyprotected to prevent accidental of human/others.

The No of SCT= Nos of Pockets x Water Potential in M3

20000

= 10 x 157833 = 78.92 20000

= 79 NosTherefore, in each pocket 7 or 8 Nos of SCT

may be created.

Percolation Trenches (PT) may be dug awayfrom the training tools and located at fenced places.Percolation trench may be located at the downstream. The trench may be size 1m x 1m and allalong the low stream at least 50 M and filled withimpervious materials locally available and notspecified provided for their purpose. Total trenchlength on four sides 50m (10) location = 500 RMof 1m x 1m.

10.2.3 PLAYFIELDS, OPEN SPEACES ANDPARKS

The play fields, open space and parks areas canbe effectively utilised for rain water harvesting.

Play fields : Considering 5 pockets with total 50acres of play field in Defence Establishment have atotal water potential of 86808 CUM. A lot of carehas to be taken to create water-harvesting structuressince play fields are common places for playactivities, leisure walk and other activities. The playfields have natural slope duly leveled. This water

from all sides can be collected and allowed to drainaway from sports fields to a location where storagecan be made. Trenches dug should be covered withmanhole cover arrangements.Average play field in Cantt Area= 10 Acres for each pocket.Total water potential from rain= 10 x 4047 x 0.39 M3= 15783M3

To harvest 10% of it, trenches may be dug allround of size 0.5m x 0.5 m with manhole cover. Thetrench size is sufficient to carry per day rains water.Which is received in 90 to 100 days of rainfalls.

The above proposal is however very expensivebut will fetch a great deal of water.Total trench length= 1000 RM for on average 10 acres field.

Total excavation Per site = 1000 x 0.5 x 0.5= 250 CuM

For 5 play field site = 250 x 5 CuM= 1250 CuM

Manhole cover of 1 m x 0.6 m each = 1000 No x 5 = 50000 Nos for sites

OPEN SPACES AND PARKS : At these placescreation of ponds, tanks and shaft storage at deeplow lying can be considered.Total open spaces at 40 pockets in station =200 AcresAverage Area = 05 acresWater potential = 7891 CUM

Trenches of size 0.5 x 0.5 m can be dug to carryrainwater to the storage spaces created in the formof tank/ponds. These structures may be properlyfenced and treated with bleaching powderperiodically approx 50 RM of trench 0.5 x 0.5 M tocarry water to 40 different storage can be considered.

Cu M of trench = 50 x 40 x 0.5 x 0.5= 500 CUM

Pond size can be 10 m dia at 40 locations withaverage 1 m depth properly fenced on all sides.

Note : The capacity of ponds created is of much smallersize than the water potential available for harvesting.This is kept to keep economic viability of these structuresin the available space without hampering training/playactivities. The depth has been kept as 1 M maximum sothat if required the same can be achieved through troopslabour.

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11.0 DRAWINGSThe drawings showing composite plan for

recharging structure, design details of Ferro cementstorage tank capacity 12000 Ltr, plan for rechargingstructure, design and details of recharging structure,typical drawing details of roof water harvestingstructure, roof top rain water harvesting structureand design of pits for rain water harvesting areattached as

COMPOSITE PLAN FOR RECHARGE STRUCTURE NO.1

Fig – 1, Composite Plan.Fig - 2 ,Plan of Recharging.Fig – 3.1, Typical Drawing Details.Fig – 3.2, Typical Roof Top HarvestingFig – 3.3, Design of Storage Tank and ilters.Fig - 3.4, Type of PercolationFig – 4 and Details of Recharge StructureFig – 5 Design of Pit

For understanding and execution of works.

Fig – 1 : Composite Plan

152

Fig - 2 : Plan of Recharging

153

Plan for Recharge Structure No.2

3.0 m

3.0 m

Inlet Pipe

6” dia pipe

Plan for Recharge Structure No.1

3.0 m

3.0 m

Inlet Pipe

6” dia pipe

TYPICAL DRAWING DETAILSROOF WATER HARVESTING STRUCTURE

Fig – 3.1 : Typical Drawing Details

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TYPICAL ROOF TOP RAINWATERHARVESTING SYSTEM

Fig – 3.2 Typical Roof Top Harvesting

FILTERS USED FOR FILTERINGRAIN WATER

DESIGN DETAILS OF FERRO CEMENTSTORAGE TANK 12,000 Liters capacity

Fig – 3.3 Design of Storage Tank and ilters

155

Fig - 3.4 : Type of Percolation

156

Fig – 4 : Details of Recharge Structure

157

Fig – 5 : Design of Pit

12.0 CONTAMINATIONMedical Authorities of civil area/SHO for

Military station may object to open harvesting ofwater, since the harvesting surfaces being exposedthrough out the year and are subject to contaminationby dust, insects and birds and those at ground levelare also liable to be contaminated by animals andhumans. The following precautionary measures arerecommended:- Location from Contaminationsource Recommended distance of harvestingstructure such as pit, trenches etc. from source ofcontamination.Building sewer 15 MSeptic tanks Disposal filed 15 MSeepage pit 30 MSwimming pool 45 M

