Author(s): Sebastián Nash; Cristián Escauriaza; Antoine Rousseau

Linked Author(s):

Keywords: Urban flood; Porosity model; Sediment transport; Hyper-concentrated flows

Abstract: Floods are the most frequent disaster worldwide, causing significant damage, casualties, and economic losses every year. Urban areas, with their dense populations and infrastructure, face heightened flood risks due to accelerating urbanization and the increasing frequency and intensity of extreme climatic events. Urban flash floods are often characterized by high sediment loads, influencing flood dynamics and impacts. Numerical simulations are essential for assessing hazards and evaluating exposure during such events. However, conventional Shallow Water Equations (SWE) models require high computational costs due to their reliance on fine-scale topographic representation, making them impractical for real-time applications or probabilistic hazard assessments that require simulating multiple scenarios in a reasonable timeframe. Porosity Shallow Water Equations (PSWE) models address this limitation by offering significant computational speedups using coarse grids representing topographic features at a subgrid-scale. However, existing PSWE models typically assume clear-water conditions, neglecting the role of sediment concentration in shaping flood dynamics. This study explores the potential of coupling PSWE models with suspended sediment concentrations using a mixture rheological model. The objective is to determine whether the water-sediment mixture dynamics can be accurately represented in such a subgrid model framework and to identify the optimal spatial resolution that balances computational efficiency and accuracy.

DOI:

Year: 2025