GRSG Conference 2022: Orbit to Outcrop
Title: Spatio-temporal Appraisal of Glacial Lakes, Susceptibility Analysis and Potentials of Glacial Lake Outburst Floods in the Peri-Glacial Environment of Western Himalayas
Author: Prof. Dr. Atta ur Rahman
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 remains 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 have been increased from 120 in 1989 to 128 in 2019, whereas the areal extent of the glacial lakes have 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.