CHENNAI: Tamil Nadu has made up most of its rainfall deficit in less than a month, as an unusually wet start to the northeast monsoon erased a 16% shortfall left by the southwest monsoon, according to data from the commissionerate of revenue administration and disaster management’s TNDRRA.
By Tuesday, cumulative rainfall in the state since June 1 was less than 1% below normal. Of the 23 districts rain deficient on September 30, 18 are now normal or in excess. October’s downpours drove the turnaround.
Between October 1 and 27, the state averaged 217.2 mm against a normal of 144.2 mm, a surplus of 51%. All 38 districts recorded normal, excess or large excess rainfall during the period.
The sharpest gains came in districts that began October with deep deficits. Tiruppur swung from -40% to +13%, Kallakurichi from -29% to +2% and Erode from -32% to +6%.
Nagapattinam improved from -54% to -8% and Karur from -53% to -6%. Others that narrowed shortfalls without closing them are Tiruchy (-39% to -7%), Namakkal (-42% to -8%), Mayiladuthurai (-28% to -6%) and the Nilgiris (-32% to -13%).
Several districts far exceeded October norms. Chennai recorded 289 mm of rainfall - 33% above its October-to-date normal.
Dr B Chandra Mohan, commissioner of revenue administration, urged caution. “Rainfall received across a district may vary considerably, including in reservoir catchments,” he said. “A narrowing rainfall deficit therefore does not, by itself, establish a corresponding improvement in groundwater levels or stored water.”
The latest figures, he said, “mark a significant change in the state’s rainfall position, rather than the conclusion of the season’s rainfall needs”.