Generation of type-specific synthetic design flood hydrographs

Design flood hydrographs are essential for hydraulic engineering and flood risk assessment. Typically, they are derived from quantiles estimated from flood frequency analyses of flood peaks. This usually does not take into account that one and the same flood peak can occur with different volumes and various hydrograph shapes due to different meteorological and catchment-specific processes. In view of this issue, we generate design flood scenarios, i.e. type-specific design hydrographs are created for a flood quantile of a certain return period based on type-specific flood volumes and hydrograph shapes. Additionally, the probability of each flood type is derived. Different probability density functions are used as templates for generating different hydrograph shapes by varying their parameters. An ensemble of synthetic design flood hydrographs is obtained, which allows the consideration of best- and worst-case scenarios. A case study for 162 catchments in Germany demonstrates the applicability of the approach.