If any bore well or shallow well is to be chargedwith water, which is at a distance less than above,should permit deeper trenches with silt-settingchamber following by silt-filtering pit. The bore

well water may contain faecal strap-to-coccid andshould be used only for conservancy unlessotherwise tested.12.1 The trenches/pit so dug should be properlyfenced and kept clean. The first flush ofthe new rains should be run to waste.12.2 The storage tanks below ground should be fullyenclosed to prevent evaporation.12.3 All aperatures shall be screened to prevent theaccess to mosquitoes, rodents, lizardsand other life etc.

13.0 CONCLUSIONRain Water Harvesting needs to be

implemented in defence area/other places in orderthat the on going actives are not hampered due topaucity of water resources. Nature has showeredenough potential to recharge our existing waterbodies and also to store water for years to come andto meet the present/future demands.

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INTRODUCTIONWe have greatly hampered the natural ground

water recharge by drawnif excessive water andcovering / paving up all the available open land.Rainwater harvesting is merely “putting backrainwater into the soil or in underground or aboveground tank so that we can draw it whenever weneed it”. Less than 1% of world‘s water is availablein the form of river, pond and lake for human use.Out of total rainfall in India, run off is about 85 %,percolation is about 7%, evaporation is about 5%and human use is about is about 3%. Urbanizationand increase in population in the recent decadeshave contaminated water bodies, thus making themunfit for drinking and use. This is coupled withman’s growing needs and excessive tapping ofgroundwater through numerous bore wells and tubewells, which has depleted water table to great extent.Rain Water harvesting (RWH) will to some extendhelp to meet the increased demand. It has beenestimated that the amount of rainwater that falls onthe terrace of the houses can take care of the waterrequirement of an average family of four membersfor one year. RWH is a technology used for collecting andstoring rainwater from rooftops, the land surface orrock catchments using simple techniques such asunderground check dams. RWH has gained tremendous interest amongacademicians, institutions and layman in the pastfew years. Roof top harvesting has a clearerdefinition as water collected from rooftop chieflyfor domestic consumption. Rain Water Harvestingis a low cost solution to solve water crises.

Need of RWH :In India there are 600000 villages and almost

70 % of population is rural and agriculture related.The rainfall pattern in India is highly irregular inspace and time. Most of it is concentrated duringjust a few months of year and that too, in a fewregions. Rainfall occurs about 70 % in about fourmonths. So, even in a year of normal rainfall, someparts of a country face several droughts. RWHsystem benefits in many ways in rural and urbanareas such as it develop improvements in infiltrationand reduction in runoff, improvement ingroundwater quality, reduces strain on speciallyvillage Panchayat / Municipal/Municipalcorporation water supply, improvement ingroundwater level and Yields etc.

Advantages and Disadvantages :Advantages:1) It gives high agriculture returns.2) It is a potential solution to problems of ruralpoverty and unemployments, resulting in an overallimprovement in the nation’s economy.3) Local people can be easily trained toimplement such technology and constructionmethods. RWH is a convenient in the sense that itprovides water at the point of consumption, whichgreatly reduces the operation and maintenanceproblem.4) It is sustainable due to decentralization andcommunity participation.

Disadvantages :This system mainly depends upon the limited

supply and uncertainty of rainfall. Adoption of thistechnology requires a bottom up approach ratherthan top to bottom. This makes this system lessattractive to some government agencies. If old roofis used as the catchment area, if it is under tree

24. Review of Rain Water Harvesting in India

*R. M. Dhoble **Dr. A. G. Bhole

*Sr. Lecturer,Civil Engg.Dept., G.H.Raisoni College of Engineering, Nagpur.**Retired Prof.Civil Engg.Dept., V.N.I.T. Nagpur


159

branches, if the building relies on wood heat, or ifthe air is too polluted, then there may be possibilityof contamination of rain water.

COMPONENTS OF RWH SYSTEMIt consists of various stages, transporting

rainwater through pipes or drains, filtration andstorage in tanks for reuse or recharge. The commoncomponents of RWH system consists of three stagesA) CATCHMENTS : The catchments of RWHsystem, the surfaces which directly receive therainfall and provide water for system. It can be pavedarea like a terrace or courtyard of building or anunpaved area like a lawn or open ground. R.C.C.,galvanized iron or corrugated sheets can also be usedfor R.W.H. Following Fig. shows elements of rainwater system.

