Surface water flooding
in Germany

Surface water flooding (sometimes called pluvial flooding or cloudburst) is causing increasingly intense localised flooding events in Germany on an almost yearly basis (Gesamtverband der Deutschen Versicherungswirtschaft, 2018). Across Europe, river and surface water flooding has increased almost twofold in the last 30 years, with surface water flooding events proportionally increasing at a higher rate (European Academics Science Advisory Council, 2018). As a result, it’s key for re/insurers in Germany, and across wider Europe, to understand the impacts this type of flooding can have on their business.

The impact of surface water flooding

Surface water flooding occurs when the amount of rainwater exceeds the infiltration ability of the ground or drainage systems. (See our blog River vs surface water flooding: what's the difference? for more information). These flood events cause a large volume of water to accumulate (pool) in a short amount of time. This pooling effect is very hard to forecast due to the dynamic nature of rainstorm events.

Re/insurers may wish to assess whether a property is located in a surface water flood risk area in order to make informed choices when underwriting. Surface water flood maps can support decision-making processes by indicating locations where pooling from this flood type may occur.

JBA first created a surface water flood map for Great Britain in 2008, followed by surface water maps for the rest of the UK. These maps are widely used in the UK re/insurance industry to support decision making and portfolio management. Until the release of JBA’s Germany Flood Map in 2019, a national-scale surface water flood map was not available in Germany, limiting re/insurers in making the most effective decisions in areas that may be impacted by surface water flood events, in addition to river flood risk.

Major heavy rainfall flood events in Germany

Since 1999, Germany has experienced numerous surface water flood events, resulting in billions of euros being paid out in insured losses. Reports suggest that the majority of flood damage in 2016, 2017 and 2018 was due to surface water (Gesamtverband der Deutschen Versicherungswirtschaft, 2018). These flood events are occurring on an almost yearly basis across Germany, but damage resulting from heavy rainfall is not automatically covered by German property insurance (Gesamtverband der Deutschen Versicherungswirtschaft, 2018).

During the summer of 2014, Storm depression Ela led to major surface water flooding in the city of Münster and around 24,000 households lost electricity [3]. The majority of flooding affected basements and roads, when around 40 million cubic metres of water entered the city, overwhelming the city's canals and watercourses (WeLT, 2015). This storm led to property insurers paying around €140 million for damages for the 30,000 claims experienced in Münster; the amount of damage caused across Europe meant Ela was the second most expensive summer storm between 2000 and 2015 (Die Deutschen Versicherer, 2015).

 

Figure 1: An extract from JBA’s new 5m Germany Flood Map, showing surface water flooding (purple) and river flooding (blue). The area illustrated is Kinderhaus, Münster, an area affected by extreme surface water flooding during Storm Ela in 2014.

Germany experienced further major surface water flooding in June and July 2017, when low pressure system Rasmund hit parts of northern Germany. In Berlin, 143.5 litres of rainfall were recorded falling in one square metre in just 24 hours: roughly one quarter of the yearly average or double June’s average for Berlin (Zeit Online, 2017). This event saw a total damage cost of around €60 million for the Berlin and Brandenburg regions, with an estimated €600 million has been paid out for the whole Rasmund low pressure system (Die Deutschen Versicherer, 2017). The event was described as a ‘once in a century flood’ and overwhelmed the drainage capacity of Berlin, leading to roads, cellars and even subways being flooded, bringing the city of Berlin virtually to a standstill (Berliner Zeitung, 2017; Berliner Morgenpost, 2017). Only 30% of residential properties in Berlin had insurance to cover this heavy rainfall event (compared to 40% nationally) (Berliner Morgenpost, 2017).

Figure 2: An extract from JBA’s new 5m Germany Flood Map, showing surface water flooding (purple) and river flooding (blue). The area illustrated is the Yorckstraβe U-Bahn (red marker) in Berlin. Berlin was affected by major surface water flooding caused by low pressure system Rasmund in summer 2017.

How can JBA help?

We now include surface water flooding as an additional flood type in all of our flood maps, including our new 5m Germany Flood Map and wider Europe 5m maps.

These maps help to identify the areas at risk of surface water flooding across a range of return periods to enable re/insurers and the property sector to make more informed decisions in risk selection, pricing, underwriting and portfolio management.

If you are interested in our flood maps for Germany, please get in touch for more information.

5m flood maps for Austria, Belgium, France, Germany, Italy, Luxembourg, Liechtenstein, Switzerland and the Czech Republic are now available at 5m resolution. Get in touch for more information.

References

Berliner Morgenpost. 2017. Berlin nach der Flut - die große Bilanz.
[online] Available at: https://www.morgenpost.de/berlin/article211090255/Berlin-nach-der-Flut-die-grosse-Bilanz.html [25 June 2019]

Berliner Zeitung. 2017. Jahrhundertregen Tief „Rasmund“ brachte den Alltag vieler Berliner durcheinander.
[online] Available at: https://www.berliner-zeitung.de/berlin/jahrhundertregen-tief--rasmund--brachte-den-alltag-vieler-berliner-durcheinander-27889694 [25 June 2019]

Die Deutschen Versicherer. 2015. Sach­ver­si­che­rer zahl­ten zwei Mil­li­ar­den Euro für Stürme, Star­kre­gen und Hagel. [online]
Available at: https://www.gdv.de/de/medien/aktuell/sachversicherer-zahlten-zwei-milliarden-euro-fuer-stuerme--starkregen-und-hagel-17936 [25 June 2019]

Die Deutschen Versicherer. 2017. Unwet­ter „Paul“ und „Ras­mund“ ver­ur­sa­chen Schä­den von über einer hal­ben Mil­li­arde Euro. [online] Available at: https://www.gdv.de/de/themen/news/unwetter--paul--und--rasmund--verursachen-schaeden-von-ueber-einer-halben-milliarde-euro-12024 [25 June 2019]

European Academics Science Advisory Council (EASAC). 2018. Extreme weather events in Europe. [pdf] Available at: https://easac.eu/fileadmin/PDF_s/reports_statements/Extreme_Weather/EASAC_Extreme_Weather_2018_web_23March.pdf [25 June 2019]

Gesamtverband der Deutschen Versicherungswirtschaft e. V. 2018. Naturgefahrenreport 2018. [online], Ruksaldruck GmbH + Co. KG. Avaliable at: https://www.gdv.de/resource/blob/36254/23ad47bd6746bc456849b5cd41f61516/naturgefahrenreport-2018---schaden-chronik-data.pdf [25 June 2019]

WeLT. 2015. Wie ein Extremregen ganz Münster umkrempelte. [online] Available at:
https://www.welt.de/regionales/nrw/article144506619/Wie-ein-Extremregen-ganz-Muenster-umkrempelte.html [25 June 2019]

Zeit Online. 2017. Starkregen führt in Berlin zum Ausnahmezustand bei der Feuerwehr. [online] Available at: https://www.berliner-zeitung.de/berlin/jahrhundertregen-tief--rasmund--brachte-den-alltag-vieler-berliner-durcheinander-27889694 [25 June 2019]

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