Author(s): Sazeda Begam, Dhrubajyoti Sen, Subhasish Dey
Linked Author(s): Sazeda Begam
Keywords: Moraine Dam failure, overtopping, glacial lake outburst flood (GLOF), TELEMAC-2D, SISYPHE
Abstract: The glacial lakes are increasing both in number and size and becoming more susceptible to causing Glacial Lake Outburst Flood (GLOF) due to global warming. The numerical simulation of moraine dam breach with better accuracy would help in understanding the extent of flash floods like GLOF more precisely. Moraine dam is a natural earthen dam formed by the material accumulated from a glacier which usually forms a glacial lake behind from the glacier melting water originating from its snout. This paper presents an approach for simulating the failure of a moraine dam by overtopping using a coupled numerical simulation model for flow and sediment movement (TELEMAC-2D and SISYPHE). The model simulates the breach formation of the dam and computes the resulting outflow hydrograph at the downstream of the dam. The embankment material is considered as non-cohesive and uniformly graded sand. The breaching process depends upon the shear stresses induced by the water flowing over the crest and downstream slope of the dam. After an initial breach is formed, the erosion of the dam proceeds spatially, which includes both vertical and lateral erosion. The study presents the simulation results from the 2D numerical model of the eroding embankment dam, which is compared with previously published experimental results. The numerical hydrodynamic model (TELEMAC-2D) is based on the shallow-water equations, which is coupled with the sediment erosion model (SISYPHE) in an interactive manner that takes into account the feedback between the water flow field hydraulics and the morphological changes of the dam surface profile. The governing law for sediment erosion code is that of Fredsoe and Rouse and is implemented by considering the material characteristics like critical erosion shear stress and erodibility factor. The results obtained from the numerical model are seen to match quite closely with the reported experimental results
Year: 2017