CHENNAI: Endangered
Urban Tanks
Water has always
been a scarce commodity in Chennai. The situation today is so
appalling that water supply has been restricted to every alternate
day. It started deteriorating after the last three consecutive
drought years.
Water supply for Chennai city was first designed in 1872 to
meet the demands of a population of 0.47 million by the then
special executive engineer to the government, Fracer. The flow
from Kortalliar river was diverted to Cholavaram and Red Hills,
which were connected to the city through channels. It supplied
32 million litres per day (mld) of water to the city. The supply
was supplemented by 159 mld from the Poondi reservoir in 1944.
The capacity of Red Hills and Cholavaram was increased in the
late 1960s. The projected demand for the year 2001 is 283 mld.
The city's main source of water is the Red Hills lake, with
a total capacity of 3,000 million cubic feet. The total capacity
of Poondi, Cholavaram and Red Hills reservoirs is 6,000 million
cu ft. The water from these three sources has been completely
diverted from irrigation to supply for domestic and industrial
needs.
Tank
system
Tamil Nadu has as many as 39,202 tanks, out of which about
124 tanks are in the chennai Metropolitan Area (MMA). The
tanks have a waterspread area of approximately 5.5 per cent
of the MMA area (waterspread area is 63.8 sq km, and MMA area
is 1,167 sq km). In addition, there are 39 temple tanks in
the city. A tank restoration scheme was launched in the city
in 1883 on the recommendations of the Famine Commission. Under
the scheme, a memoir detailing the hydrological features was
drawn up. Most tanks in the area form 'system eris' or tanks
which are a part of integrated water harvesting systems, and
are situated in the basin of one of the four rivers flowing
through the area.
But urbanisation has taken its toll - the stormwater courses
feeding these tanks have disappeared and water flows into
the sea without filling these tanks.
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