It’s been almost a month since the peak rainy season has ended over Chennai and peripheral region. Yet, Poondi reservoir, the prime water source of Chennai’s water supply, continues to receive considerable inflow from catchment areas and had its shutters open till Thursday.
The Northeast monsoon, which unusually prolonged till January 27, is cited to be one of the factors for steady inflow from Kosasthalaiyar river and Nagari and Nandiyar rivers. The Water Resources Department (WRD) expects the inflow to continue till February first week.
The reservoir, which had scarce storage until the start of monsoon, is now filled to its brim. Its storage is being maintained at 100% and surplus of 450 cubic feet per second (cusecs) is being released into the Kosasthalaiyar river.
For the fifth consecutive year, water was let out from the reservoir during NE monsoon. What made it unusual this year was water discharge has continued almost till fag end of January.
Officials of the WRD said groundwater had saturated following peak rainfall season and floodwater generated from catchment areas like in Tiruttani flowed into Poondi reservoir. They recalled that Krishna water from Andhra Pradesh and floodwater received in the water body was diverted to other water bodies to step up total storage to 10,442 million cubic feet. This is 82% of their combined capacity.
“We also replaced two sand vent shutters that remained unused for many years by transferring water from the Poondi reservoir. These shutters that are deeper than the other floodgates will prevent sedimentation in the lake area and help improve storage,” said an official.
While shutter gates were opened in January since 2021, water discharge was stopped by mid-January. This time, the flood gates of the reservoir remain open for more than a month. With rapid changes in the inflow pattern and more floodwater in city’s reservoirs beyond peak monsoon period, water experts noted that there was a need to invest in more projects to conserve resources.
WRD sources said proposals are awaiting the nod of the State government to raise the height of the reservoir by two feet to add water storage of 780 mcft. Another proposal to create another reservoir at Ramanjeri is also under investigation. There is also potential to construct more check dams both in upstream and downstream portions of Poondi reservoir to conserve resources and prevent from draining into sea.
Published – January 31, 2025 01:10 am IST