A Swollen Lake Swallowed Sikkim: Flash Flood Predicted in 2021

The flash flood, triggered by a cloudburst in the early hours of Wednesday, had a significant impact on over 25,000 people in the scenic Himalayan state. It caused extensive damage, including over 1,200 houses destroyed and the loss of 13 bridges.

The question arises: what led to this catastrophe? The answer lies in the influence of climate change, which has played a pivotal role in exacerbating the severity of this weather event. Just understand in simple words- the length of Lhonak glacial lake is continuously increasing because of the speedy melting process on the top of the peaks. Scientists alerted the administration about the flash flood in 2021. The study in 2021 highlighted the growing size of the Lhonak glacial lake, which was particularly sensitive to extreme weather events such as cloudbursts.

But, nobody bothered about it and finally, the flash flood affected 25,065 people across four districts - Mangan, Gangtok, Pakyong, and Namchi.

Current Situation in Sikkim

Currently, road connectivity between these districts has been severed, and numerous bridges have been washed away, severely impacting communication in North Sikkim. The toll in the flash flood in Sikkim rose to 27 on Saturday even as search operations continued for the 141 people who are still missing.

However, what we urgently need to emphasize is the profound impact of climate change. We must connect the dots to understand the cause of this cloudburst.

Robust Disaster Management Plan is a need of an hour

According to climate scientists and meteorologists, the only viable solution to safeguard the people of the Himalayas from such incidents is meticulous disaster planning and mitigation, as the exact timing of glacier-related floods or lake outbursts remains unpredictable.

South Lhonak Glacier's melting over the years is a matter of great concern. Multiple studies have shown that it is one of the fastest-retreating glaciers, resulting in the expansion of the connected lake, which is now the largest and fastest-growing in the state.

The glacier retreated approximately 2 kilometers from 1962 to 2008 and then receded another 400 meters from 2008 to 2019. This has raised alarm bells due to the downstream valley's high population density and existing infrastructure.

According to scientists, these types of floods can be triggered under extreme meteorological conditions, especially heavy rainfall events that erode the damming moraine and lead to the lake overflowing.

Increasing Silt

Another factor contributing to the problem is the increasing silt deposited by the retreating glaciers. Glaciers contain a mixture of loose sediments, and in the higher Himalayan regions, this sediment concentration is so high that even minimal rainfall can transport boulders and debris downstream, making it unsuitable for dams and tunnels.

Sensitive Seismic zone

Furthermore, seismic activity in the highly active seismic zone where South Lhonak Lake is situated can compromise the structural integrity of the moraines, potentially leading to catastrophic ice/rock avalanches. If you talk about the whole Himalayan Region, from Hindukush to Myanmar the whole region is sensitive about earthquakes.

Erratic Monsoon Patterns

The erratic monsoon patterns in the Eastern Himalayas, dominated by monsoons, have exacerbated the situation. Snowfall, which nourishes glaciers, has been replaced by erratic rainfall patterns, with more heavy rain days and increasing dry periods due to global warming leading to increased glacial melt.

What do scientists say about the Sikkim Flood?

The views of scientists on the Sikkim cloudburst incident shed light on the issue. Dr. Farooq Azam, a glaciologist from the Indian Institute of Technology-Indore, noted that the breach of this lake and its impact on the dam had already been predicted in 2021. He explained that as glaciers advance, they erode the riverbed, deepening the river, and climate change has resulted in erratic precipitation patterns, including cloudbursts, which can partially breach moraine dams.

Prof. Mahendra P Lama, Founding Vice Chancellor of Sikkim University, expressed sadness at the devastation and highlighted the warnings about potential floods and glacial lake outburst floods in earlier reports. He emphasized the potential of harnessing renewable energy from mountain rivers for regional development but stressed the need for responsible project implementation and environmental impact assessments to avoid disasters.

Anjal Prakash, a Clinical Associate Professor and Research Director at the Bharti Institute of Public Policy, Indian School of Business, and an IPCC Author, emphasized the lack of monitoring of the vast number of glaciers across the Hindu Kush Himalayan region. He suggested that scientific monitoring and data sharing with policymakers are essential to make informed decisions and prevent such disasters from escalating further.