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In the Hamdard area the first Layer of clay and kankar
extends to depth of 8m bgl. This is followed by a layer of kankar
and silt upto 20m, this is under lain by weathered and fractured quartzites.
A comparative
study of water level map of 1960 and 2002 shows in Hamdard the water
level which was at 20 to 30m below ground level has gone down to 30
to 45 mts below ground water level.
In
Hamdard the fresh water occurs at all depths.
IV.CASE STUDIES
JAMIA HAMDARD UNIVERSITY |
RAINWATER AVAILABLE FOR HARVESTING
Total rooftop and surface area: 3,15,380 square metres (sq m)
Average annual rainfall in Delhi : 611 millimetres (mm)
Total volume of rainwater harvested: 67444 cubic meters (m³)
or 6,74,44,000 litres.
This represents 35 per cent of total rainwater harvesting potential
WATER SUPPLY SOURCE
The daily water requirement of approximately six lakh litres is extracted
from six borewells. The remaining requirement is met through private
water tankers.
RAINWATER HARVESTING SYSTEM
Rainwater from various catchments, such as rooftop, surface runoff
from open areas and runoff from the Jahanpanah Reserve Forest are
harvested.
1. ROOFTOP RAINWATER HARVESTING
a) Rooftop rainwater harvesting at the library building Rainwater
from the library's rooftop is taken to a desilting chamber measuring
2m x 2m x 3m through a closed drain. A baffle wall divides the desilting
chamber into two compartments -- settlement and filtering chambers.
The rainwater first enters the desilting chamber where the silt gets
collected and then overflows into the filtering chamber. The filtering
chamber has pebbles, which further filters the rainwater before diverting
it into the recharge well. The recharge well measures 1.5m x 1.5m
x 3m in size with a 30m deep recharge borewell measuring 100mm in
diameter.
b) Rooftop rainwater harvesting at the girls' hostel Rainwater from
the hostel terrace is diverted to a circular recharge well 2m in diameter
and 3m deep through a closed channel. A desilting chamber is created
by constructing a baffle wall inside the recharge well. The rainwater
from the terrace flows into the desilting chamber, where the silt
gets deposited. The silt-free water overflows into the recharge well.
The recharge well encompasses a borewell which is 100mm in diameter
and 30m deep.
2. SURFACE RUNOFF HARVESTING
a) Surface runoff harvesting near library building
Surface runoff from the paved and unpaved areas surrounding the library
is collected in two trenches located in the eastern part of the campus
(near Gates 5 and 6). The runoff collected near Gate 5 is diverted
into a recharge well. Similarly, the runoff from the northern side
of the building is drained into an abandoned open dugwell near Gate
6.
b) Surface runoff harvesting from Jahanpanah Reserve Forest
The surface runoff from the Jahanpanah reserve forest collects in
a pond from where it flows through a stormwater drain adjacent to
the Scholars' House. This runoff water is channelised into a desilting
chamber and then into a recharge well which measures 2m x 2m x 3m
with the help of a 1m high diversion wall.
3. SURFACE RUNOFF AND ROOFTOP RAINWATER HARVESTING AT HAMDARD ARCHIVES
& RESEARCH CENTRE
The rooftop rainwater and the surface runoff are collected in an open
drain which runs adjacent to the building. This drain, measuring 450mm
in width and 300mm in depth carries the rainwater into the desilting
chamber. The silt-free water is diverted to a recharge well which
has a borewell to recharge the groundwater. The project was implemented
in June 2001. The total cost for implementation of recharge structures
was Rs. 6.52 lakhs.
| IV.RECOMMENDATION FOR AUGMENTATION
OF GROUNDWATER |
In this area the rainwater can be diverted to a depth of
20 to 25mts. 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 20 to 25mts bgl depth.
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