Hazard assessment of glacial lake outbursts in the Doyinongba Basin, southeastern Tibetan Plateau

Abstract

Glacial lake outburst disasters are the phenomena of outburst floods or debris flows induced by the sudden destruction of glacial lake dams. It has a serious impact on human activities and the natural environment. Recently, the glaciers in the southeastern Tibetan Plateau have retreated rapidly, and the number and scale of glacial lakes have increased significantly, causing frequent occurrences of glacial lake outburst in the southeastern Tibetan Plateau. Dynamic changes in glaciers and glacial lakes, process simulation of the glacial lake outbursts triggered by ice avalanches, and the movement process of glacial lake outburst debris flows were investigated by combining multitemporal Landsat series satellite images, Sentinel-2A satellite images from 1995 to 2021, and the rapid mass movement simulation hydrodynamic modeling(RAMMS). Hazard zoning of debris flow areas was estimated according to the flow velocity and flow depth in the debris flow simulation. The results indicate that the glacial area in the basin shrinks from 14.05 km2 in 1995 to 9.43 km2 in 2021, and the average annual rate of shrinkage is 0.15 km2/a. There are three ice avalanches in the basin, all of which may trigger the collapse of the glacial lake. When the potentially dangerous glacial lake is drained completely, the debris flow rushing out of the ditch may block the mouth of Ranwu Lake and the main river channel of Palongzangbo, posing a threat to the residents and roads downstream. The impact area is approximately 4.05 km2, and the high-risk area is approximately 2.55 km2. The above-mentioned results provide a basis for land use planning, disaster prevention, and mitigation inthe Doyinongba basin, guiding the hazard assessments of glacial lake outburst debris flows in the southeastern Tibetan Plateau.

Keywords

• glacial lake outburst
• ramms
• hazard assessment
• ice avalanche
• southeastern tibetan plateau