Shutters of Red Hills reservoir opened for fourth time this monsoon to create flood cushion

Shutters of the Red Hills reservoir, one of the key drinking water sources of Chennai, were opened for the fourth time this monsoon on Friday to maintain an adequate flood buffer. This follows forecast on possibility of heavy rainfall over Chennai and its surrounding districts on November 17.

The Water Resources Department initially released about 300 cubic feet per second (cusecs) of water on Friday afternoon and stepped up the discharge to 600 cusecs later by evening. The WRD officials noted that the measure was being taken to regulate the inflow and outflow and balance a healthy storage in the reservoir.

At present, the storage in the reservoir stood at 2,900 million cubic feet (mcft), which is nearly 88% of its capacity. “We want to maintain the water level at 19 feet and bring down the storage by 6% – 7% to accommodate heavy inflow during intense downpour in the coming week and reduce the possibility of flooding in the downstream areas,” said an official.

While a minimal water discharge in two other reservoirs — Chembarambakkam and Poondi — has been maintained during this monsoon, the Red Hills reservoir has required frequent shutter operations. Officials noted that water discharge was regulated based on the inflow, and the shutters of Red Hills reservoir were closed whenever inflow dropped.

Nearly 600 mcft of floodwater has been let into the surplus course, which joins the Ennore creek, since the first time the floodgates were opened on October 15.

The Regional Meteorological Centre has forecast heavy rainfall to return from November 16 under the influence of an upper air cyclonic circulation that lies over south Sri Lanka and adjoining southwest Bay of Bengal.

While delta districts will initially receive intense showers on Sunday, more northern districts, including Chennai, Tiruvallur and Cuddalore, have chances of heavy downpour on Monday. Isolated heavy rainfall may continue over Tiruvallur, Ranipet, Tirunelveli, Thoothukudi and Kanniyakumari districts on November 18.

In its outlook, the RMC has also forecast possibility of a low pressure area to form over the southeast Bay of Bengal around November 21.