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In the Vasant Kunj area the first Layer of clay and kankar
extends to depth of 12m bgl. This is followed by layer of kankar and
silt from 12 to 25m below ground level. This is again underlain by
layer of clay and kankar which extends even beyond 40m bgl.
A comparative
study of water level map of 1960 and 2002 shows in Vasant Kunj the
water level which was at 5 to 10m below ground level has gone down
to 20 to 30 mts below ground water level.
In
Vasant kunj fresh water occurs at all depths.
IV.CASE STUDIES
INDIAN SPINAL INJURY CENTRE |
RAINWATER AVAILABLE FOR HARVESTING
Total area - 52,598 square metres (Sq m)
Average annual rainfall in Delhi - 611 millimetre (mm)
Total volume of water harvested - 27,317 cubic metre (m³) or
273,17,000 litres
This represents 85 per cent of the total rainwater harvesting potential.
WATER SUPPLY SOURCE
The Centre's water requirements are met by four borewells located
on the hospital premises.
RAINWATER HARVESTING SYSTEM
Hospital building: The rooftop rainwater and the surface runoff from
the western part of the building are drained into a stormwater drain
that runs to the west side of the building. This water is diverted
into a recharge well located at the northwest corner of the campus
near an existing borewell. A part of the rooftop rainwater from the
east side of the hospital building and runoff from the paved area
are diverted through a network of pipes and collection chambers to
another stormwater drain that runs to the north of the premises. This
runoff is also diverted to the same recharge well located near the
borewell. This recharge well is 2.75m in length and 2.13m in breadth
and is 1.82m deep. This recharge well is provided with a recharge
bore of 100mm diameter and is 20m deep. This recharge well has two
compartments, and the runoff water undergoes two stages of filtering
before it enters the recharge borewell. Layers of brickbats and sand
ensure the quality of water used for recharging purposes.Staff quarters
area: The rooftop rainwater and the surface runoff from the paved
and unpaved areas are collected in chambers interlinked by pipes.
This water is used for recharge purposes by diverting it to two recharge
wells. Part of this water is diverted to recharge the east side of
the staff quarters and the rest is harvested by converting a dry borewell
into recharge well near the entrance of staff quarters. These recharge
wells are measure 1.5m in diameter and are 2m deep; the recharge borewell
measures 20 meters. The implementation was completed on October 2002
and the water level on February 2003 was measured at 32m below ground
level (bgl).The cost of the entire rainwater harvesting system was
Rs 0.80 lakh.
| V.RECOMMENDATION FOR AUGMENTATION
OF GROUNDWATER |
In this area the rainwater can be diverted to a depth of
15 to 20mts. By doing this the rainwater will under go a natural filtration
in the subsoil before it reaches the main aquifer. The recharge bore
in the recharge well should be of 15 to 20mts bgl.
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