River Floods

This technical policy briefing note from the ClimateCost project assesses the potential economic impacts of river flooding in the European Union (EU27) under different climate and socio-economic scenarios. Using the LISFLOOD model, the study evaluates expected annual damage (EAD) and the number of people affected (EAP), while analyzing the costs and benefits of maintaining flood protection levels. The findings emphasize that socio-economic growth is as significant a driver of future flood costs as climate change, and that adaptation can significantly reduce direct damages.

• Under the A1B medium-high emission scenario, the number of people potentially affected by river flooding (EAP) in the EU27 is projected to rise from a baseline of 167,000 per year to 300,000 by the 2020s and 359,000 by the 2080s. The marginal impact of climate change alone is estimated to add 130,000 people per year by the 2020s and 2050s, and 210,000 per year by the end of the century.
• Expected annual damage (EAD) from river floods in the EU27 under the A1B scenario is projected to increase from a baseline of €5.5 billion to €20.4 billion by the 2020s, €45.9 billion by the 2050s, and €97.9 billion by the 2080s. The marginal effect of climate change alone is estimated at €9 billion/year by the 2020s, €19 billion/year by the 2050s, and €50 billion/year by the 2080s.
• Socio-economic drivers, specifically population and economic growth, are as important as climate change in determining future flood damages. Under the A1B scenario, socio-economic change alone (without climate change) would increase EAD to €11.5 billion by the 2020s, €27.0 billion by the 2050s, and €47.8 billion by the 2080s.
• Under the E1 mitigation scenario (aligned with the EU 2 degrees target), the projected EAD for the EU27 is €14.6 billion by the 2020s, €41.7 billion by the 2050s, and €68.2 billion by the 2080s. While this is lower than the A1B scenario, the report notes that these results are based on a limited number of climate data sets and may be more related to climate model choice than mitigation effects.
• The majority of flood losses are concentrated in the residential sector, accounting for approximately 82% of the EU27 EAD. Other sectors include industry (7%), commerce (5%), agriculture (just under 5%), and transport (1%).
• Climate-related flood costs vary significantly by country, with the highest increases seen in the UK, Ireland, Italy, the Netherlands, and Belgium. In some regions, such as the Vistula and Odra catchments in Poland, climate change may reduce spring floods due to less snow accumulation but increase summer flooding.
• Maintaining 1 in 100-year flood protection levels across the EU27 under the A1B scenario would provide benefits (avoided damages) of €8 billion/year by the 2020s, €19 billion/year by the 2050s, and €50 billion/year by the 2080s. However, significant residual damages would remain, suggesting that higher protection levels may be justified.
• The estimated annual costs to maintain minimum 1 in 100-year protection levels in the EU27 under the A1B scenario are €1.7 billion by the 2020s, €3.4 billion by the 2050s, and €7.9 billion by the 2080s. An average benefit-to-cost ratio of 4 to 1 was found across European studies.
• A hedonic price study in Prague, Czech Republic, found that flood risks significantly reduce property values, with a central estimated value of -8.5% for houses in the flood-risk zone.
• There is high uncertainty in flood risk projections, with different climate models sometimes projecting opposite directions of change at the local level. This necessitates an iterative and flexible approach to adaptation, prioritizing robust and flexible measures over rigid 'hard' engineering.

APA

Feyen, L., & Watkiss, P. (2011). River Floods. Stockholm Environment Institute. https://www.sei.org/mediamanager/documents/Publications/sei-climatecost-river-floods.pdf

Chicago

Feyen, Luc, and Paul Watkiss. River Floods. Stockholm Environment Institute, 2011. https://www.sei.org/mediamanager/documents/Publications/sei-climatecost-river-floods.pdf.

Wikipedia

{{cite report |last1=Feyen |first1=Luc |last2=Watkiss |first2=Paul |title=River Floods |publisher=Stockholm Environment Institute |date=September 2011 |url=https://www.sei.org/mediamanager/documents/Publications/sei-climatecost-river-floods.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{feyen2011river, author = {Feyen, Luc and Watkiss, Paul}, title = {{River Floods}}, institution = {Stockholm Environment Institute}, year = {2011}, month = sep, url = {https://www.sei.org/mediamanager/documents/Publications/sei-climatecost-river-floods.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }