Signs of monsoon revival: Storage capacity in Cauvery basin reservoirs still an area of concern

Monsoon revival in Cauvery basin brings hope of increased storage in major reservoirs, but current levels remain low. Harangi nearing full capacity of 8.50 tmc ft, KRS 17.05 tmc ft (34%), Hemavathi 19.75 tmc ft (53%), Kabini 2,275.49 ft (FRL 2,284 ft). Cumulative storage of four major dams in basin at 58.57 tmc ft (51%). Rainfall deficit in catchment areas.

Not withstanding the signs of monsoon revival in the Cauvery basin, especially in Kodagu and parts of Chikkamagalur, concerns remain over the storage positions in the major reservoirs.

While Harangi is nearing its full reservoir level of 2,859 feet, the gross capacity of the dam is only 8.50 thousand million cubic feet (tmc ft).

With respect to Krishnaraja Sagar (KRS) in the downstream, the inflow increased to 9,514 cusecs on Sunday, July 23, shoring up hopes that the water level would increase. But for this, the Cauvery catchment should receive copious rains as at Bhagamandala, which recorded 238 mm of rainfall during the 24-hour period ending 8.30 a.m. on Sunday. A one-off rainy day will not help sustain the inflow which during peak monsoon has crossed 100,000 cusecs in the past. The gross storage capacity of the KRS is 49.45 tmc ft. against which the storage on Sunday, was 17.05 tmc feet which is 34 per cent of its actual capacity.

Similarly, Hemavathi at Gorur in Hassan is another large dam which has a storage capacity of 37.10 tmc ft. But, the storage on Sunday was 19.75 tmc ft. which is 53 per cent of its actual capacity. The FRL of Hemavathi is 2,922 feet but the reservoir level on Sunday was 2899.96 feet.

The scenario, with respect to Kabini, is relatively better but the reservoir is yet to attain the full reservoir level (FRL) of 2,284 feet. It is the first dam to attain the FRL during monsoon as the catchment area of the river is in Wayanad region of Kerala where the monsoon reaches earlier than Karnataka. But this year the catchment areas had deficit rains. The reservoir level of Kabini on Sunday was 2,275.49 feet and the rate of inflow was 13,114 cusecs raising hopes of the dam attaining the FRL in the days ahead.

The cumulative storage capacity of the four major dams in the Cauvery basin in Karnataka is 114.57 tmc feet against which the storage on Sunday was 58.57 tmc ft. which is 51 per cent of the actual capacity. The cumulative storage on the same day last year was 112.68 tmc ft. which underlines the rainfall deficit in the catchment areas of the rivers.