As the rooftop is the main catchment area, theamount and quality of rainwater collected dependsupon the area of catchment, intensity of rainfall andtype of roofing materials. Galvanized corrugatediron, asbestos cement sheets and slate and tiles cancollect reasonably pure water from the rooftops.Although thatched roof tiled with bamboo gutter,laid in proper slopes can produced almost the sameamount of runoff less expensively (Gould, 1992).Because of possible health hazards, bamboo roofsare least suitable and roofs with metallic paints orother coating are not recommended as they mayimpart taste or colour to the collected water. To avoidentry of dust, leaves and bird dropping, the roofcatchment should be cleaned regularly.

Gutter : Channels are provided all around the edgeof sloping roof to collect and transport rainwater tothe storage tank. It semicircular or rectangular andcould be made using• Locally available materials such as plaingalvanized iron sheet (20 to 22 gauge), folded tothe required shapes.• Semicircular gutter of PVC material can bereadily prepared by cutting those pipes into twoequal semicircular channels.• Bamboo or betel trunks cut vertically in half.The size of gutter should be accurate to flow waterduring highest intensity of rainfall and it is advisableto make them 10 to 15 % over size. Gutter need tobe supported so they do not sag or fall off whenloaded with water. The way, in which the guttersare fixed depending upon the construction of houseshaving wider eaves, some method of attachment tothe rafter is necessary.

Conduit : Theses are the pipelines or drains thatcarry rainwater from the catchments or rooftop areato the harvesting system called as down conductcan be of any materials that are commonly available. The following Table No 1.0 gives ideas about thediameter of pipe required for draining out rainfallbased on rainfall intensity and roof area. The down-pipe should be atleast 100 mm diameter with 850-micron wire screen at the inlet to prevent dry leavesand derbies from entering into pipe.

Source – A water-harvesting manual for Urban areaFig. 1

and on the mouth of inlet of drained pipe, mesh of850 micron screen or coarse mesh 10mm x10mmshould be provided to prevent the entry of derbiesas shown in Fig No 2. The inlet of drained pipeshould be provided on the sloping side of the roof.

Course mesh – It should be provided at the roof toprevent the passage of derbies. It should be providedat the bottom of parapet wall as shown in figure

Source: A water Harvesting manual for urban areaCourse mesh on roof top (Fig 2.0)

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First flushing - First flushing device is the valvethat insures that runoff from the first spell of therain is flushed out and does not enter the system.This needs to be done since the first spell of raincarries a relatively large amount of pollutants fromair and the catchments surface. There are severalpossible choices to collect clean water for thestorage tanks. The most common is the down- pipeflap. With this flap it is possible to direct the firstflush of water flow through the down pipe, whilelater rainfall is diverted to the storage tank. When itstarts to rain, the flap is left in closed position,directing water to the down-pipe, and later, openedwhen relatively clean water can be collected(Refer Fig. No 3). A great disadvantage of usingthis type conveyance control system is necessarilyto observe the runoff quality and manually operatethe flap. An alternative approach would be toautomate the opening of the flap.

A funnel shaped insert is integrated in to thedown-pipe system. Because the upper edge of thefunnel is not direct contact with the sides of down-pipe, and a small gap exist between the down-pipewalls and the funnel. When the rain starts, thevolume of water passing down the pipe is very smalland the contaminated water runs down the pipe,around the funnel and discharged directly to therecharged structure if available or over the ground.When the rainfall continues the volume of waterincreases and the clean and fresh water carried tothe storage tank. The pipe used for collection of

rainwater, is generally made up of PVC or otherinert substance to avoid corrosion of pipe due tothe pH of rainwater can be low.

Table No 1.0 Size of rainwater pipe for roof drainage

Diameter Average rate of rainfall in mm/hourof pipe(mm)

50 75 100 125 150 20050 13.4 8.9 6.6 5.3 4.4 3.365 24.1 16.0 12.0 9.0 8.0 6.075 40.8 27.0 20.4 16.3 13.6 10.2100 85.4 57.0 42.7 34.2 28.5 21.3125 - - 80.5 64.3 53.5 40.0150 - - - - 83.6 62.7

mm/ h – milliliter per hour Source – National Building Code.

