Dipping water levels in dams ring alarming bells for City

Evaporation due to intense heat could bring storage to danger mark

Water level in the four major reservoirs in the Cauvery basin would come down by half due to evaporation, if the temperature continues to hover around 36 degree Celsius for the next three months.

This could lead to a severe water crisis in Bengaluru, Mandya and other places, says Dr G S Srinivasa Reddy, director, Karnataka State Natural Disaster Monitoring Centre (KSNDMC).

“The present storage in Harangi, Hemavathi, KRS and Kabini reservoirs, from where water is supplied to Bengaluru, is around 21 tmc ft. The water storage has declined due to lack of rainfall in 2015. The reservoir levels have reached their lowest levels in the last 40 years,” Reddy said on Wednesday.

Bengaluru needs at least 1.5 tmc ft of water every month and a total of about 3 tmc ft is pumped from these reservoirs to different places, including Mandya. However, a considerable quantity of the water in Kabini (6.87 tmc ft), Hemavathi (5 tmc ft), Harangi (1.5 tmc ft) and KRS (12.3 tmc ft) cannot be pumped due to two reasons: evaporation and dead storage level, he said.

Reddy said the shortage was due to monsoon deficit in 2015. During the southwest monsoon, the State as a whole recorded 635 mm of rainfall as against the normal of  839 mm, which is a 22% deviation. An amount of 178 mm of rainfall was recorded during the Northeast monsoon as against the normal of 188 mm - about 5% deficit, he said. Only 9% of the total 3,598 minor irrigation tanks had storage of more than 50%, while others were going dry, he said.

“The rainfall distribution in the State is highly erratic and even a small change in monsoon can lead to drought. Karnataka stands second only to Rajasthan in terms of the extent of arid and semi-arid areas. The State is highly vulnerable to drought as compared to its neighbouring states,” he said.

Reddy said that about 80% of the geographical area is prone to drought in Karnataka. “Groundwater levels are depleting due to successive droughts and quality of water is getting deteriorated. The data suggests that 12 out of the last 15 years (2002-2014), one or the other part of Karnataka has faced severe drought,” he said.