Determination of Pluvial Flood Hazards for Critical Infrastructures and Buildings Taking in Account Impacts of Grid Resolution in Grid-Based Flood Models

Abstract

The identification of flood hazards and flood risks (spatial overlay of flood hazards and potential damage) are basic tasks of flood risk management. Due to a lack of data for a comprehensive assessment of potential damage in urban areas, flood risks are often only determined for buildings (based on the building use from real estate cadastres). Therefore, building-related statements about flood hazards are required to assess flood risks. In practice, flood hazards for buildings are usually determined from results of hydrodynamic 2D surface runoff models using simple methods. These methods do not take into account the fact that building structures in the model may differ from the data of the underlying cadastre. This is particularly relevant for grid-based models, where the structure of a building in the model depends on the resolution of the calculation grid. To avoid inaccuracies inherent to these methods, we introduce a new algorithm. It first evaluates the results of a grid-based model on the basis of the calculation grid and then links them to the underlying building structures from the cadastre. Thus, differences between the rasterized buildings and their structure in the cadastre are taken into account. In addition we investigate the dependence of the results of the algorithm on the resolution of the calculation grid.