Assessing Rainfall Risk and the Impact of Extreme Precipitation Events in Germany Based on a Catalogue of Radar-based Heavy Rainfall Events (CatRaRE)

One of the predicted effects of climate change in Central Europe is a growing number and increasing extremity of heavy rainfalls. Thus, it is of a great importance to investigate the structure and detailed characteristics of extreme events that have already taken place and understand the possible impact each event may provoke.

DWD’s Catalogue of Radar-based Heavy Rainfall Events (CatRaRE) provides a comprehensive list of all spatially and timely independent rainfall events with duration between 1 and 72 hours exceeding the official warning level for heavy precipitation for Germany based on climatological radar data (RADKLIM) between 2001 and 2022. Apart from various extremity attributes, like return period or weather extremity indices, the catalogue is enriched with additional variables (e.g. weather type, antecedent precipitation index, population density, land cover), providing the meteorological, geographical and demographic background for comprehensive studies of extreme precipitation events and their impacts.

According to the IPCC risk is defined by three main determinants: hazard, exposure and vulnerability. RADKLIM and CatRaRE provide information on the hazard. In order to determine the exposure for precipitation induced floods, imperviousness degree and topographic position index (TPI) are combined. Together with data on antecedent precipitation and soil moisture the current risk can be determined. Potential vulnerability is estimated on the basis of socioeconomic factors and past losses. Information on the impact of each event in CatRaRE (e.g. on damage or fire brigade operations) allows an estimation of the possible impact that current or upcoming events with comparable structure could provoke in a similar environment, i.e. with similar risk.

We will present CatRaRE and first results of the rainfall risk map as well as examples of how to use the risk map for assessing the impact of operationally detected or predicted precipitation events from nowcasting.