Mapping and monitoring of glacier lake outburst floods using geospatial modelling approach for Darkut valley, Pakistan

Abstract

AbstractClimate change and human activities have resulted in the receding of glaciers throughout the world including Pakistan. Glacier lake outburst floods (GLOFs) are amongst the most common climate‐change‐induced hazards in northern Pakistan. In the present study, GLOF mapping and modelling was carried out using remote sensing and geographical information system techniques coupled with ground‐truthing. Change detection techniques such as the normalized difference water index were applied on Landsat imagery for the identification of the temporal behaviour of Darkut glacial lake for the last 25 years. The depth of the lake was estimated to be 81 m and the volume of the lake was calculated using a digital terrain model and extracted as 9.79 × 106 m3. The glacial lake extent has increased from 0.045 to 0.154 km2 in the last two decades. Two GLOF scenarios (peak and extreme flood) were developed on an existing volume of water in the study. There are 14 households exposed to medium flood and 10 to low flood risk while one helipad and one school are also in the low flood zone in the first scenario (i.e. peak flood) based on 87.84 m3·s−1 of water. The second scenario (i.e. extreme flood) was executed on 3,128 m3·s−1 of water, in which 14 households are at high flood risk, eight at medium and 35 in a low flood zone, as well as one school, a helipad and a community stockpile which are exposed to low flood. The outcomes of the study will help in the development of risk management plans, preparedness strategies and risk reduction from GLOF hazard.