47 glacial lakes pose glacial outburst threat across Nepal’s major river corridors

Kathmandu, Aug 27 (IANS) Scientific assessments by the International Centre for Integrated Mountain Development (ICIMOD) and the Government of Nepal have classified 47 glacial lakes as Potentially Dangerous Glacial Lakes (PDGLs), warning that they could trigger catastrophic glacial lake outburst floods (GLOFs) into Nepal’s river systems.

Of these, 21 lakes are located in Nepal, while 25 are transboundary lakes in Tibet. These lakes are situated directly at the headwaters of rivers that flow southwards into Nepal, creating a potential threat to downstream communities and infrastructure.

Within this wider inventory, disaster management authorities and the United Nations Development Programme (UNDP) have identified a critical group of rapidly expanding, moraine-dammed lakes for urgent risk-reduction and lake-lowering interventions.

The most notable among them are Lower Barun (Tallopokhari), Thulagi (Dona), Lumding Tsho, Hongu 2 / Chamlang South, Tsho Rolpa and Imja Tsho.

The threat posed by these high-risk lakes is concentrated across several high-mountain and mid-hill districts located directly along downstream river corridors, putting communities and critical infrastructure in these areas at risk in the event of a major GLOF.

In Eastern and Central Nepal, covering the Koshi and Bagmati basins, more than 85 per cent of the total regional risk is concentrated in vulnerable areas.

The most exposed districts include Solukhumbu, covering the Dudh Koshi and Imja basins; Sankhuwasabha, along the Barun and Arun river corridors; Dolakha, along the Tama Koshi corridor and threatened by Tsho Rolpa; and Sindhupalchok, along the Bhote Koshi and Sun Koshi corridors, which is exposed to potential outbursts from transboundary lakes in Tibet.

Downstream river settlements in Ramechhap, Kavrepalanchok and Rasuwa, particularly along the Trishuli basin, are also vulnerable.

In Western and Far-Western Nepal, across the Gandaki and Karnali basins, direct impact corridors threaten communities and hydropower assets in several districts.

These include Manang and Lamjung along the Marsyangdi basin below Thulagi Lake, Gorkha along the Budhi Gandaki basin, Mustang and Myagdi along the Kali Gandaki basin, as well as the remote valleys of Humla, including the Limi Valley and the Humla Karnali corridor.

–IANS

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