Spatio-temporal appraisal of glacial lakes, susceptibility analysis and potentials of glacial lake outburst floods in the peri-glacial environment of Western Himalayas

Abstract

This study is focused on Spatio-temporal monitoring of glacial lakes, susceptibility analysis
and potentials of glacial lake outburst floods (GLOF) in the Periglacial environment of western
Himalayas. In the study region, parallel to recurrence of GLOF events, the number and volume
of glacial lakes in the peri-glacial area are increasing. In western Himalayas, 52 out of 2,600
glacial lakes are considered as potentially dangerous. Astor Drainage Basin (on which the
present study is based), host numerous glaciers and glacial lakes whereas, Glacial Lake
Outburst Floods (GLOFs) are recurrently occurring phenomenon. It has a geographical area of
about 3988.7 km² and the altitude varies from 1237m to 8105m amsl. The study area receives
heavy precipitation and most of the peaks remain under snow year-round. The data were
collected from Astore, Rama, and Rattu met stations, while discharge data were obtained from
Doyian station. It has been calculated that there are a total of 372 small and large glaciers
spread over an area of 239.59 Km² making 6% of the total area. The analysis revealed that the
number of glacial lakes has been increased from 120 in 1989 to 128 in 2019, whereas the areal
extent of the glacial lakes has been increased from 4.75 km² to 5.861 km², respectively. During
the study period, out of total glacial lakes, 2 (two) were vanished whereas, 10 new lakes were
formed. Furthermore, for carrying out susceptibility analysis, twelve GLOFs factors including
slope, lake area expansion, aspect, lake type, distance between glacier’s snout and lake,
precipitation, elevation, distance to settlement, land surface temperature, distance to road
network, fault lines and surface lithology were prepared and weight were assigned using
Saaty’s Scale. Subsequently, the final GLOF susceptibility zonation map was developed and the
results were classified into free zone (20.340%: 796.4622 km²), very low susceptible area
(32.272%: 1263.6660 km²), low (25.644%: 1004.1560 km²), moderate (13.610%: 532.9245
km²), high (6.154%: 241.0049 km²) and very high susceptible zone (1.9%: 77.4288 km²) of
the total geographical area of Astore Drainage Basin, respectively. In the study area, the GLOF
event frequently hit the downstream communities and poses serious threat to vulnerable
communities. It is therefore, monitoring glacial lakes and GLOF susceptibility zonation may
assist DRR managers and policy makers in taking appropriate measures for the reduction of
GLOFs related damages