Urban Expansion and Protection Gaps amid Evolving Flood Exposure

Flood risk is increasing globally as climate change interacts with 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 exposure across more than 11,000 municipalities in Germany, revealing exposure dynamics relevant to many advanced economies. The study integrates biannual settlement footprint data from 2016 to 2025 with fluvial, pluvial, and coastal flood hazard data, future climate scenarios, and detailed dike protection maps. The results show that in several regions the growth of settlements in flood zones has outpaced that in safe zones, thus reinforcing rather than reducing exposure. Climate change is projected to increase flood exposure substantially by late century, particularly under high-emissions scenarios, with pluvial flooding being the dominant driver of future exposure growth. The study identifies substantial mismatches between exposure and structural flood protection, with many highly exposed areas lacking engineered defenses. The findings underscore how misalignment between urban development, climate adaptation, and protection investment can drive rising flood risk, with implications for land-use planning and resilience strategies.