Geospatial Analysis and Modeling of Glacier Avalanche and Glacial Lake Outburst Flood Hazards in Shigar and Shyok Basins of Pakistan

Abstract

The upper Indus Basin (UIB) glaciers are melting / retreating due to global warming. This has created potential hazards of glacier lake outburst flood (GLOF) and glacial avalanche to the downstream settlements. The objectives of this research study was to (i) simulate and model Gyari glacial avalanche with reference to its extent, height, momentum, velocity and pressure, (ii) simulate and model the other potential glacial avalanche prone areas using Rapid Access Mass Movement Simulation (RAMMS), (iii) map the potentially dangerous glacial lakes in study area, and simulate the associated hazard to the downstream settlements using Hydrological Engineering Center–River Analysis System (HEC-RAS). To achieve the first objective RAMMS model was validated with the data of Gyari glacier avalanche and the selected glaciers in Shyok and Shigar basins posing threat to downstream settlements were simulated. The RAMMS model simulation output of Shyok glacier generated a max pressure of 2500 KPa, velocity of 75 m s-1, flow height of 60 m, and a momentum of 2800 m2 s-1. This simulation resulted damage extent of 700 m in the downstream Shyok settlement. In case of Shigar glacier RAMMS simulation resulted a max pressure of 2000 KPa, velocity of 75 m s-1, flow height of 70 m, and a momentum of 4000 m2 s-1. This simulation resulted damage extent of 500 m in the downstream Shigar settlement. To achieve the second objective HEC-RAS model was used to simulate the GLOF hazard to downstream settlement in the Shyok basin. The HEC-RAS model simulation resulted that in worst case scenario of both glacial lakes outburst, a low discharge of 100 m3 s-1 can affect 20%, a moderate discharge of 300 m3 s-1 can affect 30% and a high discharge of 500 m3 s-1 can affect 40% of the Barah 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 avalanche and GLOF events. The research study has resulted in identifying the Siachen glacier conflict zone being more prone to avalanche and GLOF hazards because of global warming in general and the anthropogenic factor in particular.