Rain water harvesting

RAIN WATER HARVESTING

Presentation by: Achint Jindal (IT- Branch)

Project Guide: Dr. Tanuja Nautiyal

Contents Introduction

Concept and Technology of Rainwater Harvesting

Average Rainfall of States in India

Availability of Rainwater Through Roof Top Rainwater Harvesting

Runoff Coefficients for Various Catchments Surfaces

Rainwater Harvesting System

Treatment Techniques

Rainwater Harvesting System at Siel Chemical Complex

Every year, the water level in the state PUNJAB goes down by one meter. If this continues, the state will soon turn into a desert. So it is necessary to save every drop of water.

“Every commercial building as well as big houses in the state must install Rain water harvesting system to save water”

Introduction

What is rain water harvesting ?

It is the activity of direct collection of rain water

Rain water can be stored for direct use or can be recharged into the ground water aquifer

Rain Water in IndiaTotal annual rainfall in India: 400 million hectare-

meters (area x height)India’s area: 329 million hectaresIf evenly spread, average height: 1.28mActual distribution:

Highly skewed area-wiseThe desert receives less than 200mm annually,

while Cherrapunji receives 11,400mmBut almost every part of India receives at least

100mm annuallyKey: even 100mm annual rainfall sufficient if

harvested properly and where it falls

But….Temporal distribution of rain in India also skewedRainfall in India seasonal (unlike Western countries)Most of the country receives rainfall only for about

100 hours each yearRough rule of thumb: #cm of rain = #hours rain

receivedE.g.: Jodhpur receives 40cm of rain in about 40

hoursNatural implication of such skew:

Most of the rain water lost due to runoffsUnlike the west, very little water percolates into

the groundHence, the importance of harvesting structures

for local self-sufficiency

Sl.No. State Meteorological Divisions

Average annual 

rainfall (mm)

1Andaman and

Nicobar Andaman and Nicobar Islands 2,967

2Arunachal

Pradesh Arunachal Pradesh 2,782

3 Assam Assam and Meghalaya 2,818

4 Meghalaya Assam and Meghalaya 2,818

5 NagalandNagaland, Manipur, Mizoram an

Tripura 1,881

6 ManipurNagaland, Manipur, Mizoram

andTripura 1,881

7 MizoramNagaland, Manipur, Mizoram

andTripura 1,881

8 TripuraNagaland, Manipur, Mizoram

andTripura 1,881

9 West Bengal

Sub-Himalayan West Bengal and Sikkim 2,739

Gangetic West Bengal 1,439

10 SikkimSub-Himalayan West Bengal and

Sikkim 2,739

Average Rainfall of States in India

Sl. No. State Meteorological Divisions

Average annual 

rainfall (mm)

11 Orissa Orissa 1,489

12 Bihar

Bihar Plateau 1,326

Bihar Plains 1,186

13 Uttar Pradesh

Uttar Pradesh 1,025

Plain of West Uttar Pradesh 896

 Hills of West Uttar Pradesh 1,667

14 Haryana Haryana, Chandigarh and Delhi 617

15 Delhi Haryana, Chandigarh and Delhi 617

16 Chandigarh Haryana, Chandigarh and Delhi 617

17 Punjab Punjab 649

18Himachal Pradesh Himachal Pradesh 1,251

19Jammu and Kashmir Jammu and Kashmir 1,011

20 Rajasthan

West Rajasthan 313

East Rajasthan 675

Sl. No. State Meteorological Divisions

Average annual 

rainfall (mm)

21 Madhya Pradesh

Madhya Pradesh 1,017

East Madhya Pradesh 1,338

22 Gujarat

Gujarat region 1,107

Saurashtra and Kachchh 578

23 Goa Konkan and Goa 3,005

24 Maharashtra

Konkan and Goa 3,005

Madhya Maharashtra 901

Marathwada 882

 Vidarbha 1,034

25 Andhra Pradesh

Coastal Andhra Pradesh 1,094

Telengana 961

Rayalaseema 680

26 Tamil NaduTamil Nadu and Pondicherry 998

27 PondicherryTamil Nadu and Pondicherry 998

28 Karnataka

Coastal Karnataka 3,456

North Interior Karnataka 731

South Interior Karnataka 1,126

29 Kerala Kerala 3,055

30 Lakshadweep Lakshadweep 1,515

Why Rain water harvesting To conserve & augment the storage

of ground waterTo reduce water table depletionTo improve the quality of ground

water To arrest sea water intrusion in

coastal areas To avoid flood & water stagnation

in urban areas

4

Concept and Technology of Rainwater Harvesting Rainwater is a free source of nearly pure water and rainwater

harvesting refers to collection and storage of rainwater and other activities aimed at harvesting surface and ground water. It also includes prevention of losses through evaporation and seepage and all other hydrological and engineering interventions, aimed at conservation and efficient utilization of the limited water. In general, water harvestings the activity of direct collection of rainwater. The rainwater collected can be stored for direct use or can be recharged into the ground water.

