Delta yield dips due to depleting groundwater, industrial pollution

The proof to this alarming situation is the diminishing crop yield over the years. From an annual production of 35-40 lakh tonnes of paddy in the early 80s, the current yield has fallen to 25-27 lakh tonnes per year, threatening the food security of the state. 

Kalaivannan, a retired additional director, agricultural department, Thanjavur, said the inability to open the Mettur dam on the customary date of June 12, has really taken a toll on farming activities. 

“The Mettur dam, which caters to irrigation needs of the entire delta districts, is not being opened on the usual dates in January or June every year. Then the only source is the groundwater. But, this trend is dangerous as it will lead to a serious depletion of groundwater table,” he pointed out. 

Mannargudi S Ranganathan, general secretary, Tamil Nadu Cauvery Delta Farmers’ Welfare Association, revealed that in many areas, the groundwater level has gone down to an alarming 400-500 feet. 

“If we don’t act on a war-footing and put a stop to the depletion, even availability of potable water will become a big problem. If the situation continues like this, kuruvai (a paddy variety) will slip into history,” Mannargudi S Ranganathan cautioned. 

Ranganathan said, “There have been many treatment plants installed, but not many are interested in bearing the costs. As a result, these plants have been lying unused and water is untreated. There should be strict monitoring these industries.” 

In addition to the depleting groundwater levels, farmers also have to put up with the increasing pollution of the Cauvery River and its tributaries. “The river near Mettur Dam is extremely polluted but as it reaches the tail-end of the delta districts, the pollution is reduced, but not entirely gone. The major industrial units are taking the fresh water from Cauvery but releasing the effluents back into the river,” he said.

The depleting groundwater is also leading to increased top soil salinity due to the incursion of sea water. Kalaivannan added, “Earlier, the top soil salinity was only prevalent in Nannilam but it has reached almost 20 kms inland over the last few years.” 

As per the readings on Saturday, the level at the Mettur dam stood at 45.25 feet.The dam was receiving an inflow of 65 cusecs, while 1,200 cusecs was being discharged for drinking water needs.