Urban flood analyses in sloping areas with 3Di modelling

Abstract

During extreme rainfall the limited storage and discharge capacity of sewer systems can result in temporary accumulation of water on street level. The purpose of this research is to evaluate the suitability of 3Di modelling for urban pluvial flood analyses in sloped areas. For this research purpose a case study is performed in the villages of Banholt and Mheer in the south of Limburg.

The analysis, conducted with a 3Di model, provides insight in the flood prone locations, and the magnitude and causes of flooding at these locations. Added value of 3Di can be found in the possibility to include both 1D sewer flow and 2D surface flow simultaneously. Inclusion of both systems, and their interaction, is of added value because most flood locations in the research area appeared to be flood prone due to a contribution of both systems.

Based on the lessons learned during this research, recommendations for future improvements of the 3Di model Banholt-Mheer and the 3Di modelling toolbox in general are given. Improvement of the 3Di model for Banholt and Mheer is related to calibration and validation of the model. To improve the performance of the 3Di modelling toolbox in sloped areas, future research should focus on the consequences of the subgrid technique in sloped areas compared to flat ones.