The successful draining of Imja Lake, one of the fastest-growing and potentially threatened glacial lakes in Nepal, has highlighted the achievement of local expertise to mitigate glacial lake outburst floods risk caused by climate change, threatening the mountain communities, according to experts. 

A team representing the Engineering Department of the Nepal Army has successfully completed draining Imja glacial to a safer limit by 3.4 meters. The NA team started building a 46-metre drainage channel in September and drained 5 million cubic metres of water from the lake by the October-end this year, said Top Khatri, project manager of the Community Based Flood and Glacial Lake Outburst Risk Reduction Project under the Department of Hydrology and Meteorology.

“The successful completion of the draining the lake from the potential threatening level to a safer limit with the help of local expertise is a big achievement to us. This will help in mitigating hazard risks of other potential threatened glacial lakes in the country,” he said. The project, being implemented by the DHM with technical assistance from the Nepal Army, is funded by the United Nations Development Programme and the Global Environment Facility. 

Located at around 5,100 metres above sea-level in Khumbu region in Solukhmbu district, Imja Lake is believed to be 149.8 metres deep with 75 million cubic metre water. The $7.2 million project aimed to prevent the loss of human lives and physical infrastructure from a glacial lake outburst flooding in Solukhumbu and the downstream Tarai and Churia districts of Mahottari, Siraha, Saptari and Udaypur. An estimated 96,562 people living downstream are expected to directly benefit from the project.

Besides the construction of the drainage canal, according to Khatri, the project has also helped in installation of Community-based Flood Early Warning System to help the communities living at a distance of 50 km downstream from the lake site get early warnings in the event of any potential disaster in the future. There are 12 critical settlements located along the 50-km stretch downstream from the lake. The National Adaptation Programme of Action has identified six glacial lakes, including Imja, as the highly vulnerable glacial lakes posing threats of potential flooding disaster to the downstream communities. 

In 2000 in Dolakha district, Tsho Rolpa, another critical glacial lake that threatened to burst anytime by breaking its unstable moraine dam, was reduced by three metres with the help of a 70-metre canal that channelled water into the Rolwaling river.