Water to be released from Poondi reservoir on September 25 evening, much ahead of NE monsoon

Open Poondi reservoir to discharge 1,000 cusecs of water to Cholavaram reservoir. Tiruvallur district issues flood warning to people living near Kosasthalaiyar river. Water will be used to fill Cholavaram reservoir and recharge checkdams. Chembarambakkam reservoir opened in June due to unusual rains. Five water bodies used for city water supply have 70% of capacity. Chennai has enough resources for daily water supply.

The shutters of Poondi reservoir will be opened on Monday (September 25) evening to discharge water, much ahead of Northeast monsoon, which provides major share of rains. However, water released from the reservoir will be diverted to Cholavaram reservoir.

Following heavy rains in catchment areas of Kosasthalaiyar river in this Southwest monsoon, the Water Resources Department (WRD) has decided to release 1,000 cubic feet per second (cusecs) water from two flood gates of Poondi reservoir around 4 p.m. on Monday. The water level has touched 33.90 feet, just one feet lower than its full level as the reservoir received a flood runoff of about 1,520 cusecs around 6 a.m.

Water discharge from city reservoirs is more common during the ensuing Northeast monsoon. Spread over 34.58 sq.km. in Tiruvallur district, the reservoir, which is one of the prime water bodies used as Chennai’s drinking water sources, now has a storage of 2,792 million cubic feet against its capacity of 3,231 mcft.

Tiruvallur district administration has also issued a flood warning to people living in low level areas along Kosasthalaiyar river such as Krishnapuram, Beemanthoppu, Tamaraipakkam, Pudukuppam, Napalayam, Idayanchavadi, Manali, Sadayankuppam and Ennore.

Officials said the water discharged from Poondi reservoir into Kosasthalaiyar would not be drained into the sea. It would be instead used to fill up Cholavaram reservoir, which has only minimum storage. Water would be diverted from Tamaraipakkam anicut through a 13-km upper supply channel to Cholavaram.

Moreover, water discharged would also be used to recharge 4-5 checkdams located downstream of Poondi and across Kosasthalaiyar river. “This will help maintain the river regime-the annual variation in amount of water during different seasons. Discharge of water will help smooth flow during heavy floods in future,” said an official.

The reservoir is expected to receive more inflow, given the heavy rains in catchments like Tiruttani that experienced heavy rains of 13 cm on Saturday, September 23. A minimum discharge would be maintained even after drop in inflow, the official added.