Nine days after closure, floodgates of city’s Red Hills reservoir reopened

After nine days, the floodgates of Red Hills reservoir were reopened on Friday as inflows increased following heavy overnight rainfall in catchment areas. Similarly, more water was discharged from two other drinking water reservoirs in the city as their storage rose rapidly since Thursday night.

Officials of the Water Resources Department said the shutters of Red Hills reservoir, which were opened during the first spell of Northeast monsoon in mid-October, were closed on October 29 owing to a drop in inflow.

“We had to open the shutters for the second time this season as the storage increased to 2,970 million cubic feet against its capacity of 3,300 mcft on Friday,” an official said.

With flood run-off from upstream areas, the WRD stepped up water discharge from the initial 200 cubic feet per second (cusecs) to 500 cusecs on Friday evening as a precautionary measure. The reservoir also received its share of inflow from the Poondi reservoir.

The WRD has issued a flood warning to areas downstream such as Puzhal, Kosapur, Manali and Sadayankuppam, advising residents to move to safer locations.

Rise in inflow

Though the floodgates of Chembarambakkam and Poondi reservoirs have remained open since mid-October to release minimal quantities of water, the release was increased on Friday due to a rise in inflow from their catchment areas.

Poondi reservoir’s shutters were opened wider to release 2,000 cusecs of water as it continued to receive floodwater from various waterways and storage structures upstream, and the Ammapalli dam in Andhra Pradesh. Similarly, the release from Chembarambakkam reservoir was increased from 100 cusecs to 300 cusecs on Friday to maintain the water level at 22 feet.

According to officials, such controlled water release was planned to ensure flood buffer space in reservoirs during extreme weather events and prevent flash floods. The five reservoirs currently hold a combined storage of 10,052 mcft, which is 86.54% of their total capacity.