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In
the Vasant vihar road area the first Layer of clay and kankar extends
to depth of 12m bgl. This is followed by quartzite formation. The
fractured and jointed rock in the quartzite formation acts as a water
bearing formation.
A
comparative study of water level map of 1960 and 2002 shows in Vasant
vihar 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 Vihar fresh water occurs at all depths.
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IV.CASE STUDIES
SRIRAM SCHOOL
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RAINWATER AVAILABLE FOR HARVESTING
Total rooftop and surface area 6000 square metres (sq m)
Average annual rainfall in Delhi 611 millimetres (mm)
Total volume of rainwater harvested: 1890 cubic metre (m³), or
18,90,000 litres
This represents 55 per cent of the total water harvesting potential.
WATER SUPPLY SOURCE
A single borewell in the school is the main source of water supply.
The remaining requirement is supplemented by municipal water supply.
RAINWATER HARVESTING SYSTEM
Rooftop rainwater harvesting: Rooftop rainwater outlets are interconnected
through a network of pipes and collection chambers which lead to a
filtration-cum-buffer tank of 21,250 litres. The overflow from the
tank is diverted to a borewell of 200mm diameter and 30m depth to
facilitate recharging of the underground aquifer. The project was
implemented in May 2000. The cost of the entire rainwater harvesting
system was Rs 1.25 lakh.
| V.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.
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