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FAVOURABLE
RECHARGING ZONES IN CHENNAI
CITY
1.
Rain Water Harvesting is indispensable for Chennai
City as the city residents are facing acute water
shortage during summer months, every year. As the
Chennai City receives sufficient rainfall during North
East monsoon, availability of surface water is abundant.
However it is not sufficient during other periods
especially during summer months.
2. The
overall surface formation is alluvium followed by
considerable thickness of sand with admixture of clay,
the city's terrain condition is highly suitable for
rain water harvesting. The slope of Chennai city is
also very gentle.
3. About
17 locations are identified for augmenting rain water
harvesting, covering mostly sandy aquifer zones i.e.
lithologically homogeneous. The identified 17 locations
as indicated in the adjoining map is based on available
hydrogeological and geophysical data. The sub-surface
formation is mostly sand with little clay admixture.
4. Apart
from the above identified locations, the unmarked
areas has the lithology of heterogeneous formation
which is not very much condusive for Ground water
recharging. However, selected pockets to be identified
by geophysical survey, can be tried for rain water
harvesting for small quantum of recharging. The exact
site or point of rain water harvesting within the
identified location has to be ear-marked after conducting
suitable geophysical investigations and considering
other related hydrogeological parameters.
5. The
South Eastern part of the Chennai City, namely Aadambakkam,
St.l Thomas Mount, Aalandur, Velachery, Tharamani
and part of Guindy, Medavakkam and Perungudi is predominantly
layered by crystalline rock formation, which is generally
of impervious nature and hence these areas are not
favourable for rain water harvesting.
6. The accompanying statement
shows the thickness of saturated and unsaturated aquifer
zones in different locations of Chennai city for preliminary
selection.
Map of Aquifer
zones for favourable recharging groundwater by rainwater
Harvesting in Chennai city.
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