Release of excess water from dams led to Kodagu landslides, says govt

BENGALURU: Excess water released from dams in the Cauvery Basin led to the devastating landslides that buried the northern parts of Kodagu and Malnad, the state goverrnment has told the Centre.
As part of its 137-page report submitted to the Centre and Prime Minister Narendra Modi, the Karnataka government said excess water due to heavy rain in the Cauvery catchment areas resulted in all four dams of the basin reaching their maximum retaining capacities. “During the southwest monsoon this year, due to heavy rainfall in the catchment areas, most of these rivers received heavy rain and consequently the inflows to these reservoirs were above normal. As a result, most reservoirs were filled to their maximum water storage capacity,” the report said.


The heavy outflows from these reservoirs was much more than the carrying capacities downstream and ended up flooding adjoining areas. Under a chapter dedicated to reasons behind the landslides in Kodagu that killed 16 people, the state government said: “The heavy rainfall and huge amount of water released from the reservoirs flowing in the downstream channels... some of them running parallel to the roads, scooped the area by causing landslides in the adjoining hills and severe damages to roads and buildings in the area.”

The government listed five other reasons which contributed to the disaster in Kodagu and Malnad – sensitive topography or slope failures (slopes along the highways posing risk of rainfall-induced slope failures), human-induced mass movement which subjects a slope to a load that exceeds its ability, heavy rains leading to slope saturation and decreasing the effective cohesion and generating hydrostatic pressures in the soil profile allowing significant slope failures and finally, inadequate retaining walls for roads, lack of drainage, clearing of vegetation and weakening of slopes through unscientific construction of houses.

Geology experts like TR Ananth Ramu believe the disaster was more “manmade” than natural.“The Kodagu disaster is a classic case of multi-organ failure, with multiple reasons for the devastation. But primarily, the timber mafia and unauthorised construction of tanks atop the hills by coffee planters appear to have been the catalyst for the landslides,” said Ramu.

“Very few people realise that Kodagu region and Western Ghats in Karnataka fall under seismic zone III. This does not mean it is very weak or very strong, but even the slightest of shakes along the seismic zone will add to the already heavy rainfall receiving parts of the region and cause landslides,” added the retired geologist from Geological Survey of India (GSI).