Improving TELEMAC on a Simple Test Case to Simulate Runoff and Erosion Generation

This paper focuses on how to ensure the robustness of the resolution of Shallow Water Equations in the TELEMAC2D computation code in the case of rain induced runoff on steep slopes. To reproduce these conditions, a straight channel with a variable slope on which drops a constant rain is defined. With this test case, a comparison between the simulated discharge at the outlet and an analytical solution of the Shallow Water Equations for the rising part of the hydrograph and the plateau has been done. By stopping the rain in the middle of a simulation, numerical results and an analytical solution of the kinematic wave approximation were confronted during the emptying of the domain. Limitations of the numerical resolution are highlighted with the finite volume schemes. Improvements were made to better represent the rainfall-runoff responses, like another method of hydrostatic reconstruction [7] which has been implemented. Then, the model is extended to pollutant transfers and sediment transport in suspension. These results provide a strong basis for future application of modeling erosion at the watershed scale.