A two-dimensional mathematical model for unsteady free-surface flows is presented,which facilitates a quantitative approach to the analysis of glacier-lake outburst floods.The governing equations of the model comprise the shallow water hydrodynamics equations closed with the Manning formulation for the boundary resistance.The second-order Total-Variation-Diminishing version of the Weighted-Average-Flux method,along with the HLL approximate Reimann Solver,is used to solve the governing equations,which can properly capture shock waves and deal with irregular boundaries.Numerical tests of dam-break flows are carried out to demonstrate the accuracy of the model under an idealized case with known analytical solution,and the ability of the model to properly reflect flow patterns under the case of irregular topography.The mathematical model is applied to predict the potential flood event due to sudden outburst of a glacial-lake under a practical situation,with given DEM of the basin and initial water level in the lake.The propagation of the glacial-lake outburst flood is assessed from a quantitative perspective.The mean flood flow velocity can be as high as 15 m·s-1,and the local bed shear stress can be as high as 1 000 N·m-2.The highly energetic flood flow should trigger very active sediment erosion,transport and deposition,and debris flow hazards may be inevitable in the particular situation.This finding appears to characterize the need for the extension of the present mathematical model for purely unsteady flows to a coupled model for flow,sediment transport and morphological evolution.
- 岳志远, 曹志先, 车涛, 李新. 冰湖溃决洪水的二维水动力学数值模拟[J]. 冰川冻土, 2007, 29(5): 756-763.
- YUE Zhi-yuan, CAO Zhi-xian, CHE Tao, LI Xin. Two-dimensional Mathematical Modeling of Glacier Lake Outburst Flood[J]. JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY, 2007, 29(5): 756-763.