The Water Resources Department will start work on construction of a check dam in Vayalur, Kancheepuram district, by February-end. The nearly three-decade-old proposal has been revived to tackle seawater intrusion and augment supply for various drinking water schemes.
The ₹32.50-crore project to construct the check dam at the tail-end of the Palar river was recently approved by the Indira Gandhi Centre for Atomic Research, Kalpakkam, which is funding the work.
WRD officials said this would not only help supply water to Department of Atomic Energy establishments like IGCAR but also recharge the water table.
Though WRD gave an assurance to supply 27 million litres of water a day, only half that is being supplied now.
Water for agriculture
The check dam — 1,190m long — would help retain the floodwater that would otherwise flow into the sea. “We will have an additional storage capacity of up to 1,500 million cubic metres with two fillings. Nearly 330 hectares of agricultural lands would benefit through the scheme,” an official said.
The department has planned to build a check dam with a subsurface dyke based on the observed maximum water level in 2015.
The structure with a height of 1.5m would help store more floodwater in the river and recharge the water table.
The sub-surface dyke or subsurface wall to be built for a depth of 8m would prevent seawater intrusion and enhance the groundwater recharge in the aquifer, officials said.
The conventional check dam design would not serve the purpose due to its proximity to the sea and backwaters. The water stored and recharged through the innovative design could be used for domestic and agricultural purposes in the surrounding areas, the officials said.
Subsurface dyke
A similar subsurface dyke with bed dam was constructed in Palar river at Palur in Chengalpattu Taluk in 2014 and it has helped in groundwater recharge. On the potential to augment Chennai’s water supply, a separate project needs to be chalked out to transport the water.
The project is expected to be completed by March 2020.