Prediction of Debris-Flow and Flood Characteristics Caused by Potential Outburst of the Imja Glacial Lake in Nepal

摘要

Debris flows and floods caused by outburst of glacial lakes have frequently occurred in the Himalaya of South Asia. The frequency of these disasters has been increasing tremendously due to global climate change. It is thus necessary to investigate debris-flow and flood characteristics due to outburst of glacial lakes in order to manage the hazards and risk in the areas. In this study, the characteristics of debris flows and floods caused by potential outburst flood from the Imja glacial lake in Nepal due to moraine dam failure by water overtopping were analyzed using developed numerical model. The numerical model was validated with the flume experimental cases. The relationship between peak outburst discharges with the volumes of lake water for experimental conditions was also analyzed. The erosion and deposition processes along the river valley were also considered in the analyses of potential outburst floods from the Imja glacial lake. Sensitivity analyses of the parameters of river bed sediment were also conducted. The predicted results of debris-flow and flood characteristics such as outburst discharge, flood arrival time, sediment concentrations, peak flow velocity and maximum flow depth can be useful for effective preventive measures, river basin management and infrastructure planning in the river basin.