Risk Assessment of Glacial Lakes in the Himalayas

Abstract

With global climate warming, glaciers in the high-altitude regions of the southern slopes of the Himalayas are melting at an accelerated rate, resulting in the formation of numerous moraine-dammed lakes. Some of these lakes are at risk of catastrophic flooding due to the
instability of their dam structures, potentially triggering Glacial Lake Outburst Floods (GLOF) that threaten the lives of downstream residents,
infrastructure, and the ecological environment. This study focuses on a typical glacier lake (coordinates: 27.9500 N, 88.3290 E) on the southern slope of the Himalayas, combining remote sensing technology with hydrological modeling (HEC-RAS) to simulate the outburst flood
process and assess the flood risk to key downstream hydropower stations. The results indicate that under average conditions, when the breach
width is 100 meters and the breach time is 45 minutes, the peak flood discharge downstream of the lake reaches 1850 m/s. After 72 km of
river channel evolution, and considering a 100-year return period flood (1500 m/s), the peak discharge at the downstream hydropower station
reaches 2, 950 m/s, with a propagation time of 2 hours and 15 minutes. This research provides scientific support for regional flood control
planning and hydropower safety design.