NEW DELHI: Following the recent catastrophic glacial lake outburst flood (GLOF) on October 3, 2023, which devastated sections along Sikkim's Teesta River, experts are raising alarms over the growing risks posed by hydropower projects situated near unstable glacier lakes. A new study, published by researchers from nine different countries, reiterates the vulnerabilities of such projects to climate change, stating these facilities might face unprecedented dangers from future GLOF events.
The study leads with the chilling details of the disaster caused when approximately 14.7 million cubic meters of frozen moraine collapsed, producing tsunami-like waves rising up to 20 meters high, and releasing about 50 million cubic meters of water. This flood obliterated infrastructure along its path, swallowing whole communities and tragically claiming the lives of at least 55 individuals, with 70 more reported missing.
“The South Lhonak outburst once again demonstrates the vulnerability of Himalayan hydropower to extreme natural events,” noted Wolfgang Schwanghart from the University of Potsdam. This sentiment resonates strongly considering just days after the flood, India's environment ministry’s expert panel provisionally approved the resumption of the construction on the halted 1,200 megawatt Teesta III hydropower project. While the project will be allowed to continue, government officials are urging caution and have mandated the installation of early warning systems to monitor changing environmental conditions.
Research conducted by the team led by Ashim Sattar of IIT Bhubaneswar utilized high-resolution satellite imagery and advanced modeling techniques to pinpoint the factors leading to the October disaster. By reconstructing the precise conditions at South Lhonak Lake, the researchers found the surrounding terrain had been increasingly unstable long before the GLOF. “The modified slope geometry…has increased the likelihood of future failures,” disclosed the study. The precarious nature of the area's geology makes it susceptible to future incidents, highlighting the urgent requirement for improved monitoring and preventive measures.
Previous assessments of geological stability revealed alarming shifts of up to 15 meters per year within the moraine structures. Consequently, it's predicted GLOFs will triple across the Himalayan region by the close of the century. Ashim Sattar pointed out the imperative to enact “a multi-faceted approach, including early warning systems, stronger regulatory frameworks, and community education” to minimize risks.
Alongside the immediate environmental concerns, the study also emphasized the influence of low-pressure systems contributing to significant rainfall across the Teesta valley, magnifying the impacts of the resultant flooding. Researchers argue the energy policies of Himalayan states must shift to address the perils posed by climate change proactively, factoring potential GLOF hazards significantly more than present efforts.
Sliding back to the aftermath of the GLOF, the Teesta III project—initially commissioned in February 2017—was operational until the disaster brought its functions to a screeching halt. The authorities are eyeing swift reinstatement, with restoration efforts estimated to possibly restore operations within 10 to 12 months. One suggested amendment to the project involves redesigning the dam from its original structure to one dubbed more resilient—a concrete gravity dam intended to mitigate risks of failure through overtopping.
Notably, apart from the Teesta III project, five other hydropower plants also fell victim to the overwhelming deluge, with damage extending well beyond the scope of energy infrastructure. Farms and local businesses found themselves inundated and eroded, exacerbated by the extreme weather conditions and rising global temperatures affecting the region.
The United Nations and other global organizations have echoed sentiments of the study, pushing the message for international cooperation and tool integration to combat such disasters effectively moving forward. “We need to establish frameworks and systems capable of offering real-time data on environmental parameters such as water levels and seismic activity,” explained Kristen L Cook from the University Grenoble Alpes, emphasizing the importance of shared knowledge across borders.
Conclusively, the combination of recent disaster insights and the prevalent risks underlying climate change present significant challenges for local communities and policymakers. Collaborative efforts are strictly warranted to construct adaptive and resilient systems capable not only of responding to threats but also preventing future catastrophic occurrences.