Parameter Uncertainties in Flood Hazard Analysis of Heavy Rain Events

Abstract

Flooding due to intensive precipitation poses a major threat to lives and property. To deal with the resulting risks, information about flood-prone areas regarding water levels and flow velocities is needed. The flood probability of a certain point in the landscape depends on the one hand on the occurrence probability of a surface runoff generating–rainfall event and on the other hand on the flow- and runoff-determining properties of the terrain, e.g., the surface morphology and the hydraulic roughness. Simulation models for the flow of surface water are common tools for assessing the dynamics of flooding caused by intensive precipitation events. Major input parameters for such simulation tools are digital elevation models, surface roughness datasets, as well as data on the precipitation input. In order to make informed decisions that take the uncertainties of modeling results into account and to get an idea of the probability space, it is important to quantify the effects of different alternative model parameter sets regarding data sources as well as the spatial and temporal resolution of the input data. We evaluated the effects of different parameter sets for the hydronumeric computational fluid dynamics model HiPIMS on flow velocities and water levels.