NE monsoon effect: Tamil Nadu reservoirs see 23 tmc storage rise in 17 days

CHENNAI: Amid predictions for another spell of intense rainfall in the northern districts in the coming days, the State's water storage level is around 12% short of reaching its total capacity of 224.297 thousand million cubic feet (tmc).

As of Tuesday (December 17), the State's cumulative water storage stands at 195.455 tmc, 24.824 tmc short of the full capacity.

Heavy rainfall in various parts of the State over the past two and a half weeks during the active northeast monsoon phase has resulted in significant inflows into the State's 90 reservoirs. During this period, the water storage level increased by 10.68 percentage points, from 76.46% to 87.14%.

The State's cumulative water storage increased by 23.964 tmc during this time, up from 171.491 tmc on December 1.

The recent heavy downpours in Tenkasi, Theni, Virudhunagar, Ariyalur, Trichy, Karur, Pudukottai, and Ramanathapuram have further attributed to the sharp rise in the water storage levels of reservoirs.

A new system that developed over the Bay of Bengal on Monday is expected to bring heavy showers to the coastal districts from Chennai to Nagapattinam in the next couple of days, boosting the chances of further increase in storage levels.

As of Tuesday morning's report of the Water Resources Department (WRD), 12 reservoirs — three in the Coimbatore region, seven in the Madurai region, and two in the Chennai region — are at full capacity.

Storage in 18 reservoirs has exceeded 90% of their total storage capacity. Additionally, 23 reservoirs have water levels between 70% and 89%.

However, three reservoirs—Thumbalahalli in the Chennai region, Uppar Nirar in the Coimbatore region, and Uppar in the Tiruchy region—are at zero storage.

The State's largest reservoir, the Stanley Dam in Mettur, currently holds 97.51% of its capacity, amounting to 91.146 tmc out of its capacity of 93.470 tmc. According to the 8 am report on Tuesday, the reservoir has witnessed an inflow of 7,368 cusecs upstream and discharged 1,300 cusecs downstream.

The water storage level at Sathanur stands at 117 feet, just shy of its full reservoir level (FRL) of 119 feet.

Similarly, there has been a significant increase in storage in both system and non-system tanks across the State following torrential rains. Of the 14,140 tanks in 38 districts, 6,056 are now filled, while the water level in 3,165 tanks is above 76%.

Cyclone Fengal brought unprecedented rainfall on December 1 and 2 to many northern districts, leading to the rapid filling of tanks and water bodies. In Tiruvannamalai, 507 out of 697 tanks are now brimming, while 359 tanks in Tiruvallur (out of 578), 227 tanks in Kallakurichi (out of 336), and 460 tanks in Chengalpattu (out of 564) have also filled up.

"Due to breaches in bunds caused by Cyclone Fengal-triggered floods, several water bodies and tanks in the northern districts, particularly in Villupuram, have been damaged, leading to the release of water from numerous tanks. If not, the water level in many more tanks would have been stored to the optimum level," said a WRD official.

The department, however, took temporary measures to repair the damages caused by the cyclone and to cash in on the rainfall in the region during the monsoon season.

Torrential Blessing

– 90 reservoirs across the State

– 224.297 tmc total capacity

– 195.455 tmc cumulative storage as of Dec 17, reaching 87.14% of capacity

– 23.964 tmc rise in cumulative water storage level after Dec 1

– 14,140 tanks in 38 districts

– 6,056 tanks reached 100% of their storage as of Dec 17

– 2,720 tanks had 100% storage on Dec 1