High‐Resolution Modeling of Future Urban Area and Population Exposure to Floods and Landslides

Abstract Future population growth is expected to concentrate in urban agglomerations that overlap with various natural hazard zones. However, quantifying the resulting risks remains challenging, as hazard areas tend to be bounded locally while population forecasts are produced at much coarser scales. Addressing this gap, the high‐resolution 2UP model disaggregates national‐level, scenario‐based population projections to a 30 arc‐seconds grid, simultaneously simulating urban expansion and the distribution of urban and rural populations through 2100. By overlaying these projections with comparably detailed fluvial flood and landslide hazard data, this study demonstrates that, at a global scale, rapid urbanization will disproportionately increase population growth in hazard‐prone zones compared to safer areas. This trend is particularly pronounced in sub‐Saharan Africa and South Asia, where both the extent of exposed urban land and the magnitude of exposed populations are projected to rise sharply. In contrast, slower growth in North America and Europe leads to more moderate increases in hazard exposure, with smaller differences between hazardous and non‐hazardous sites. Notably, while urban areas in many countries continue expanding into high‐risk regions, the fraction of the total population exposed to these hazards may stabilize or even decline after 2050. The 2UP model's fine‐grained outputs are especially valuable in regions with fragmented urban landscapes, large rural populations, and rapid demographic shifts, providing decision‐makers and researchers with critical insights for integrated risk management and sustainable development planning.