Chennai, Dec 14
Copious rainfall during the northeast monsoon and sustained inflows in the Cauvery river system have significantly improved water storage across irrigation tanks in the Cauvery delta, offering major relief to farmers ahead of the peak agricultural season.

Of the 764 irrigation tanks in the delta region, 386 have now reached full capacity, a sharp rise from just 42 tanks recorded three months ago. In addition, 329 tanks have filled beyond 75 per cent of their capacity, underscoring the extent of the recovery in water availability across the agrarian heartland of Tamil Nadu.

The delta districts of Thanjavur, Tiruvarur, Mayiladuthurai and Pudukkottai together account for 737 system tanks fed by rivers and canals, in addition to rainwater, along with 27 non-system tanks dependent entirely on rainfall.

Thanjavur district has the highest concentration of irrigation tanks at 561, followed by Pudukkottai with 170. Tiruvarur has 28 tanks, while Nagapattinam and Mayiladuthurai have three and two tanks, respectively.

A majority of these tanks are located in tail-end areas and play a crucial role in supporting paddy cultivation, particularly during the samba season.

Typically, these tanks receive substantial inflows during September and October. However, this year saw an early rise in storage levels, with many tanks crossing the 50 per cent mark by the end of August itself. This was largely due to the continuous flow of water in key channels such as the Grand Anaicut and Vennaru, coupled with the timely release of Cauvery water from the Mettur dam on the customary date of June 12. Since then, the Mettur reservoir has reached full storage level on seven occasions, aided by surplus releases from Karnataka.

Adequate rainfall during the southwest monsoon in Thanjavur district, followed by above-normal rainfall during the northeast monsoon between October 1 and December 11, further strengthened water availability across the delta.

As of now, apart from the 386 tanks at full capacity, another 337 tanks hold water between 75 per cent and 99 per cent of their capacity. Thirty-one tanks have storage levels between 50 per cent and 75 per cent, while only five tanks remain in the 25 per cent to 50 per cent range. The improved storage is expected to support standing samba crops, ensure water availability for livestock during the summer months, and contribute to a rise in groundwater levels across the region, reinforcing overall water security in the Cauvery delta.

Water storage in TN's Cauvery delta tanks increases as rain boosts water storage