Another source will be added before this northeast monsoon to bolster storage at the Chembarambakkam reservoir, one of the major sources of water for Chennai.
Nearly 80% of the reconstruction of the British-era Korattur check dam across the clean stretch of the Cooum in Tiruvallur district has been completed. Built in 1879, the check dam with regulator was damaged during the 2015 floods.
Officials of the Water Resources Department said the check dam had been designed to discharge 30,000 cusecs (cubic feet per second) of flood water, taking into account the heavy flow in the river six years ago.
The 4 m tall structure across the river (140 m wide), can store 10 million cubic feet of water. It would retain flow in the river for 3 km upstream for an additional three months after the monsoon.
This would not only help in recharging the groundwater, but also meet the drinking water and irrigation needs of the surrounding villages such as Jamin Korattur, Gudapakkam and Puduchatram. With a sandy layer of 30 feet depth, groundwater percolation would be effective in the locality.
The offtake regulator, with 12 shutters, is being renovated to transfer surplus water from the river to the Chembarambakkam reservoir. About 3,600 cusecs of water can be released through the regulator. Excess water from the Cooum can diverted to the reservoir through the 7 km-long New Bangaru Channel. Besides its own catchment areas in the Adyar sub basin and the transfer of Krishna water from Poondi reservoir, the Chembarambakkam reservoir would get Cooum water through this arrangement, the officials said.
Water can also be diverted to the Thiruninravur tank as a supply channel is linked to the waterbody.
On Tuesday, a team of officials inspected the site where the fourth storage structure in the river is being rebuilt. The remaining work includes building the body wall of the structure and the flood protection wall. Savudu or coarse soil from Thiruninravur tank is being brought to form the river embankment for a height of 6 m and a length of nearly 1.7 km.
The ₹32 crore project was taken up earlier this year with funding from NABARD (National Bank for Agriculture and Rural Development). There was a delay in executing the project due to issues in finding financial assistance. The work is expected to be completed by September-end, officials said.