洪水暴露演变中的城市扩张和保护差距（英）

11321 Urban Expansion and Protection Gapsamid Evolving Flood Exposure Jun RentschlerChristoph KlaiberMengjue ZhuMattia Marconcini Urban, Disaster Risk Management,Resilience and Land Global DepartmentFebruary 2026 A verified reproducibility package for this paper isavailable athttp://reproducibility.worldbank.org,clickherefor direct access. Policy Research Working Paper11321 Abstract Flood risk is increasing globally as climate change interactswith urban expansion and land-use decisions in flood zones.Using a nationally consistent, high-resolution assessment,this study analyzes how settlement growth, climate change,and flood protection shape the evolution of flood expo-sure across more than 11,000 municipalities in Germany,revealing exposure dynamics relevant to many advancedeconomies. The study integrates biannual settlement foot-print data from 2016 to 2025 with fluvial, pluvial, andcoastal flood hazard data, future climate scenarios, anddetailed dike protection maps. The results show that inseveral regions the growth of settlements in flood zones has outpaced that in safe zones, thus reinforcing rather thanreducing exposure. Climate change is projected to increaseflood exposure substantially by late century, particularlyunder high-emissions scenarios, with pluvial flooding beingthe dominant driver of future exposure growth. The studyidentifies substantial mismatches between exposure andstructural flood protection, with many highly exposed areaslacking engineered defenses. The findings underscore howmisalignment between urban development, climate adap-tation, and protection investment can drive rising floodrisk, with implications for land-use planning and resiliencestrategies. This paper is a product of the Urban, Disaster Risk Management, Resilience and Land Global Department. It is part ofa larger effort by the World Bank to provide open access to its research and make a contribution to development policydiscussions around the world. Policy Research Working Papers are also posted on the Web at http://www.worldbank.org/prwp. The authors may be contacted at jrentschler@worldbank.org. A verified reproducibility package for this paper isavailable athttp://reproducibility.worldbank.org, clickherefor direct access. The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about developmentissues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry thenames of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely thoseof the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank andits affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent. Urban Expansion and Protection Gapsamid Evolving Flood Exposure Jun Rentschler,1Christoph Klaiber,1Mengjue Zhu,2Mattia Marconcini3,4 1The World Bank, Washington DC, USA2Georgia Institute of Technology, Atlanta, USA3German Aerospace Center (DLR), Munich, Germany4Mindearth, Biel, Switzerland Acknowledgments This study was supported by the Technical Assistance Financing Facility (TAFF), financed by theEuropean Commission—Directorate-General for European Civil Protection and Humanitarian AidOperations (DG ECHO)—and implemented by the World Bank and the Global Facility for DisasterReduction and Recovery (GFDRR). This technical assistance was delivered in partnership with theGerman Federal Office of Civil Protection and Disaster Assistance as part of the 2024 TAFF allocationfor country-specific activities, under the title “Return of Investments in Disaster Resilience Measures:Identifying measures & generating evidence to inform decision-making in Germany”. The studybenefited from feedback from Peter Ellis, Bramka Jafino, and Zuzana Stanton-Geddes. 1.Introduction Overthe past years, flooding has become an increasingly significant concern in Germany,exacerbated by changing risk profiles due to climate change, land use change, soil sealing, andsettlement growth. These factors collectively contribute to heightened flood risks and changing floodhazard zones, posing substantial threats to both the population and economy. Combined withexisting vulnerabilities—such as, but not limited to, low adaptive capacity, old or damagedinfrastructure, remoteness, and high poverty rates—this can exacerbate the devastating impacts offlood events. This was exemplified by the devastating Ahrtal flood event in July 2021, which resulted in significantloss of life and extensive damage to infrastructure; the flashflood in Braunsbach in 2016; and thewidespread flooding in southern Germany in 2024. These events highlight the urgent need foreffective flood risk management strategies. Climate change is altering precipitation patterns, leadingto mor