The overnight downpour in the catchment areas brought copious inflow into the city reservoirs and boosted their storage which had been dipping.
The three major reservoirs, which largely sustain drinking water supply to Chennai, received good rainfall. Chembarambakkam, with 9 cm of rainfall, received the highest, followed by Poondi with 7 cm. Within a few hours, the heavy rains added 103 million cubic feet (mcft) of water to the storage in the lakes, enough to supply the city for four or five days.
The Chembarambakkam lake received a maximum inflow of nearly 700 cubic feet of water per second from its catchment areas, including Nemam. Though Poondi lake is receiving about 190 cusecs of Krishna water, much of the inflow was from the catchment areas. A major share of the inflow into the lake was diverted to the reservoir in Red Hills, which recorded the least rainfall of 2 cm.
Officials of the Water Resources Department said the rains had also prevented loss of water due to evaporation and helped maintain the water bodies’ storage at the same level.