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In
the Rajender nagar area the first Layer of clay and kankar extends
to depth of 4m bgl. This is followed by quartzite formation. The fractured
and jointed layers of the formation acts as water bearing formation.
A
comparative study of water level map of 1960 and 2002 shows in Rajender
nagar the water level which was at 10 to 15m below ground level has
gone down to 20 to 30 mts below ground water level.
In
Rajender nagar fresh water occurs at all depth.
IV.CASE STUDIES
JANKI DEVI COLLEGE |
RAINWATER AVAILABLE FOR HARVESTING
Total rooftop and surface area:
32,170 square metres (sq m)
Average annual rainfall in Delhi:
611 millimetres (mm)
Total volume of rainwater harvested: 6880 cubic metres (m³) or
68,80,000 litres This represents about 35 per cent of the total rainwater
harvesting potential.
WATER SUPPLY SOURCE
The three borewells inside the campus cater to the total water requirements
of the college.
RAINWATER HARVESTING SYSTEM
ROOFTOP WATER HARVESTING: The runoff from the terrace of the college
building is channelised into three recharge wells located at three
different locations, each measuring 1m x 1m x 2m. All the rooftop
rainwater outlets, except that from the Tutorial Block, discharge
into stormwater drains and then to the recharge structures. In the
Tutorial Block, a network of pipes linked through chambers take the
rainwater to the recharge wells. To facilitate groundwater recharge,
all structures are provided with 15m deep borewells of 150mm diameter.
Layer of bricks filled inside the recharge well ensures proper filtration
of harvested water.
SURFACE RUNOFF WATER HARVESTING: The runoff from the unpaved area
is intercepted at the main gate by a collection trench. From here
the runoff eventually drains into an abandoned open well, which facilitates
groundwater recharge. The project was implemented in June 2001. The
cost of the entire rainwater harvesting system was Rs 0.70 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 20 mts bgl depth.
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