Tragedy in Sikkim

The catastrophe underlines big dam weaknesses

Global warming and big dams are literally proving to be a deadly combination, especially in the Himalayas, as the recent tragedy in Sikkim has demonstrated. With a death toll of 82 and rising, this disaster is the third of its kind in the past 10 years, involving heavy rain, glacial melt, and the failure of dams to control catastrophic flooding as a result. In 2013 and 2021, heavy rain precipitated glacial melting in the upper reaches of fast-flowing Himalayan rivers, sending enormous amounts of water tumbling downstream without warning, killing people and livestock and destroying properties worth thousands of crores in their wake in Uttarakhand. The disaster in Sikkim is no different, highlighting not just the failure of big dams but also poor coordination between disaster management systems in which satellite imagery that recorded a glacial lake outburst flood (Glof) could have been communicated downstream. The glacial lake burst its banks and flooded into the Teesta river, picking up debris along the way and ramming into the Teesta-III hydropower project, destroying a dam that directed water to this project and damaging large parts of the power project itself. In a matter of hours, the Teesta, which had been flowing below the danger mark, burst its banks, tumbling downstream to small towns and an army settlement.

The tragedy confirmed the worst fears of local activists who have been protesting against the plethora of hydro projects along the Teesta, which is said to be one of the most dammed rivers in India. According to NHPC, some 47 hydropower projects are under development along the Teesta in Sikkim and West Bengal. Of those, nine have been commissioned, 15 are being constructed, and 28 are in the planning stage. The Teesta-III project, built by the state government in public-private partnership mode, is the biggest run-of-the-river hydroelectric project in Sikkim. Big dams pose a greater threat to lives and livelihoods for several reasons. Rising temperatures are causing heavier and more unpredictable rainfall patterns and, therefore, the higher risk of incidents such as Glofs. The building of hydropower projects adds to the problem by disturbing the fragility of the Himalayan ecosystem, not least with the failure to follow safe engineering norms, and the indiscriminate dumping of construction debris along river beds, which blocks natural drainage channels, a problem that caused floods and landslides in Himachal Pradesh recently.

Down from the Himalayas and along India’s lowlands, too, big dams are becoming hazardous in also their inability to manage the impact of heavy rain. In 2019, in Karnataka and Maharashtra, for instance, floods were caused by the failure of dam administrators to calibrate water release in reservoirs to account for heavier rainfall. As a result, when reservoirs start to overflow, dam operators release far larger quantities of water, causing flooding instead of welcome irrigation for farmers downstream. As with the Himalayas and Glof formations, there is no coordination with the India Meteorological Department to anticipate heavy rain and calibrate water releases accordingly. Most dam operators focus on keeping reservoirs full rather than following international practices on regulating the filling and emptying of dams in accordance with rainfall patterns. All these tragedies point to an urgent need to review big dam management policies in the light of climate change.