Source: A water harvesting manual for urban areasmanual for urban areas

First flushing arrangementFig. No 3

B)FILTER : The filter is used to remove suspendedpollutants from rainwater collected over the roof. Afilter unit is a chamber filled with filtering mediasuch as fiber, course sand and gravel layer, to removethe debris and dirt from water from before it entersthe storage tank or recharge structure. Charcoal canbe added for additional filtration. (Refer fig. No. 4)

Source: A water harvesting manual for urban areasSand filterFig. No 4

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b) Dewas Filter : Most residents in Dewas inMadhya Pradesh, have wells in their houses.Formerly all that wells would do was exactgroundwater but then, the district administrative ofDewas initiated the ground water recharge scheme.The rooftop water was collected and allowed to passthrough fitter system called Dewas filter designedbyMohan Rao, District collector of Dewas. The waterthus filtered is put into the small service tube well.

The filter consist of Polyvinyl chloride (PVC)140 mm diameter and 1.2 m. long there are threechambers .the first purification chamber has pebblesvarying between 2-6 mm and second chamber hasslightly larger pebbles between 6-12 mm and thirdchamber has largest 12-20mm pebbles. There ismesh at the outflow side through which clean waterflow out after passing through three chambers.(Refer fig. No. 6)

d) Varun: S. Viswanath developed a filter named‘Varun’ for purifying rainwater. According to him,from a decently clean roof ‘Varun’ can handled50mm/hour intensity of rainfall from 50 sq. m. of aroof area. This means the product is relativelystandardized. Varun is made from 90-liter highdensity Poly Ethylene (HDPE) drum. The lid istumbuer and holes are punched in it. This is the firstsieve, which keeps out larger leaves, twinges etc.rainwater coming out sieve then passes through the

a) Sand Filter: Sand filter s have commonly availablesand as a filter media. Sand filters are easy andinexpensive to construct. These filters can beemployed for treatment of water to effectivelyremove turbidity, colour and microorganisms. Insimple sand filter that can be constructeddomestically, the top layer comprises course sandfollowed by 5-10 mm layer of gravel followed byanother 5-25 cm layer of gravel and boulder.(Refer fig. No. 5)

Source: A water harvesting manual for urban areasSand FilterFig. No. 5

Dewas FilterFig No. 6

c) Filter for large roof top: This system wasdesigned by R. Jaykumar. When the rainwater isharvested in a large rooftop area, the filtering shouldbe accumulating the excess flow. A system isdesigned with three concentric circular chambersin which the outer chamber is filled with sand, themiddle one with course sand and inner most layerwith pebbles. In this way the area of filtration isincreased for sand, in relation to the courseaggregate and pebbles.

In this system the rainwater reaches to thecenter core and is collected in the sump where it istreated with few tablets of chlorine for consumption.Jayakumar (A builder by profession) (Refer fig.No. 7)

Source – Jayakumar Rain Water Harvest Manual P- 21Jayakumar Filter

Fig. No. 7

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three layers of sponge and 150 mm of thick layer ofcourse sand. Presence of sponge makes the cleaningprocess very easy. Remove the first layer of spongeand soak/ clean it in bucket of water. The sand needsno cleaning at all.

e) Horizontal Roughing filter : The introductionof horizontal filter and slow sand filter to treatsurface water has made safe drinking water availablein coastal pocket of Orrisa. The major componentsare as follows. Filter channel: 1.0m2 in cross section and 8m.inlength laid across the tank embankment, the filterchannel consist of three uniform compartments, firstpocket with broken bricks, second with course sandfollowed by fine sand in third compartment. Thehorizontal roughing filter usually consist of filtermaterial like gravel and course sand thatsuccessively decreases in size from 25 mm to4mm.(Refer Fig. No 8). The bulk of solids in theincoming water is separated by this course sand. Atevery outlet and inlet of channel, fine graded meshis implanted to prevent the entry of finer materialsinto the sump. The length of channel variesaccordingly to the nature of the site selected forsump. The HRF acts as a physical filter and isapplied to retain the solid matter. Slow sand filter isa primary biological filter, used to kill microbes inthe water. Both filter types area generally stable,making full use of the natural purification processof harvested surface water and do not requirechemicals.

Various recharge structures are possible. Someof which promote the percolation of water throughsoil strata at shallow depth (recharge trenches,permeable pavement) where other conduct waterto greater depths from where it joins thegroundwater e.g. recharge well. At many locations,existing structures like wells, pits and tanks can bemodified as recharged structures, eliminating theneed to construct any structure a fresh.

Methods and Techniques :Rooftop rain water Through :a) Recharge Pit : The recharge pit is generally1.5to 3.0 m wide and 2.0m to 3.0 m deep.

