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In the Lodi road area the first Layer of clay and kankar
extends to depth of 8m bgl. This is followed by kankar and silt upto
20m, this layer is again underlain by clay and kankar upto 50m bgl.
A comparative
study of water level map of 1960 and 2002 shows in Lodi road the water
level which was at 5 to 10m below ground level has gone down to 10
to 15 mts below ground water level.
In
Lodi road fresh water occurs in shallow zones.
IV.CASE STUDIES
FORD FOUNDATION |
RAINWATER AVAILABLE FOR HARVESTING Total area - 12,500 square metres
(Sq m)
Average annual rainfall in Delhi - 611 millimetre (mm)
Total volume of water harvested - 6491.8 cubic metre (m³) or
64,91,875 litres This is 85 per cent of total rainwater harvesting
potential.
WATER SUPPLY SOURCE
The organisation's water requirement is fulfilled by two tubewells
and is supplemented by Municipal water supply. Approximately 15,000
litres of water is used for potable and non-potable purposes.
RAINWATER HARVESTING SYSTEM
Rooftop rainwater and runoff water from paved and unpaved areas: The
rooftop rainwater from the northern portion of the UNDP building is
diverted to a recharge well located near the existing borewell through
a network of pipes and collection chambers. The recharge well is 2m
in diameter and 3.5 m deep, with a recharge bore which is 100mm in
diameter and 5m deep. The rooftop rainwater runoff from the southern
part of the UNDP building is collected in a chamber and diverted to
a 1m x 1m x 1m recharge well with a recharge bore of 100mm diameter
and 5m deep. A layer of pebbles and sand filled inside the recharge
well acts as filtering media, ensuring the quality of water being
recharged.
Surface water harvesting:
Surface runoff from paved and unpaved sources and part of the rooftop
rainwater are trapped by constructing recharge troughs near Gates
I, III, V and VI. These troughs are 5m long, 0.7m wide and 1.5m deep.
Each trough is provided with recharge bores that are 100mm in diameter
and 5m deep. Implementation of the system was completed on November
2000 and the water level on February 2003 was recorded at 9.80m below
ground level (bgl).The cost of the entire rainwater harvesting system
was Rs 4 lakh.
| V.RECOMMENDATION FOR AUGMENTATION
OF GROUNDWATER |
In this area shallow recharge wells can be constructed.
The non potable water from the subsurface formation can be used for
non potable water.
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