Recession of glaciers throughout the Himalayas is resulting in the development of a growing number of high-altitude proglacial lakes that are retained behind natural moraine dams. Some of these have failed catastrophically and the consequential Glacier Lake Outburst Floods (GLOFs) have resulted in substantial damage and loss of life downstream. With growing populations in remote valleys coupled with the demand for substantial growth in the capacity for hydro-electric power for export, the risk of further disasters is increasing. Accordingly, His Majesty's Government of Nepal has undertaken a series of studies since 1985 to investigate the risks associated with such glacial lakes. This photofeature encapsulates aspects of the work undertaken between 1994 and 1997 at Tsho Rolpa, which is thought generally to be the largest and most dangerous glacial lake in Nepal. The present project at Tsho Rolpa is the first of its kind in Nepal and represents the first time that such detailed glacial hazard assessment has been undertaken through to the development of a full remediation scheme in Nepal.
Tsho Rolpa lies about 110 km north east of Kathmandu at the eastern end of the Rolwaling Valley (Fig. 1) and immediately south of Gauri Sankar (7146 m). The lake (Fig. 2) is about 3.5 km long by 0.5 km wide and is up to 135 m deep. It is fed by Trakarding Glacier (Fig. 3) to the southeast which is itself a composite glacier supplied by several glaciers from among the peaks to the east and south east of