The excavated pit is lined with a brick/stonewalls with weep holes at regular intervals. The top area of the pit can be covered withperforated cover. (Refer Fig. No 9)

Horizontal Roughing filterFig No. 8

C) RECHARGED STRUCTURES : Rainwatermay be charged into ground water aquifer throughany structure like dug well, bore well, rechargetrenches and recharge pit.

Source- Centre of Science for VillagesRecharge pit

Fig. No. 9

b) Percolation Pit : Percolation pit is a easiest andmost effective means of harvesting rainwater aregenerally not more than 60cm x 60cm x 60 cm pitsfilled with pebbles or bricks jelly and river sandcovered with perforated concrete slab whenevernecessary. (Refer Fig. No 10)

Filter materialin a soakaway

163

A percolation / absorption pit is a hand boremade in the soil with the help of an augur and filledup with pebbles and river sand on top. The depth ofthese pits will be anywhere between 4 and 8 metersdepending on the nature of the soil. If the soil isclayey, the pit has to be dug to a depth till areasonably sandy stratum is reached. The diameterof these pits will be 25 cm (10 inches). A square /circular collection chamber with silt arrester isprovided at the top. Constructed in the open spaceat required intervals.Size “ 1m x 1m x 1.5m (depth)Filled with broken bricks / pebblesSuitable for sandy sub - soil areaOne unit for 30 m2 area (approx.) (Refer Fig.No.11)

c) PERCOLATION PIT WITH BOREMETHODA borehole to be drilled at the bottom of thepercolation pit. Bore hole size should150 - 300 mmdia. with 10 -15 ft depth (approx.)filled with brokenbricks and suitable for clay area.

In areas where the soil is likely to be clayeyupto say 15ft. and more, it is advisable to go in fora percolation well upto 10ft. or 15ft. and a handbore pit within this well upto a depth of 10ft. to15ft. from its bottom. A PVC pipe of 6in. diameteris inserted into the bore for the entire length. (ReferFig. No 12)

Note :1. Above structures are meant for area with smallcatchment like individual houses.2. RCC slab cover is optional.3. Top (1') portion may be filled with sand.

d) Recharged Trenches : A recharge trench is acontinuous trench excavated in the ground andrefilled with porous material like boulder, pebblesor bricks. A recharge trench can be 0.5 m to 1.0 mwide and 1.0m to 1.5 m deep and length should inthe range of 13-16 meter, which helps for goodpercolation. The length of recharge trench is decidedas per the amount of runoff expected. The rechargetrench should be periodically cleaned ofaccumulated derbies to maintain the intake capacityin term of recharge rate; recharge trenches arerelatively less effective since soil strata at a depthof about 1.5 m is less permeable. For rechargingthrough the recharging trenches fewer precautionshave to be taken to maintain the quality of runoff.Runoff from both paved and unpaved can be tapped.

e) Recharging of service tube well: In this casethe rooftop runoff is not directly fed into the service

Source- Centre of Science for VillageSoak pit (Fig No10)

Source – TWAD BoardPercolation Pit

Fig No. 11

Source – TWAD BoardPercolation pit with bore hole

Fig. No. 12

164

tube well, to avoid the chances of contamination ofgroundwater. Instead, rainwater is collected in arecharged well, which is a temporary storage tank(located near the service tub well) with a borehole,which is shallower than water table depth. Thisborehole has to be provided with a casing pipe toprevent the caving in of soil, if strata are loose. Afilter chamber comparing of sand, gravel andboulder is provided to arrest impurities.

f) Recharge of dug well and abandoned dugwell: in alluvial and hard rock areas, there arethousands of wells which have either gone dry orwhose water level has declined considerably. Thesecan be recharged directly from roof top runoff.Rainwater that is collected on the roof top of thebuilding is diverted by drainpipe to a settlement orfiltration tank from which it flows into the rechargewell (bore well or dug well) if the tube well is usedas for recharging, then the causing outer pipe) shouldbe preferably slotted or performed pipe so that morearea is available for the to percolate. Developing abore well would increases its recharge capacity(developing is the process where water or air isforced into well under pressure to loosen the soilstrata surrounding the bore to make it morepermeable)

1) If dug well used as a recharge then the welllining should have opening (weep holes) at regularinterval to allow seepage of water through the sides.Dug well should be covered to prevent mosquitoesbreeding and entry of leaves and derbies. The bottomof recharged well should be desilted annually tomaintain the intake capacity.Providing the following elements in the system canensure the quality of water entering the rechargewells.1) Filter mesh at entrance point of roofcatchments2) Settlement chamber3) Filter bed.

