Even a small pond can make a difference to the quality of groundwater that is at present, grossly affected by sea water intrusion. This is one of the plans proposed by the Department of Geology, Anna University, as part of a pilot study to restore the aquifer in northern localities along the coastline.

The study is being implemented in localities up to a radius of 28 km, including Minjur, Ponneri and Panchetti, and has found that sea water has intruded up to 7 km. Samples taken from some parts of Minjur show that groundwater continues to have a high total dissolved solids (TDS) level, which is used to determine salinity. The TDS level is nearly 2,500 mg/l against the permissible limit of 500 mg/l.

Construction of check-dams, which are structures built across Araniar and Kosasthalaiayar rivers in Tiruvallur district to store surface water, has helped bring down the high chloride content by half – from 600 mg/l recorded two decades ago. Normally, chloride content must not exceed 250 mg/l in groundwater used for drinking, professors at the Department of Geology, Anna University, said.

To arrest seawater intrusion, a team of five research scholars who are working on a European Union-funded collaborative research project, are creating a pond in Andal Madam near Pulicat. The pond, which will span only 400 sq.ft. and have a depth of 1.5 metre, will be created to assess the impact of rainwater percolation intogroundwater.

“We are planning to install an automatic weather station, which will measure rainfall and other equipment to measure the level and quality of groundwater . This will help us understand the change in quality and prevent further intrusion of seawater,” said L. Elango, a professor at the department. The department also plans to create awareness among farmers to dig small ponds in their lands to improve groundwater quality. The recommendations of the pilot study will be submitted to the State government. The department is also studying the impact of a check-dam in Periyapalayam, Tiruvallur district, on the groundwater in villages largely dependent on irrigation.

On Thursday, the department joined hands with the National Geophysical Research Institute, Hyderabad and Association of Hydrologists of India to honour former Vice-Chancellor of Anna University V.C. Kulandaiswamy for his contribution to hydrology. “Water must be made national property to achieve the dream of interlinking of rivers. Transmitting surplus water to drought areas is essential to address water crises,” said Mr. Kulandaiswamy who delivered a lecture on interlinking of Indian rivers.

Pointing to the lack of political will among States that had surplus water, which otherwise gets drained into the sea, he said interlinking of rivers would remain on paper unless water is made national property. Construction of reservoirs and check dams is necessary to ensure sustained water availability for food production in the State, he added.

The department plans to create awareness among farmers to dig small ponds in their lands to improve groundwater quality