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In
the Dwarka clay and kankar formation exists in the top layer upto
a depth of 4m below ground level. This layer of clay is followed by
Kankar and silt upto a depth of 68m below ground level.
A
comparative study of water level map of 1960 and 2002 shows in Dwarka
the water level which was at 2 to 5m below ground level has gone down
to 5 to 10 mts below ground water level.
In
Dwarka the occurrence of fresh water in alluvium formation is upto
a depth of 18mts. Below that level saline or brackish water occurs.
The amount of fresh water is decreasing due to extraction.
CIVIL SUPPLIES, CGHS, PLOT NO. 6, DWARKA This is Cooperative
Group Housing with a total plot area of 6500 sqm. The Catchment area
details are as follows:
Rooftop: 2145 sqm
Paved: 3775 sqm
Unpaved: 580 sqm
RAINWATER AVAILABLE FOR HARVESTING Total rooftop and surface area:
6500 sqm.
Average annual rainfall in Delhi: 611mm
Total volume of rainwater harvested:
Paved area (5920x.611x.85 = 3074 cubic metres)
Unpaved area (580x.611x.30 = 106 cubic metres)
Rain water-harvesting potential: 3,180,000 litres.
WATER SUPPLY SOURCE The housing gets water supply through MCD and
from a tubewell (90 ft deep)
RAINWATER HARVESTING SYSTEM Rooftop rainwater harvesting: The rooftop
rainwater from the four blocks is diverted into the recharge well
through network of pipes opening into the storm water drains.
Surface runoff harvesting: A peripheral storm water drain is running
all around the periphery and is connected to the recharge well. Two
Recharge wells were observed. They were approximately 4.5m x 1.75mx
2m in size with a bore well 50 ft deep.
This project was designed by CGWB. The total cost of the project was
about Rs 77,500 and the project was implemented in July 2002.
AIR FORCE AND NAVAL OFFICERS CGHS, PLOT NO. 11, SECTOR
7, DWARKA This housing society has a total plot area of 27,512
sqm. The Catchment area details are as follows:
Rooftop: 9078 sqm
Paved: 15672 sqm
Unpaved: 2762
RAINWATER AVAILABLE FOR HARVESTING Total volume of rainwater available
for harvesting:
Rooftop: 9078x.611x.85 = 4714 cubic metres
Paved: 15672x.611x.7 = 6702 cubic metres
Unpaved: 2762x.611x.7 = 506 cubic metres
Rainwater harvesting potential: 11,922,000 litres
WATER SUPPLY SOURCE The housing society gets its water supply through
MCD and a tube well 250 ft deep.
RAINWATER HARVESTING SYSTEM There are four Recharge wells constructed
in the colony. Two of them are 5m x 1.7m and 50 ft deep. The third
one is 4m x 1.7m in size and 50 ft deep and fourth well is 2.4m x
2.4m in size and 50 ft deep. All the water from the rooftops collects
in the storm water drains which then meet the recharge well.
Surface runoff harvesting: the water from all the paved areas is collected
into the storm water drains, which is then collected to a recharge
well. Apart from this, three drains are provided in the colony in
between the blocks, which collect the water from the paved areas and
drain into the storm water drains.The total cost of the project is
2.05 lakhs and it was implemented on May, 2003-07-09
| V.RECOMMENDATION FOR AUGMENTATION
OF GROUNDWATER |
The
intake capacity of recharge structures will be low in shallow water
table condition. Hence in Dwarka where the ground water level is below
10m rainwater harvesting can be taken up. The project was designed
by CGWB.
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