Downstream communities fear glacial lake outburst

Rajan Pokhrel

Kathmandu–The April earthquake and its aftershocks have destabilised the already deteriorating terminal or lateral moraines of Imja, Tsho Rolpa and Thulagi lakes, according to a scientific study, which also suggested the authorities to reclassify them under the ‘dangerous’ category.

After concluding a month-long field study, Alton C Byers, lead scientist from the University of Colorado, US, told this daily that the earthquake and aftershocks caused an increase in the destabilisation of three glacial lakes – Imja in the Mt Everest region, Tsho Rolpa in Rowaling and Thulagi in Manaslu region, leaving the communities downstream highly fearful of the likelihood of glacial lake outburst floods (GLOFs) occurring in the near future.

According to him, the April temblor created massive cracks and shifted boulders impacting on the outlet channel to further destabilise existing potential GLOFs. “Our study suggests that all three lakes should be re-classified as being dangerous, not ‘potentially dangerous’,” he said referring to the findings of the study.

The destabilisation could have resulted in overhanging ice, calving rates of the glacier termini, deterioration of the terminal moraine, and mass wasting of the lateral moraines, the study adds.

It is likely that the number, frequency, and magnitude of GLOFs will be increasing in the aftermath of earthquake but the downstream communities lack adequate information about existing or planned early warning systems, lake risk reduction methods and disaster management planning, the study, which was conducted through detailed remote sensing and field-based assessments, highlighted.

The researcher also observed that nearly every boulder in Tsho Rolpa’s terminal moraine had shifted, while Imja Lake had produced abundant new cracks parallel to the lake shore.

Comparatively, Thulagi Lake was safe, adds the report.

“We should not wait until GLOFs kill people and destroy hydropower installations before taking action,” Prof Byers said, adding that the team also felt that detailed scientific surveys of all lakes should be conducted without wasting time, Himalayan-specific methods should be designed to reduce risks and funds should be mobilised to accomplish all tasks.

Volunteer scientists — Daene C McKinney from University of Texas and Elizabeth A Byers of West Virginia Department of Environment Protection — and Ram Kumar Kapair of DHM were commissioned by the High Mountains Adaptation Partnership to conduct post-earthquake assessment of three lakes.

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