The devastating Sikkim floods teach us several lessons

Planning for economic development in hilly regions should take climate impact into account and dams should never be built in ecologically sensitive areas

By Gurinder Kaur
Published: Tuesday 10 October 2023
Photo: Prem Singh Tamang-Golay, Sikkim Chief Minister M / Facebook

There has been devastation in Sikkim due to flash floods in the Teesta river after an outburst of Lhonak glacial lake in North Sikkim on October 4, 2023. As  of October 7, 18 people have died and 98 people, including 22 Army personnel, are still missing. Hundreds of houses, many roads and bridges have been washed away and two dams have been damaged.  

Sikkim is one of the 13 Himalayan states for which the central government has asked the Supreme Court to issue an order assessing their carrying capacity. It proposed the formation of an expert panel to evaluate the action plans submitted by each of them following the disasters in Himachal Pradesh and Uttarakhand in July and August. 

Read more: Sikkim floods: Why wasn’t early warning system set up at glacial lake known to be highly vulnerable? Experts ask

The massive flood in the Teesta was primarily the result of three events: Heavy rains due to cloudburst, the South Lhonak glacial lake giving way and the resulting flow of water breached the Chungthang dam, which serves the state’s largest hydropower project.

Despite efforts to repair or rebuild damaged infrastructure in order to recover from the disaster in Sikkim, it remains to be seen whether the state could have been spared. The Teesta river hydroelectric project, which was damaged on October 4, 2023, had many doubts even before it was commissioned in 2017. 

Way back in 2005, the Union Ministry of Environment, Forest and Climate Change’s steering committee for carrying capacity of Teesta Basin noted “sediment carried and deposited by glaciers, temporarily forming  glacial lakes and debris cones, is a potential source of hazard in North Sikkim.” 

The committee that approved the construction of the project in 2006 also warned that the project falls in an area of ​​glacial lakes, which is highly sensitive.

A 2020 report by the Sikkim State Disaster Management Authority also raised suspicions of an outburst at the Lhonak lake. There are 300 glacial lakes in the Sikkim Himalayan region, with 10 of them vulnerable to outbursts at any time and Lhonak lake was one of them, the report said. 

The lake was under government observation for many years. Apart from this, according to a report by the Forest and Environment Department of Sikkim, its area has increased significantly in the last five decades. The southern part of the lake has increased by 2.5 times since 1989.

 A 2013 report by the Indian Space Research Organisation found there was a 42 per cent chance of the Lhonak lake outbursting. An outburst of the lake is likely to release 19 million cubic metres of water downstream as the glacier above the lake is melting rapidly, it mentioned. 

Read more: Sikkim: Threat of South Lhonak lake bursting was forewarned by researchers two years ago

From 1962 to 2008, the glacier has shrunk by 1.9 to 2 metres and will shrink by another 11 metres over the next 11 years. A study published in journal Science Direct in 2021 warned of a catastrophe in Sikkim. Local activists in Sikkim have for long also been warning of the adverse environmental implications of the hydropower projects. 

The Teesta river flooding in Sikkim as a result of the lake outburst has caused the majority of the damage in the inhabited areas along the river banks. From 1985 to 2015, people living in river basins suffered more from floods, according to a study published in the journal Nature

Such a large tragedy could have been avoided if the Sikkim government had taken prompt action. About 31 per cent of Sikkim’s population lives in the river basins. The military camp washed away in the floods was also located on the floodplain.

Because of their varied shapes, large stones, gravel and sand brought by glaciers do not form a flat and solid surface. Despite repeated warnings from geologists and environmental experts, the state government paid no attention. Both the Teesta river dam and the city of Joshimath in Uttarakhand are built on glacier debris, putting the lives and property of the people in these areas at risk.

The planet is also warming rapidly, thanks to climate change — all the months from January to September in 2023 had above-average temperatures. The glaciers are melting faster and glacial lakes are filling up rapidly as well. This may further increase the possibility of lake bursting and flooding in the future.

The 2013 floods in Uttarakhand were caused by the melting of the Chorabari glacier and the breaching of the Chorabari lake. The February 2021 flood in Uttarakhand’s Chamoli was also caused by melting glaciers.

Read more: Sikkim, the land blessed by Guru Rinpoche, is being destroyed by anthropogenic activity: Yishey Doma

A 1.5 degree Celsius rise in average global temperature is also expected to melt half of the world’s glaciers by the end of this century. Mountainous regions of 12 countries in Asia, including India, Pakistan, China and Nepal, are at high risk due to melting glaciers.

Sikkim is situated in the Himalayan mountain range due to which landslides occur frequently. According to a report by the Geological Survey of India, 3,377 areas are in landslide zones where no construction should take place.

Several countries, including India, saw heavy rains in 2023 and dams broke, releasing water beyond their capacity, causing floods in the states and cities downstream of river basins. Punjab, Haryana, Uttar Pradesh, Bihar, West Bengal and other states saw heavy floods in July-August due to heavy rains in the hilly areas of India. 

At least 3,958 people lost their lives and significant amounts of property were destroyed in the Libyan city of Derna early in September 2023 as a result of the collapse of two dams. 

In 2004, India’s Central Electricity Authority planned to set up 162 projects for power generation, of which 10 were to be built in Sikkim. The number of these projects has only increased over time. Now, several hydropower projects are in various stages of development in Sikkim and West Bengal on the Teesta river, according to National Hydropower Development Corporation. Nine of these have already been commissioned, 15 are under construction and 28 more are in the planning stages. 

Teesta is one of the most dammed rivers in the country. More than half of the state’s hydropower projects are in the northern part of the state, which is now the most flood-affected region, found a study on hydel projects in the state by think tank World Water Council.

Larger dams with enormous storage capacities generate more hydroelectricity, but when it rains heavily and the amount of water in the dam exceeds its carrying capacity, the floodgates open, flooding the plains and wreaking havoc. 

Read more: Sikkim floods: Glacial lakes hold paleoenvironmental traces. What happens to them during outbursts?

The government should also take every precaution to repair dams on schedule. Lack of prompt dam maintenance in Libya has resulted in the deaths and displacement of thousands of people. There has been a terrible disaster in many Sikkim districts as a result of a portion of the Teesta river’s dam number 3 collapsing. 

Dams should not ever be built in hazardous or environmentally sensitive areas. Many factors have to be taken into consideration while constructing a dam. First of all, the opinion of geologists should be taken about the geological structure of the land and mountains in the area where the dam is to be constructed. 

Water carrying capacity of the area should also be taken into account. In addition, the dams should be small and have a low water storage capacity to prevent human casualties in the event of flooding. Large dams like Gujarat’s Sardar Sarovar Dam and Punjab’s Bhakra Dam should not have been built. 

Plans for economic development in hilly areas should be created and carried out with consideration for the earth’s rising temperature. Buildings, roads and homes should not be built near dams, water bodies (such as rivers, springs and lakes), landslide zones, or in hilly areas. Because hilly areas are more sensitive than plains, the state and federal governments should prioritise implementing various economic development schemes there. 

Gurinder Kaur is former professor, department of geography, Punjabi University, Patiala

Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth

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