Rise in inflow from Krishna River boosts water level in Chennai's reservoirs

CHENNAI: Chennai's drinking water reservoirs are experiencing a rise in water level due to increased inflow from the Krishna River, said a Daily Thanthi report. The city’s primary water sources are Poondi, Puzhal, Chembarambakkam, Cholavaram, and Kannankottai-Thervoy Kandigai; and they have a combined aggregate capacity of 11.757 tmc (thousand million cubic feet).

As per water sharing agreement, Andhra Pradesh is expected to release a total of 12 tmc of water annually to Tamil Nadu's Poondi reservoir --- 8 tmc from July to October and 4 tmc from January to April. The water reaching Poondi is then redirected to reservoirs like Chembarambakkam and Puzhal to meet Chennai’s water supply needs.

This year, summer caused severe depletion in Poondi’s water levels, prompting Tamil Nadu officials to request water release from the Kandaleru Dam in Andhra Pradesh. Since September 19, water has been released from Kandaleru to Poondi, initially at 500 cubic feet per second (cusecs), which was later increased to 1,000 cusecs.

However, the onset of the northeast monsoon brought heavy rains in the Poondi catchment area, leading to a temporary reduction in the water release from Kandaleru to 500 cusecs. Then there was a pause in rainfall, following which the water release was increased to 1,000 cusecs.

Yesterday, Krishna water was released to the Poondi reservoir at 500 cusecs. This water is then routed to Chembarambakkam dam, further raising its level, while Puzhal reservoir remains stable due to the increased supply of Krishna water, the report added.

Currently, Chennai's reservoirs collectively hold 41.4% of their capacity, bolstered by 791 tmc of Krishna water inflow, sufficient to meet the city’s drinking needs for about 20 days. With Kandaleru Dam currently holding 43.20 tmc out of its total 68 tmc capacity, officials anticipate an additional 2 tmc of Krishna water this year to further supplement Chennai’s requirements.

According to the Water Resources Department, the capacity of the Poondi reservoir stands at 3.231 tmc, with 476 mcft (million cubic feet) currently available. Officials are managing the water flow from Poondi to Chembarambakkam at 350 cusecs while the Chennai Metropolitan Water Supply and Sewerage Board receives 17 cusecs through the baby canal. Chennai typically requires 3-4 tmc of water annually, and hence, the anticipated additional 2 TMC from Krishna this year will help meet the city's current needs, with further evaluations to follow as necessary, officials said.