Author(s): Tim Jakobs; Peter Oberle; Mario J. Franca
Linked Author(s): Mário Franca
Keywords: No Keywords
Abstract: In the global risks report by WEF (2021), the risk of "extreme weather events" has been rated with the highest probability of occurrence for the fifth time in a row. In addition to fires, heat waves and windstorms, heavy rainfall and flash floods regularly appear and cause severe flooding with considerable damage to property and human life. To address the risk, heavy rain hazard maps based on 2D hydraulic models are created in Baden-Wurttemberg (Germany). In contrast to river hydraulics methods, the simulation of heavy rain surface runoff contains significantly greater uncertainties which ultimately affect the risk assessment and emergency response. The main challenges are defining geometrical boundaries, choosing appropriate spatial resolutions and the adequate quantification of the flow resistance. In addition, the impact of dynamic processes in terms of morphology and vegetation must also be considered. In previous studies, the determination of roughness parameters for thin layer surface flow was primarily based on field tests or laboratory experiments. In field tests with rain simulators, hydrological parameters (e. g. infiltration, erosion) have been investigated in general neglecting the detailed measurement of small-scale hydraulic processes (Engman, 1986). In laboratory experiments, precise measurements have taken place, but the model setup was mostly based on synthetic materials (e. g. artificial grass, asphalt), lacking relevant effects of heterogenous flow processes (Ruiz Rodriguez and Trost, 2017). In this context, it must be noted that small-scale geometric irregularities on natural surfaces and the effects on runoff concentrations as well as retention effects have a major influence on unsteady flow characteristics and have not been sufficiently researched to date (Kerlin et al., 2022).
Year: 2024