g) Recharged Trough: To collect the runoff fromthe paved and unpaved areas draining out of acompound, recharged troughs are commonly placedat the entrance of residential / industrial complex.These structures are similar to the recharged trenchexcept for the fact that the excavated portion is not

h) Modified Injection Well: In this method wateris not pumped into the aquifer but allowed topercolate through filter bed, which comprises sandand gravel. The modified injection well is generallya borehole 500 mm diameter, which is drilled to thedesired depth depending upon the geologicalcondition, permeably 2-3.0 m below water table.Inside this hole a slotted pipe of 200 mm diameteris inserted. The annular space between the boreholeand pipe is filled with gravel and developed with acompressor till it gives clear water. To stop thesuspended solid from entering the recharge tubewell, a filter mechanism is provided at top. (ReferFig. No 14)

filled with layer materials. In order to facilate speedyrecharged, boreholes are drilled at regular intervalsin a trench. In design part there is no need ofincorporating the influence of filler materials. (ReferFig. No 13)

Source: A water harvesting manual for urban areasRecharged Trough

Fig. No 13

Modified injection wellFig. No 14

165

In this fig. the roof is covered with plasticwhich is used to collect maximum amount ofrainwater from roof

j) RWH through Continuous ContourTrenching: construction of trench on slope contourto detain water and sediments transported by watergravity down slope generally constructed by lightequipments. These are also called as contour trenchor contour furrows, lined with geotextile and filledwith rock or placed in the form of erosion resistingstructures. (Refer Fig. No 16)

.

l) RWH Through Check Dam: In this smallbarrier built across the direction of water flow onshallow river or stream for the rain water harvestingpurpose. The small dam retains excess water flowduring monsoon rains in small catchment areabehind structure which helps in various ways.Example : In Mahudi village, Dist.Dahod inGujarat. Population of this village was 600. In 1992,the villagers constructed the first check dam on theseasonal river Machhan, with the help ofN.M.Sadguru water and Development Foundation( NMSWDF), a Dahod based NGO. In 2002 thevillagers have constructed a pipeline system to bringdrinking water on tap from the wells near checkdam. Villagers also control the use of water throughthe local village institutions called lift irrigationcommittee. Due to the construction of check dam,the agriculture yield also increased, today formersirrigated about 100 acres of land during the droughtseason. Refer Fig 18.

i) For Rural Area : (Rooftop Rain waterharvesting) In rural areas most of the houses arehaving Mangalore tiles roof. In this gutters areprovided along the periphery of the roof and getcollected in a small tank as shown in fig. No 15.

Rooftop Rain water harvesting (on Mangalore

Rooftop Rain water harvesting Fig. No 15

RWH through Continuous Contour TrenchingFig No 16

k) RWH through Percolation Tank: Thismethod percolation tanks are constructed to storethe rain water which helps in various purpose suchas improvement in ground water table, increasingcrop production, increasing the prosperity of thecountry etc. (Refer Fig. No 17)

Percolation TankFig No 17

Check Dam at Mahudi village, Dist.Dahod in Gujrat

166

m) Open well Recharging by Soak Pit Method(Centre Of Science For Villages) :In this, it ismentioned that construct the slope for surroundedground of well in such a way that total runoff shouldreached toward the well. Construct pits of size 5feetwide and 6.0 feet deep to the both sides of well byleaving 5.0 feet on both sides of well as shown infigure. The length of the pit should be slightly lessthan the half the perimeter of the well. The slope ofthe bottom of pit should be provided in oppositedirection of well. By leaving the space of 6 inchesabove the bottom of pit, provide PVC pipe of 4inches diameter from which water directly flow into the well through the pits. Fill the pits with stonesof size 12inch to 18 inches. While filling care istaken that the gap should remain in between thestones so that rainwater should pass through it. Thebigger size of stones should be placed at bottom ofpit and reduces the size gradually towards the topof pits. Place the course-graded sand above the toplayer of stone. After completing, cover the pit withpolyethylene (plastic) and cover the soil, which isexcavated from the pit. During this, provide spacein to polyethylene for entering the runoff water intothe infiltration pits. Runoff water after passingthrough the filtration pits reaches to the well, whichincreases the level of water in the well. Refer Fig.No 19.

DESIGN CONSIDERATION:The most important components which needs

to be evaluated for designing rain water structuresare

1) Hydrogeology of the area including nature andextent of aquifer, soil cover, topography, depth ofwater table and chemical quality of ground water.2) Area contributing for runoff i.e. how much areaand land use pattern, whether residential or gardenbelt and general built up pattern area.3) Hydro metrological characteristics viz rainfallduration, intensity of rainfall and general pattern.

