Subsurface water flowing into sea can parch coastal areas: Researcher

Speaking to DT Next about the research that he had commenced about four months ago, Selvam said, “Not many are aware of the subsurface drinking water intrusion happening in coastal areas. This is happening at an alarming rate. If it is not arrested, coastal villages will not have water for drinking and agriculture in future.”

For his research, Selvam chose the area from Rameswaram to Manapad in Thoothukudi. Initially, he had chosen spots including Manapad, Valli cave in Tiruchendur, Punnakayal, Valinokkam and few pockets in Rameswaram to check subsurface water intrusion to sea.

“We have fixed seepage meters in the spots to check whether this is happening. Samples will be tested for salinity and electrical conductivity. If these parameters are less, we can assume that intrusion has happened,” said Selvam.

Some parts of subsurface have radon, a radioactive element. If it is found in seawater, that is another indication. Similarly, the nutrient content of the seawater would also be checked – if it is high, it is yet another evidence, he added.

This phenomenon occurs at different levels at various places. For instance, the intrusion happens at 20 feet below ground level at Valinokkam, while it is 10 feet at Tiruchendur.

When asked about the measures to prevent this, Selvam said barriers like ring wells and underground barriers can be constructed. “Water from the barriers can be supplied to the coastal villages,” he said.

According to him, Nalla Thanni Theevu (Drinking water island) in Thoothukudi was the best example for the phenomenon. “The island was named for the drinking water availability. But due to subsurface water intrusion phenomenon, it lost all the groundwater and only saline water is available now,” said Selvam.

After he got the approval for the study, a professor from Kanniyakumari and another from Chennai have applied for carrying out a similar research in those coastal areas.