DAMNED BY OUR DAMS AS SAFETY ISSUES SWIRL

The country has over 6,000 large dams. And a staggeringly large number of them are ageing

- Sindhu Bhattacharya

It was the intervening night of 3 and 4 October. Most residents of Chungthang were deep in sleep when a surge of water in the Teesta river triggered flash floods that laid waste to the settlement in north Sikkim—home to around 4,000 people.

When officials took count of the devastation, as many as 42 people had been killed in the Teesta basin, and 77 missing and presumed dead. Thousands had been displaced. Those who escaped did so with just the clothes they were wearing; they had no time to salvage anything else.

The hydropower dam over the Teesta was destroyed and the associated 1,200MW Teesta-III hydropower project submerged by the swirling waters in the disaster that rekindled an old debate: how safe are India’s dams?

Experts blamed what they call a Glacial Lake Outburst Flood, or GLOF, in the South Lhonak lake, for the disaster.

Glacial lakes sit atop or below a melting glacier and as they grow larger, they become more perilous. They are blocked by ice or sediment of rock and debris, and if the boundary breaks, waters surge down the mountains, flooding downstream areas. This phenomenon is known as GLOF.

It’s not as if the authorities had been caught totally unawares. As far back as 2015, glaciologist Anil Kulkarni had warned the Sikkim government about the formation of a lake in the South Lhonak glacier, which had been melting rapidly, and suggested that an early warning system be put in place to avert a disaster.

Kulkarni, a scientist at the Divecha Centre for Climate Change in Bengaluru-based Indian Institute of Science, was co-author of a paper that highlighted high risk posed to many settlements along Chungthang valley because of the construction of a hydropower dam over the Teesta river.