The proposed check-dams across the Araniar and Kosasthalaiyar rivers in Tiruvallur district will help in augmenting water supply to Chennai. They will also help in recharging groundwater in the areas near the rivers, according to officials in the Water Resources Department (WRD).
Of the Rs.550 crore allocated towards artificial recharge in rivers and streams across the State, nearly Rs.48 crore would be utilised by the WRD, Chennai region, towards providing check-dams in the rivers to prevent runoff of rainwater into sea. The locations for establishing facilities were selected using remote sensing technique.
Officials of the WRD said the project would facilitate increase in the water table in six well fields used for city water supply. Work on constructing a check-dam at Paleswaram near Periapalayam across the Araniar river, at a cost of Rs.7.40 crore, would be completed next month.
Provision of three check-dams across the river has been recently approved at a total cost of Rs.12.90 crore. The facilities would come up in Kalpattu, Sengathakulam and Panapakkam, all near Uthukkotai. A check-dam worth Rs. 3.66 crore would be raised at Vannipakkam near Cholavaram on the Kosasthalaiyar river.
Work on these facilities is expected to commence in April. The project would be taken up in a phased manner. A check-dam at a cost of Rs.7.50 crore would be provided at A.Reddypalayam near Minjur next year where seawater intrusion is intense, an official said.
Provision of check-dams would help in replenishment of groundwater, which has dropped below 10 m in various locations in Tiruvallur district. “We are monitoring water level and quality by taking samples from wells within a few km radius before and after the project,” an official said. In Paleswaram, the water table is below 15 m now.
Chennai Metrowater officials, however, said it would take a longer duration for the benefits of check-dams to be realised in most of the well fields as they are located away from the Araniar river.
The average water level in the well fields is below 20 m. About 20 million litres a day are drawn from well fields at Tamaraipakkam, Poondi and Minjur for city supply.
The well field in Panchetti, where drawal was stopped several years ago, could be used again after the completion of the project. More check-dams must be provided in the Kosasthalaiyar river for better groundwater recharge in the well fields, they said. WRD officials said proposal would be chalked out to provide additional facilities in the Araniar-Kosasthalaiyar basin in the coming years.