There are two main techniques of rain water harvestings.

Storage of rainwater on surface for future use.

Recharge to ground water.

RAIN WATER HARVESTINGRain

Roof Top

Filtration

or

Recharge to ground water

Storage

Rooftop Water

Technology of Rainwater Harvesting

Example of Small level Rain Water harvesting in villages in India

Water available from Roof = Annual rainfall (in mm) x roof area (in sq. m) x co-efficient of run off for roof

Suppose the system has to be designed for meeting drinking water requirement of a 5-member family living in a building with a rooftop area of 100 sq.m. Average annual rainfall in the region is 600 mm. Daily drinking water requirement per person (drinking and cooking) is 10 liters.

We shall first calculate the maximum amount of rainfall that can be harvested from the rooftop .Following details are available:Area of the catchments (A) = 100 sq.m.Average annual rainfall (R) = 600 mm (0.6 m)Runoff coefficient (C) = 0.85Annual water harvesting potential from 100 sq.m. roof= A x R x C= 100 x 0.6 x 0.85= 51 cu.m. (51,000 ltr)

Availability of Rainwater Through Roof Top Rainwater Harvesting

The tank capacity has to be designed for the dry period, i.e., the period between the two consecutive rainy seasons.

With the rainy season extending over four months, the dry season is of 245 days. Particular care must be taken to ensure thatpotable water is not contaminated by the collected rainwater.

Drinking water requirement for the family(dry season) = 245 x 5 x 10

= 12,250 ltr.

As a safety factor, the tank should be built 20 per cent larger than required, i.e., 14,700 ltr. This tank can meet the basic drinking water requirement of a 5-member family for the dry period.

All rainwater-harvesting systems comprise six basic components irrespective of the size of the system.

1. Catchments area/roof: The surface upon which the rain falls; the roof has to be appropriately sloped preferably towards the direction of storage and recharge.

2. Gutters and downspouts: The transport channels from catchments surface to storage; these have to be designed depending on site, rainfall characteristics and roof characteristics.

3. Leaf screens and roof washers: The systems that remove contaminants and debris; a first rain separator has to be put in place to divert and manage the first 2.5 mm of rain.

4. Storage tanks: Sumps, tanks etc. where collected rain-water is safely stored or recharging the ground water through open wells, bore wells or percolation pits etc.

5. Conveying: The delivery system for the treated rainwater, either by gravity or pump;

6. Water treatment: Filters to remove solids and organic material and equipment, and additives to settle, filter, and disinfect.

Rain Water Distribution & Management

Screening Methods Location Results

Strainers and Leaf Screens

Gutters and Leaders

Prevent leaves and otherdebris from

Settling

Sedimentation

Within Tank Settles particulate matter

Treatment Techniques

Filtering

In-line/Multi-CartridgeActivated CarbonReverse OsmosisMixed MediaSlow Sand

After PumpAt TapAt Tap Separate Tank Separate Tank

Sieves sedimentRemoves chlorineRemoves contaminantsTraps particulate matterTraps particulate matter

Disinfecting

Boiling/DistillingChemical TreatmentsUltraviolet Light

Ozonation

Before useWithin tankAfter the activated carbon filter Before Tap

Kills microorganismsKills microorganismsKills microorganismsKills microorganisms

Rainwater Harvesting System at Siel Chemical Complex

Rainwater Harvesting System at Siel Chemical Complex SIEL Chemical Complex is a Caustic Soda production plant located at Rajpura. It has ISO 14000 certification and the organization is very much concerned to improve the Environmental standards within and outside the premises of company. To improve the Ground water level in the surrounding areas, organization is trying to implement the Rain Water Harvesting within the premises.

In SCC, we are having 02 nos units of rain water harvesting . The first unit of rain water harvesting was installed and taken in operation w.e.f. July 20,2007.

It is estimated that around 500m3 of water will be charged into the ground in a year, with an average rainfall of 82 cms .

Rainwater Harvesting System at Siel Chemical Complex

Here we are considering the only Rooftop of A & PO building, Security block building and HR and Administrative block building for rainwater harvesting.Rooftop area of A&PO building = 304 sq. m.Rooftop area of security block building = 192 sq. m.Rooftop area of HR and administrative block building = 662 sq. m.Total Rooftop Area = 1158sq.m.Average Rainfall in this region = 82.23 cm. = .82 m.Assuming that 60% of total rainfall is effectively harvested.Volume of water harvested = 1158 X .82 X .6 cu. m. = 569.736 cu. m. = 569736 ltr.So we can save 569 m3. of water annually from above said building

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