From radar-based heavy rainfall event monitoring to impact assessment (an example from Germany)

Extreme rainfall events, due to its dynamic and still not always predictable character, continue to be a subject of social concern even in a highly-developed country such as Germany. They can lead to numerous hazards, like flash-floods, landslides and soil erosion, causing damages and huge economic costs, as well as direct risk to human life. 

Thus, not only the real-time monitoring but also a deep analysis of past extreme precipitation events has a crucial meaning in understanding their possible impact. The investigation of past losses and risk factors can help to estimate the potential danger and shape human sensitivity to weather extremes.

With this objective, the Deutscher Wetterdienst (DWD) performs a radar-based object-oriented identification and classification of extreme rainfall. For the past events that occurred over the area of Germany in 2001-2021, the Catalogue of Radar-based Heavy Rainfall Events (CatRaRE) is available. It is derived from high-resolution climatological data (1h, 1km - RADKLIM). For the current cases of heavy rainfall, quasi real-time monitoring based on hourly operational hourly RADOLAN data is performed.

For all detected events a wide range of indices and extremity attributes (e.g. return period, heavy precipitation and weather extremity indices) were determined. The geospatial character of the dataset has allowed also for an enrichment with e.g. socioeconomic and geophysical variables, building the substantial basis for a risk analysis. In addition, combining meteorological and non-meteorological characteristics of each event with available data on corresponding insurance losses, fire-brigades’ operations or crowdsourcing reports served for an impact quantification. Through those steps, we obtained a rich basis that can be also used operationally as a lookup table when estimating a possible impact of current or forecasted events that show similar characteristics.

We will present results of a heavy rainfall hazard mapping for the area of Germany together with an impact analysis of all classified heavy precipitation events. In addition, we will give examples for using the extended version of the CatRaRE Catalogue as a basis for assessing the impact of operationally detected and/or predicted precipitation events.