Rainwater Harvesting

Presented by:

Shahid Sohail Director STP (CDA)

• GLOBAL PERSPECTIVE

• PRESENT WATER SITUATION

• RAINWATER POTENTIAL

• RWH PRACTICES

• RECOMMENDATION

Nearly 97% of the world's water is saltwater or otherwise undrinkable. Another 2% is held in ice caps and glaciers. That leaves just one percent for all of humanity's needs i.e. agricultural, residential, manufacturing, and community needs.

(United States Geological Survey)

Each day, the sun evaporates 1,000,000,000,000 (one trillion) tons of water.

(United States Geological Survey)

If present consumption patterns continue, two out of every three persons on Earth will live in water-stressed conditions by the year 2025.

(United Nations Environment Program)

Population Projection

Statistical Division, Government of Pakistan

Projected Water Demand

Asian Development Bank

Water Production – Sourcewise

JUNE 2, 2008

JUNE 2, 2008* 55% leakage in the system (JBIC – SAPS study)

Water Production - Overall

Per Capita Water Availability

• Designed 100 GPCD• Actual Prod. 71 GPCD• After Leakages 32 GPCD

Statistical Division, Government of Pakistan

JUNE 2, 2008

Water Production - Tubewells

POINT TO PONDER

In the recent Past 10 Tubewells have dried

down and others are fast depleting

Production Division – II - CDA

Although CDA is vowed to Fill this Gap

through Mega Projects, Yet there is a dire

need to Protect the Existing Sources.

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

1990 41.1 105.1 160.2 55.3 0.0 29.4 327.4 436.0 168.3 21.1 7.9 177.9 1093.7

1991 9.2 106.8 103.9 116.6 16.8 88.6 251.8 264.2 211.5 3.3 3.8 17.1 1193.6

1992 99.2 91.3 119.1 30.5 36.8 14.5 256.7 305.0 257.9 9.0 34.0 7.9 956.9

1993 36.4 30.0 140.6 22.0 44.7 77.8 152.7 211.2 15.4 6.0 15.4 0.0 752.2

1994 36.1 51.4 36.0 69.3 36.0 54.8 596.7 637.7 56.2 29.8 1.0 93.2 1698.2

1995 31.5 99.8 104.3 107.4 17.2 20.5 743.3 331.8 39.8 64.6 20.0 35.0 1615.2

1996 81.5 121.9 130.1 47.2 32.0 145.2 298.5 329.1 72.0 60.0 3.0 6.0 1326.5

1997 39.0 20.3 84.3 172.2 46.1 64.7 194.8 496.4 158.0 95.8 22.4 19.8 1413.8

1998 36.7 248.8 75.8 110.0 29.6 19.3 306.0 322.4 138.0 11.0 0.0 0.0 1297.6

1999 83.1 28.5 80.8 2.0 16.1 33.0 232.3 334.0 145.0 9.5 35.0 0.0 999.3

2000 129.0 70.6 18.0 2.0 11.0 37.0 207.0 381.0 129.0 0.0 0.0 14.0 998.6

2001 0.0 4.0 40.0 24.2 16.5 153.0 647.0 207.0 44.0 33.0 7.0 2.0 1177.7

2002 7.0 38.0 32.0 6.0 12.0 155.0 109.0 0.0 157.0 38.0 0.0 26.5 580.5

2003 37.7 235.4 105.9 22.3 18.2 90.2 407.1 212.8 292.5 5.3 27.5 49.9 1504.8

2004 146.8 48.0 0.0 78.0 40.0 130.0 128.5 313.0 46.1 76.0 22.0 28.0 1056.4

2005 97.0 213.0 87.0 0.0 33.0 16.0 181.0 211.0 86.0 36.0 6.0 0.0 966.0

2006 70.0 27.0 61.0 19.0 76.0 126.0 504.0 418.0 52.0 92.0 20.0 133.0 1598.0

Mean 57.7 90.6 81.1 52.0 28.4 73.8 326.1 274.7 121.7 34.7 13.2 35.9 1189.9

RAINFALL DATA OF ISLAMABAD

(Pakistan Meteorological Department)

Average yearly rainfall = 1.19 m

Area per sector = 4 x 106 sq.m

Total available rainwater = 4.76 x 106 cu.m / year

= 1047.2 M. gallons / year

= 2.87 MGD

Rainwater utilization = 60%

Available water for use= 1.72 MGD

Sector Population = 40,000

Per capital Availability = 43 GPCD

Sectorwise Availability of Rainwater

Average yearly rainfall = 1.19 m

Area rooftop Area = 250 sq.m

Total available rainwater = 295.5 cu.m / year

= 65,450 gallons / year

Rainwater utilization = 80%

Available water for use= 52360 gallons / year

Person per House = 6

Per capital Availability = 24 GPCD

House wise Availability of Rainwater

Surface (Spreading) Methods

• Flooding

• Basin & Percolation Tanks

• Stream Augmentation

• Ditch & Furrow system

Sub-Surface Methods

• Recharge Well

• Pits & Shafts

• Dug wells

• Soakaways

Roof Top Harvesting

• The rain water in urban area can be conserved through Roof Top Rain Water Harvesting Techniques for grey water usage and artificial recharge to ground water.

The advantages of Rain Water Harvesting are:

• Rainwater is bacteriologically pure, free from organic

matter and soft in nature.

• It will help in reducing the flood hazard.

• Improve the quality of existing ground water through

dilution.

• Rainwater may be harnessed at place of need and may

be utilized at time of need.

• The structures required for harvesting the rainwater are

simple, economical and eco-friendly.

RWH in Islamabad

• Redesign of storm drainage system to allow infiltration of

water into the ground.

• Construction of recharge wells at appropriate places

• Utilizing abandoned tubewells for recharging with minor

modifications.

• Rights of usage of ground water be enforced through

legislation.

RWH in Islamabad

• Use of Indigenous plants be preferred.

• Enforcing rooftop RWH on houses for grey water usage.

• Mandatory for new houses

• Mandatory for existing houses having private wells