Flood impact demonstrates region’s progress in preparedness as rainfall exceeding 100-year return period resulted in 25-65 years loss for insurers in Czech Republic, Poland and Austria.
Release date: 24/09/2024
Post Event Report: Floods—Central and Eastern Europe
Executive Summary
The estimated market losses from the September 2024 floods stand between EUR 1.6 billion and EUR 2.1 billion. Although the region faced significant rainfall and flooding, the damage in real terms is notably lower than previous events, such as the major floods of 1997 and 2002. This reduction in losses is largely due to improved flood risk management and heightened public awareness across the region. Investments in flood defenses and timely preventive measures such as pre-emptive predicative reservoir management and reinforced levees, alongside more accurate early warning systems, played a key role in minimizing the financial impact and safeguarding major urban centers.
Hydrometeorological Assessment
This event was characterised by large-scale circulation patterns which caused a prolonged period of heavy rainfall. This led to widespread flooding across Central Europe.
Large meanders in the jet stream resulted in a wave of cold air plunging southwards from the Arctic across Europe. This cold air clashed with warm moist air coming off the Mediterranean and Black Sea. High-pressure systems over Western and Eastern Europe blocked a surface low pressure system from moving away from Central Europe.
Precipitation developed along the warm/cold boundary which was held near stationary due to high pressure blocking either side. The precipitation was enhanced by orography across Central Europe which caused the moist air to rise and cool over mountainous terrain and release further precipitation. Warm sea surface temperatures from a hot summer over the Mediterranean and Black Sea wrapped around the storm like a river of moist air, continually supplying the storm with fuel.
The IMERG satellite-derived precipitation 7-day accumulations showed large areas of 200mm+ accumulations across the Czech Republic, Austria and Southeast Germany. On the ground, some observations of rainfall totals reached over 400mm for multiple rain gauges in the Czech Republic since Thursday, 12 September, peaking on the morning of Monday, 16 September. Rainfall totals of 454mm and 440mm were observed in Labská Bouda and Jeseník respectively, with 24-hour precipitation of 203.4mm on Saturday, 14 September. The ERA5 100-year return period median 24-hour rainfall accumulation for the period 1989–2018 is 67.9mm for the Czech Republic, with many of the rain gauges across the country exceeding this.
Historical Events
2002
Forecast maps show many similarities to the floods of 2002 which led to devastating floods for Austria, the Czech Republic and parts of Germany. That event was the result of a Vb-type cyclone named Ilse causing a multi-day flood event that overwhelmed the Elbe and Danube catchments. Here we saw very humid air, advected from the Mediterranean Basin around the eastern Alps. A frontal zone stalling over the affected area for a significant amount of time and airflow up the Central European mountains aided the cooling of the air that resulted in heavy rainfall. The event resulted in intense rainfall of around 320mm over 2 days in the Erzbirger Mountains.
1997
In 1997, both the Oder and the Vistula rivers swelled to levels that had return periods in the 1000s of years. The event saw peak rainfall of 585mm between 4 and 9 July (recorded at a mountain site).
The flooding was associated with an upper cut off low over Southeast Europe. The cyclone track was similar to the current event as the surface low tracked from the Mediterranean to Central Europe near the eastern Alps (Vb track).
Vb tracks have potential to lead to extreme rainfall due to their advection of humid air, frontal uplift and flow up the northern slopes of the Alps—all ingredients for high intensity rainfall. When this combines with slow-moving upper-level dynamics, such as blocking, these can cause multi-day events with continual moisture supply and lifting mechanisms, hence the high accumulations seen in these scenarios.
Climate change
Global warming is expected to increase the frequency and severity of intense rainfall events, potentially leading to an increase in flash flooding events. The occurrence and impact of these events are affected by circulation patterns, antecedent conditions and local terrain. Other factors also play an important role in present and future changes in flood losses, including exposure growth, urbanization and concentration of risk, changes in land use, improvements in flood defenses and changes to building practices, amongst others.
Impacts
Swathes of Austria, the Czech Republic, Hungary, Romania and Slovakia have been heavily affected by high winds and severe rains since 11 September. Eight people have drowned in Austria, Poland and Romania, and 4 others are missing in the Czech Republic, as Storm Boris lashed Central and Eastern Europe, bringing torrential rain and floods that have forced the evacuation of thousands of people from their homes.
Austria
The province of Lower Austria has been declared a catastrophe zone, with emergency services making nearly 5,000 interventions where flooding had trapped residents in their homes. The residents in approximately 24 villages in the region have been evacuated. Rail services have been suspended in the country’s east, with similar disruption across the metro services in Vienna.
The whole of Lower Austria has now been declared a disaster area. In terms of infrastructural damage, the A1 motorway near St. Pölten was flooded and partial closure of the Western Railway line (the most important W-O connection) and disruptions to the Vienna subway and other train services have been reported. There have also been repeated power outages in Vienna and the Lower Austria District of St. Pölten (Harland) and the Alpine train station is under water.
Additionally, Danube tributaries overflowed their banks (Kierlingbach, Triesting, Wienfluss, Göllersbach, Erlauf, Kamps).
Poland
Approximately 1,600 people have been evacuated in Kłodzko in Lower Silesia, which was partly under water as the local river rose to 6.7 meters due to the Poplar retention reservoir failure near the village of Kozielno on the Nysa Kłodzka River. As a consequence, the center of Kłodzko was fully flooded. Further floods have been recorded in the Jelenia Góra region. In terms of infrastructural damage in Nysa, a hospital has been evacuated and the viaduct in Lądek Zdrój collapsed. In terms of dam breaches, overtopping has been recorded in Pilchowice and there was a dam breach in Stronie Śląskie.