Quantity of water harvested:The amount of water harvested depend up on

1) The frequency and intensity of rainfall 2)Catchments characteristics3) Water demandWater Harvesting Potential = (Catchments area inSq. m) X (collection efficiency) X (rainfall in mm)

The collection efficiency accounts for the factsthat all the rainwater falling over the area can notbe effectively harvested, because of evaporation,spillage etc. general values are tabulated below (Refer Table No 2 & 3) which are generally used forassessing the potential.

Table No 2

No. Type of catchments Collection efficiency

1 Roof Top 0.75-0.952 Paved area 0.5-0.853 Bare land 0.1-0.24 Green area 0.05-0.1Runoff coefficients for various catchment surfaces

Check DamFig No. 18 Source _Centre Of Science For Village

Open well Recharging by Soak Pit Method sFig No. 19

167

cooking and drinking purpose is 10 liter/ cap/ dayFor family of six person = 60 liters.For 245 days = 245 X 60 = 14700 liters.

As per the factor of safety the tank should bebuilt 20 % larger than the requirement i.e. 17640liters. This tank meets the basic water requirementfor a family of six members for dry period. By fixingthe height of the tank, the diameter can be calculated.

Legislation of RWH.Kerala: The Kerala Municipality Building Rules,1999 was amended by a notification dated January12, 2004 issued by the Government of Kerala toinclude rainwater harvesting structures in newconstruction.

109. A Rooftop rainwater harvestingagreements.1) Unless otherwise stipulatedspecifically in a town planning scheme, workableroof top rainwater harvesting arrangements shall beprovided as in integral part of all new buildingconstructs for the following occupancies, namelyi) Group A1 — Residential (with floor area of100 m2 or more and plot area 200 m2 or more)ii) Group A2 — Special Residential.iii) Group B — Educational.iv) Group C — Medical / Hospital.v) Group D – Assemblyvi) Group E – Office / Business.vii) Group G1 and Group G2 industrial (Only forworkshop, assembly plant, laboratories, dry-cleaning plant, diaries food processing unit and anyother occupancies noticed by the government fromtime to time).Provided that the floor area to beconstructed shall be the total floor area in all floors:provided further that, the rainwater harvestingarrangement is not mandatory for thatched roofedbuilding.2) The components of workable rooftop rainwater harvesting arrangements as stipulated in sub-rule (1) above, shall includei) Roof catchments areaii) Roof guttersiii) Down pipe and first flush pipe arrangementiv) Filter unitv) Storage tank with provision of drawing waterand spillover3) The minimum capacity of storage tank asstipulated in sub- rule (2) (v) of the roof top

Table No 3

Type of Catchment CoefficientsRoof Catchments -Tiles 0.8-0.9 - Corrugated metal sheets 0.7- 0.9Ground surface coverings -Concrete 0.6-0.8 - Brick pavement 0.5- 0.6Untreated ground catchments - Soil on slopes less than 10 per cent 0.0-0.3 - Rocky natural catchments 0.2 - 0.5Untreated ground catchments - Soil on slopes less than 10 per cent 1.0-0.3 - Rocky natural catchments 0.2 - 0.5

Source : Pacey, Arnold and Cullis, Adrian 1989, RainwaterHarvesting: The collection of rainfall and runoff in ruralareas, Intermediate Technology Publications, London.

Example :Area of terrace = 150 sq.m.Height of Rainfall = 500 mm (0.5m)Volume of rainfall = 150 x 0.5 = 7.5 m3 = 75000 Lit. Assuming that 70 – 80 % of the total rainfall iseffectively harvestedVolume of water harvested = 75000 X 0.7 = 52500 liters.Generally water required for drinking, cooking is10 liter / capita/daySuppose the family of six people Total quantity of water required / family = 10 x 6

= 60 liters.For a year = 365 x 60

= 21900 liters.The water required for family for drinking and

cooking purpose is less than the rain water harvestedi.e. harvested water is double than the water requiredfor main purpose.

Design of Storage tankTank capacity : Tank capacity is based on dryperiod i.e. the period between the two consecutiverainy seasons. Suppose monsoon is for four monthsi.e. 120 days , then the dry days are 245.

We know that quantity of water required for

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harvesting arrangement shall be at the rate givenbelow

Group A1 25 liters/ m2

Group A2 25 liters/ m2

Group B 50 liters/ m2

Group C 50 liters/ m2

Group D 50 liters/ m2

Group E 50 liters/ m2

Group F NilGroup G1 and G2 50 liters/ m2

Group H 25 liters/ m2

Group I Nil

New Delhi :Since June 2001, the Ministry of Urbanaffairs and Poverty Alleviation has made rainwater-harvesting mandatory in all new buildings with aroof area of more than 100 sq m and in all plotswith an area of more than 1000 sq m, that are beingdeveloped. The Central Ground Water Authority(CGWA) has made rainwater harvesting mandatoryin all institutions and residential colonies in notifiedareas (South and southwest Delhi and adjoiningareas like Faridabad, Gurgaon and Ghaziabad). Thisis also applicable to all the buildings in notified areasthat have tubewells. The deadline for this was forMarch 31, 2002.

