The dry Palar riverbed near Palur village now has a new stone structure running across it. It is a dyke built by the Water Resources Department (WRD) to improve the flow of the river.
The waterway runs for a total distance of 243 km within Tamil Nadu and covers 60 km in Kancheepuram, before draining into the sea near Pudupattinam. Hundreds of wells sunk along the Palar riverbed, particularly below Palayaseevaram, feed several villages in Kancheepuram district and many areas in the southern suburbs of Chennai. Sustaining Palar river is of immense significance for areas such as Pallavaram and Tambaram as nearly 50 million litres of water is drawn from it for these areas.
While the river last witnessed floods in 2005 and has not had much flow for many years now, groundwater extraction has grown manifold on the Palar basin. This has meant fast depletion of the water table up to seven metres. Several residents depend on the river for cultivation. An official of the WRD said: “We decided to construct a dyke to tap the subsurface potential of the river that is necessary to recharge groundwater. The riverbed is between one and 1.5 km wide in Kancheepuram district.”
Unlike check-dams that ensure storage of water on the surface level of the river, the dyke will act as a dam at the bed level that locks the flood water seeping to the subsurface and draining into the sea. The dyke has been laid up to a depth of nine metres beneath the surface level to store nearly 300 million cubic ft of water.
According to WRD officials, the structure, built at a cost of Rs.16.83 crore, will have an impact on several villages, including Reddipalayam, Melachery, Palur, Devanur, Gurumanjeri, Seethanjeri and Arumbuliyur, for a radius of 5 km. Residents such as Ramu of Devanur village hope that the WRD’s initiative will help recharge the groundwater table at least by a few metres.
Welcoming the move, Kanchi Amudhan of ‘Palar Paathukappu Kootiyakkam’ (Federation for Palar Protection), says that more such facilities must be built on the river bed to harness rainwater. However, over-exploitation of groundwater by distilleries and packaged water units along the riverbank should be checked.
According to Palur panchayat president Shanthakumar the panchayat is able to maintain drinking water supply with available sources and the dyke will help in improving the supply.
Infobox
*Recharge structures of a similar nature have been built in other rivers too. They are, however, smaller in size.
*A dyke with a depth of four metres across the Vegavathi river at Mettukuppam, near Kancheepuram, has been constructed at a cost of Rs.22 lakh.
*Unlike the dyke in Palar river, which is a stone structure, a clay wall structure has been constructed across the Vegavathi river.
*Clay wall structure is also a good option to tap the subsurface water flow as it will not be weakened by undercurrents during floods.
*Kiliya river, a tributary of Palar river, now has a check-dam near K.K. Pudur to store water and improve the groundwater table.
