Author(s): Jean-Paul Travert; Florent Taccone; Vito Bacchi
Linked Author(s): Vito Bacchi
Keywords: No Keywords
Abstract: Introduction Extreme floods have become more frequent and severe in the recent years exacerbated by climate change. There are numerous recent examples of major floods such as the July 2021 catastrophic flooding events in Germany, Belgium and in China, or the April 2022 floods in South Africa. These extreme events caused human casualties, high economical costs and damages in sensitive areas. To design appropriate mitigation measures, especially with increasing urbanization and decreasing infiltration rates, numerical models are proactive tools widely used. This study investigates the September 8th and 9th France flooding event in France. During this extreme event, historical records of more than 130 mm of rainfall in two hours were locally measured at Agen, causing exceptional runoff. The main objective of this study is to propose an approach to test the ability of the TELEMAC-2D depth-averaged computation code, (www. opentelemac. org) to simulate runoff on a large catchment with a good accuracy both for discharges and water depths and evaluate the computation cost, necessary for practical applications. A physically based model allows using water depths and spatialized velocities data in the catchment with a better accuracy than the widely spread conceptual rainfall-discharge models. Some rainfall-discharge models using the Shallow Water Equations (SWE) in 2D, using finite volume schemes with hydrostatic reconstruction (Chen et al., 2017) have already been used successfully for extreme events on rather small catchments up to 100 km2 (Taccone et al., 2020; Brigode et al., 2021; Yassine et al., 2021), but there is still a need to test and extend the methodology for larger catchment cases. In this study a global methodology is proposed to model runoff on a large catchment. It will be described the process of cutting the catchment in sub-catchments for implementing a physically based model of this scale.
Year: 2022