Kottayam, KERALA — As the rains lashed down without respite, Devaki from Champakulam, who lives by the backwaters in Alappuzha, awoke one night to find that the water had risen as high as her bed.
"They said something about opening the Kakki dam and the Idukki dam," she said, recalling how she swam out of her house to the seek refuge on the closest boat. "But why did they open them all? It felt like the whole river came in."
The Kerala government's decision to open the sluice gates of 33 dams in the midst of an unprecedented flood has attracted much debate. Critics have argued that the unplanned release of million of litres of water from dam reservoirs exacerbated the flood, which has claimed at least 350 lives and washed away homes and infrastructure that took decades to build.
Kerala State Electricity Board (KSEB) engineers insist that they did all they could in the context of a 1-in-1,000 year inundation, in which the state received 42% more rainfall than normal, with districts such as Idukki receiving 92% more rain as compared with long-term averages over the same period.
Lost in this debate is the fact that the fundamental assumptions for safe operation of India's dams are no longer valid. Climate change means a 1-in-1,000 year inundation may occur more frequently than previously assumed; deforestation of upstream and downstream areas have reduced the carrying capacity of rivers — making it more likely that rivers will overflow their banks; while urbanisation has meant floods now have more devastating effects.
India has 4,877 completed large dams, the third largest number in the world after the United States and China, suggesting that it is crucial that policymakers, disaster management officials, and dam engineers learn from the devastation in Kerala.
A recent paper, presented at the Third National Dam Safety Conference in 2017, noted that most of these dams are over 20 years old, and "the original estimate of design floods was...