When the monsoons swept through Cauvery catchment area and the river overflowed, it was assumed that the State’s water position would perhaps be comfortable for an extended agricultural crop this year. However, barely six months later, the situation is back to square one, with reservoir water being stored primarily for drinking purposes, while a second crop of paddy in south Karnataka has been ruled out.

The “peculiar” position of the dwindling Cauvery reservoirs despite record-setting monsoon comes due to a failed monsoon. G.S. Srinivas Reddy, Director, Karnataka State Natural Disaster Management Centre, says the northeast monsoon brings with it nearly 55 TMC of water to the Cauvery reservoirs. This year, however, the deficiency has been 42.01% in these months.

Adding to this is the surprisingly low base inflows from catchment areas. “Normally, some of the monsoon rains seep into the hills and forests of the catchment areas, replenishes groundwater and the excess flows naturally in the months into the Cauvery. We are not seeing that this year at all,” says Mr. Reddy.

Decades of deforestation as well as excessive rains have removed the top soil, reducing the capacity of critical areas in Kodagu from absorbing water instead of letting it run-off directly into the river, he says.

Previously, Raj Bhagat Palanichamy, a GIS and remote sensing analyst with the World Resources Institute, had shown through satellite imagery that Harangi dam was filled with silt and debris that was washed down by the deluge.

A look at groundwater levels in 2018 shows that in the Cauvery catchment area, only Kodagu has seen falls in levels in the past year. Virajpet and Madikeri taluks, which bore the brunt of the deluge in the 2018 monsoons, have lost between 2 and 4 metres of groundwater.

In perspective, Raichur, which received 56% deficient rainfall — the worst in the State — has seen similar drops in groundwater as Kodagu which recorded, on average, 43% excess rainfall between June and September.

Not for crops

The reservoir levels are on a four-year high, with 44.6 TMC in four reservoirs. KSNDMC’s calculation shows that at least 12 TMC of drinking water is needed for urban centres till summer, while another 4 TMC is lost to evaporation or let off as natural flow of the river. With nearly 400 TMC released to Tamil Nadu, the State has released 150% of the amount mandated by the Supreme Court.

However, KSNDMC has told reservoir management committees that water cannot be used for agriculture. Paddy, for instance, would need another 70 TMC if a fresh crop needs to be grown. Committees have yet to take a decision on this.