Simulation of glacial lake outburst flood hazard in Hunza valley of upper Indus Basin

Abstract

The UIB (Upper Indus Basin) is prone to GLOFs (Glacial Lake Outburst Floods). Physical monitoring of such a large area on a regular basis is a challenging task, especially when the temporal and spatial extent of the hazard is highly variable. The purpose of this study was to map the potentially dangerous glacial lakes and simulate the associated hazard in the downward settlements using HEC-RAS in the GIS environment using Landsat 7 remote sensing data. The study was conducted in Hunza Valley of UIB, where there are several human settlements that are endangered due to the GLOF hazard. Sudden breaches in the unstable moraine dams adjoining receding glaciers may occur because of the rapid and huge accumulation of turbulent water in the glacial lakes. The ASTER GDEM (Digital Elevation Model) is utilized to detect flow accumulation of glacial hazard involving slope, elevation, and orientation of the mountain glaciers. The study results revealed that settlements of Hunza Valley are threatened by the GLOFs hazard. Keeping in view the seasonal growth of the potentially dangerous glacial lakes of Hunza Valley, a low discharge of 3500m3/s from a potentially dangerous glacial lake can affect 40%, whereas a moderate discharge of 5000m3/s can affect 60%, and a high discharge of 7000m3/s can affect 80% of the Shimshal village habitat. The results of the study can provide a platform for the establishment of an early warning and monitoring system to minimize the impact of future GLOFs. Accurate and comprehensive knowledge of potentially dangerous GLOFs is of utmost importance for risk management. A digital repository of GLOFs can enhance the ability to inform policymakers on the vulnerability, risk mitigation, and action/adaptation measures.