Groundwater is being over-exploited in more than 30 percent of the areas

Chennai: Of the 1,202 firkas surveyed by the water resources department for groundwater use, a total of 57% have been classified as over-exploited (395, about 30%), semi-critical (227) or critical (64). A firkas (or revenue blocks) is a group of revenue villages.

According to the WRD’s assessment report, firkas are classified as over-exploited if the stage of groundwater extraction (SoE), a measure of annual groundwater extraction over the annual extractable groundwater resource, is 100% or more. This means that extraction exceeds the capacity to recharge. Firkas are classified as semi-critical if SoE is 70% to 90% and as critical when it is 90% to 100%.

Expressing concern over 395 firks being classified as over-exploited, the farmers have requested that the state government take measures to prevent groundwater exploitation keeping in mind future requirements.

KV Elankeeran, president of the Cauvery Delta Farmers Association, told TNIE, “Historically, the state has had many ponds, lakes and connecting channels and canals. Excess rainwater used to naturally flow into nearby lakes and tanks during the rainy season through designated channels. But nowadays most of the water bodies and their surrounding areas have been encroached upon. There is no way for the water to flow out logically.”

“To avoid groundwater exploitation, the state should increase rainwater harvesting and create awareness. More check dams should also be constructed to improve groundwater recharge.”

K Subramanian, state general secretary of the Tamil Nadu Farmers Association, urged the state to identify and restore the lost channels.

“The 1202 firks have been classified into five types: overexploited, critical, semi-critical, safe and saline or poor quality, based on groundwater level, rainfall and groundwater use,” a senior official of the water resources department told TNIE. The water resources department has installed around 900 digital groundwater level recorders to continuously monitor the water level. He said steps are being taken to install these devices in all the 1202 firks. “To improve the groundwater level, check dams will be constructed at 10 locations in the Cauvery and Vaigai basins, while the water resources department is planning to construct subsurface dams in the tail-end areas of the Cauvery basin. This will also prevent seawater intrusion. The work will begin as soon as the government issues orders,” he said.