As a new prevention measure, the Racibórz Dolny reservoir was launched. The reservoir receives water rising from the Oder River. Its purpose is to lower the valves of the overflow and drain structure, with the ultimate goal of protecting cities like Kędzierzyn-Koźle, Opole, Wrocław and smaller towns.
Hungary
Officials have raised forecasts for the Danube to rise above 8.5m, nearing the record 8.91m seen in 2013.
Romania
Six people have died in floods in the southeast. In the worst-affected region, Galati in the southeast has seen nearly 5,000 homes damaged. According to ISU Galați, the areas most affected by the floods are the villages of Pechea, Cudalbi, Costache Negri, Slobozia Conachi and Cuza Vodă, where residents have requested water to be pumped out from their yards. Several people were trapped in their homes due to the water and debris brought by the floods, and there were requests for hospital transportation due to various medical conditions.
Czech Republic
Large parts of the Czech Republic have been affected as authorities declared the highest flood warnings at more than 260 locations across the country. At more than 55 locations, 100-year flood levels were recorded. The most heavily impacted region was Moravskoslezsky kraj, where flooding hit larger towns such as Ostrava, Opava, Krnov, Jesenik and Bohumin. More than 15,000 people were evacuated in this region, and electricity, heating and drinking water suppliers have been interrupted. On Sunday morning, 15 September, around 250,000 inhabitants were without electricity. Transport infrastructure was damaged, including roads, highways and railways. A tree fell as a result of the strong wind. Two landslides were reported, one in the Krkonose mountains and another in Valasske Mezirici.
In Ostrava, flood defenses were breached and many industrial risks were flooded, including chemical plants BorsodChem and OKK Koksovny. In other towns, beverage producers (Kofola in Krnov, breweries in Hanusovice and Litovel), a pharmacy plant (Teva in Opava) and a food producer (Bidfood) were flooded.
Slovakia
Slovakia is less impacted than other countries. Minor to moderate flood losses are reported in Stupava, Nové Zámky, Bratislava and Myjava.
Germany
Low impact.
Source: McKenzie Intelligence Services and other press articles
Similarity Analysis with 1997 Event
Methodology
McKenzie Intelligence Services published their first view on the impacted areas by producing both a 1km exposure layer and a 50m claims layer. The claims layer is meant to be a refinement of the exposure layer and act as a better predictor of where claims are likely to occur.
Data was acquired/downloaded from the Copernicus Emergency Management Service (European Union, 2012–2024) EMSR756/757/758.
The values for estimated flood depth grading are:
- Light Flooding: maximum depth above 0m and below 0.5m (1ft).
- Moderate Flooding: maximum depth above 0.5m (1ft) and below 1m (3ft).
- Severe Flooding: maximum depth above 1m (3ft).
The current footprints are likely underestimated and will evolve over the coming days. At this point, this exhibit can be refreshed easily as new footprints become available from any source.
Market Severity Results
Table assesses the number of affected buildings against MIS footprint based on exposure layer.
The assessment of the number of buildings is benchmarked against flooded area (km²), persons affected and death toll. Figures are respectively illustrated in Tables 3 and 4.
Sources: Population estimated from 400m Kontur population layer. Buildings estimated from Overture Buildings layer.
Comparison and Conclusion
Unlike the devastating floods of 1997, 2001, 2002 and 2010, the impact of the 2024 flood was significantly mitigated by modern infrastructure, dams and flood barriers. Moreover, advancements in weather forecasting played a crucial role in minimizing damage, as more accurate and timely predictions allowed for increased preparedness and swift emergency responses. In the case of the Czech Republic, reservoirs on the Vltava River were strategically drained ahead of the flood, creating additional storage capacity to absorb the rising waters.
Similarly in Poland, the Racibórz Dolny reservoir was launched as a new prevention measure, with the ultimate goal of protecting cities like Kędzierzyn-Koźle, Opole, Wrocław and smaller towns. These proactive measures, backed by scientific improvements, underscore the region's progress in protecting communities and economies from extreme weather events.
Based on currently available footprints, flood metrics for the number of affected buildings and flooded area in the Czech Republic and Poland show ratios between 1:4 and 1:3 when compared with the 1997 events.
Despite the severity of the event, Guy Carpenter’s preliminary estimates place the impact on the aggregate insurance market between EUR 1.6 billion and EUR 2.1 billion, and on a country level for most affected territories as follows:
Austria: EUR 550–650 million
Czech Republic: EUR 600–750 million
Poland: EUR 350–550 million
Slovakia/Hungary/Romania: EUR 100–150 million
Although the nominal value may exceed that of 1997 due to inflation, in real terms, it remains lower. Overall, the 2024 event does not reach the magnitude of the 1997, 2002 and 2010 events, either in terms of rainfall intensity or the resulting financial damage. Early assessments indicate a significantly reduced number of affected properties — approximately 20% of those impacted in 1997 — and overall financial damages are expected to be lower than the 2010 event.
Note that forecasts are uncertain, and actual losses experienced may differ significantly from those estimated. Guy Carpenter will continue to monitor the event and provide further updates if required.
Contact Details
Be sure to visit www.guycarp.com/solutions or contact us to learn more about our offerings, including:
