Towards fast large-scale flood simulations using 2D Shallow water modelling with depth-dependant porosity

Vita Ayoub (1, 2, 3) , Carole Delenne (3, 2) , Patrick Matgen (1, 3) , Pascal Finaud-Guyot (2) , Renaud Hostache (1)

1 LIST - Luxembourg Institute of Science and Technology
2 HSM - Hydrosciences Montpellier
3 LEMON - Littoral, Environment: MOdels and Numerics

In hydrodynamic modelling, the mesh resolution has a strong impact on run time and result accuracy. Coarser meshes allow faster simulations but often at the cost of accuracy. Conversely, finer meshes offer a better description of complex geometries but require much longer computational time, which makes their use at a large scale challenging. In this context, we aim to assess the potential of a two-dimensional shallow water model with depth-dependant porosity (SW2D-DDP) for flood simulations at a large scale. This modelling approach relies on nesting a sub-grid mesh containing high-resolution topographic and bathymetric data within each computational cell via a so-called depth-dependant storage porosity. It enables therefore faster simulations on rather coarse grids while preserving small-scale topography information. The July 2007 flood event in the Severn River basin (UK) is used as a test case, for which hydrometric measurements and spatial data are available for evaluation. A sensitivity analysis is carried out to investigate the porosity influence on the model performance in comparison with other classical parameters such as boundary conditions

Domaines: Environnement et Société

Vita Ayoub, Carole Delenne, Patrick Matgen, Pascal Finaud-Guyot, Renaud Hostache. Towards fast large-scale flood simulations using 2D Shallow water modelling with depth-dependant porosity. EGU General Assembly 2020, May 2020, Online /Vienna), Austria. ⟨10.5194/egusphere-egu2020-11562⟩. ⟨hal-03108327⟩