Indore (Madhya Pradesh): Rainwater harvestinghas been made mandatory in all new buildings withan area of 250 sq m or more. A rebate of 6 per centon property tax has been offered as an incentive forimplementing rainwater-harvesting systems.

Kanpur (Uttar Pradesh): Rainwater harvesting hasbeen made mandatory in all new buildings with anarea of 1000 sq m or more.

Hyderabad (Andhra Pradesh): Rainwaterharvesting has been made mandatory in all newbuildings with an area of 300 sq m or more. Tentativefor enforcing this deadline was June 2001.

Tamil Nadu: Through an ordinance titled ThailandMuncipal Laws ordinance, 2003, dated July 19,2003, the government of Tamil Nadu has maderainwater harvesting mandatory for all the buildings,both public and private, in the state. The deadline

to construct rainwater harvesting structures isAugust 31, 2003. The ordinance cautions, “Wherethe rain water harvesting structure is not providedas required, the Commissioner or any personauthorized by him in this behalf may, after givingnotice to the owner or occupier of the building, causerain water harvesting structure to be provided in suchbuilding and recover the cost of such provision alongwith the incidental expense thereof in the samemanner as property tax”. It also warns the citizenson disconnection of water supply connectionprovided rainwater-harvesting structures are notprovided.

Haryana: Haryana Urban Development Authority(HUDA) has made rainwater-harvesting mandatoryin all new buildings irrespective of roof area. In thenotified areas in Gurgaon town and the adjoiningindustrial areas all the institutions and residentialcolonies have been asked to adopt water harvestingby the CGWA. This is also applicable to all thebuildings in notified areas having a tubewell,deadline was for March 31, 2002. The CGWA hasalso banned drilling of tubewells in notified areas.

Rajasthan: The state government has maderainwater harvesting mandatory for all public andestablishments and all properties in plot coveringmore than 500 sq m in urban areas.Mumbai:The state government has made rainwater-harvesting mandatory for all buildings that are beingconstructed on plots that are more than 1,000 sq min size. The deadline set for this was October 2002.

Gujarat: The state roads and buildings departmenthas made rainwater harvesting mandatory for allgovernment buildings.

Status of RWH in Nagpur District for the yearof 2005-2006

(Mahatma Jotiba Fule Jal Bhomi SandharanAbhiyan)(Refer Table No. 4)

References :1) Centre for Science and Environment ( CSE)2) National building code.3) A water-harvesting manual for urban area.4) S. Vishwanath. Domestic Rainwater harvesting.Some application in Banglore, India5) Centre of science for villages ( www.csvtech.org)

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Table No 4

No. Well Well Roof top rain Roof top rainrecharging recharging water harvesting water harvesting(Target) (Achieved) (Target) (Achieved)

1 Nagpur 150 32 150 1172 Kamthi 125 58 125 1283 Hingna 150 39 150 2004 Kalmeshwar 150 1505 Katol 150 176 150 3106 Narkhed 150 1507 Sawaner 150 70 150 588 Parshivni 125 1259 Ramtek 150 48 150 5910 Mouda 125 20 125 2711 Kuhi 125 0 125 0612 Umared 125 14 125 4413 Bhivapur 125 125

TOTAL 1800 457 1800 949

No. Well recharging Roof top rain Roof top rain(Target) water harvesting water harvesting

(Target) (Target)Government buildings

1 Nagpur 150 150 1002 Kamthi 125 125 1003 Hingna 150 150 1504 Kalmeshwar 150 150 1005 Katol 150 150 1506 Narkhed 150 150 1007 Sawaner 150 150 1008 Parshivni 125 125 1009 Ramtek 150 150 15010 Mouda 125 125 10011 Kuhi 125 125 10012 Umared 125 125 10013 Bhivapur 125 125 150

TOTAL 1800 1800 1500

Target of RWH in Nagpur District for the year of 2006-2007( Mahatma Jotiba Fule Jal Bhomi Sandharan Abhiyan)

(Refer Table No5)

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India; Rain Water Harvesting, Conservation and Management Strategies for Urban and Rural Sectors

Design

india water

early water

water management

ground water

rain water harvesting

becomingdescribed water

water problemsrain

roof water