By improving the capacity of two tanks near Minjur, the government aims to create another reservoir for the city.
According to Water Resources Department officials, the two tanks are in Kattur and Thataimanji near Minjur — nearly 35 km from Chennai.
The WRD project aims to not just augment Chennai’s water supply but also resolve drinking water issues in the Minjur region, which has been grappling with the challenge of seawater intrusion.
WRD plans to increase the storage capacity of the tanks, spread over 615 acres, by raising the height of the bund.
Unlike the upcoming Thervoy Kandigai-Kannankottai reservoir, where a common bund is being put up, WRD officials said that the height of the bund in the adjoining tanks would be raised to 7.1 m.
The storage capacity of the tanks is expected to increase from 58.27 million cubic feet (mcft) to 350 mcft. Nearly 1,700 mcft of surplus water is drained into the sea, every year, through the Araniar river, even after filling up the tanks, an official pointed out.
There are plans to convey water stored in the tanks to the nearest Metrowater pumping station. It may be recalled that Chennai Metrowater has not drawn from its Minjur well fields for several years now.
The sluices and regulators will be reconstructed. The carrying capacity of the channel conveying surplus water from the Araniar river to the Kattur tank will also be improved.
Moreover, the State government has also approved a proposal to construct a combination of check dam and sub-surface dyke across the Araniar river, in Andarmadam, as part of the ₹65-crore project.
Officials say that though groundwater is available at a depth of 2-3 m, it has turned saline. The storage structures will serve purposes of arresting seawater intrusion and groundwater recharge. The WRD has sought the support of IIT-Madras to design the structures. It plans to begin the project in three months with funding from the State government and NABARD.
In Minjur, several farmers continue to depend on the tanks for paddy and groundnut cultivation. According to a study by the Department of Geology, Anna University, seawater has intruded up to 14.7 km in the Minjur-Panchetti belt, over a length of 20 km along the coast.
Prof. L. Elango of the Department of Geology said instead of direct intervention in the affected region, the government must focus on groundwater recharge in the areas that have seen seawater intrusion. This would help improve water quality and flush seawater back to the sea.
