Despite excessive rainfall, groundwater depletion in TN

Excessive rainfall during the southwest monsoon may have helped Tamil Nadu farmers prepare for the crop season, but it did not improve the abysmal groundwater levels in 25 districts, raising serious concerns over the availability of drinking water in the state.

A recent weather department record showed that 29 out of 32 districts have reported surplus and moderate rainfall, but the PWD department’s State Ground and Surface Water Resources Data Centre report for August 2017 has revealed groundwater levels in as many as 30 districts have dipped compared to last year.

19% deficit rainfall
Tamil Nadu reported deficit rainfall of 19% during last year’s southwest monsoon, which sets in in June and lasts until the second week of October. During this year’s monsoon season, Coimbatore received 246.4 mm rain since June, as against the average of about 120 mm, the highest in the state.

However, groundwater in the region dipped to about 18.02 m below the ground level, as against levels seen in the same period last year, which was 14.31 m.

Chennai revealed a similar anomaly.

While it reported excess rain, its groundwater levels plunged by 3.04 m compared to the same period last year.

Delta districts fare poorly
Trichy and Tiruvarur delta districts, described as the rice bowl of Tamil Nadu, too, fared poorly in terms of groundwater depletion, recording a decrease of 4.70 m and 0.55 m, respectively.

However, groundwater levels marginally increased by 0.72 m and 1.12 m in Thanjavur and Ariyalur districts of the state.

A senior PWD official attributed poor groundwater levels to a lack of harvesting facilities in rural areas.

The official said that keeping in view the concerns regarding the problems of over-exploitation of groundwater resources in the state as well as to ensure sustainable Water Resource Management and assured irrigation facilities in the affected areas, a scheme on artificial recharge to groundwater through dug wells has been prepared.

More than 12.5 lakh of the existing dug wells for irrigation are to be taken for recharging groundwater, he said.