This project offers a solution to determine potential risk areas for flooding for communal planning. It defines sinks and secondary flood streams where surface water accumulates after heavy rainfall. The method is based on a flow accumulation analysis in ArcGIS. The major challenge showed to be the construction of hydrological correct height models that were generated from laser data in combination with vector data. An evaluation revealed an overall satisfying accuracy. Major findings are recommendations for the construction of height models, the choice of tools and conclusions on a relevant size of sinks and flood streams.