People-Oriented Assessment Framework of Compound Urban Flooding Risks in the Context of Climate Change: A Case Study of Hong Kong

Coastal urban areas face escalating compound flood risks from climate change and sea-level rise, yet conventional risk assessments rarely consider the dynamic nature of urban populations. This study develops a people-oriented assessment framework to evaluate how human mobility patterns influence compound flood risk exposure in coastal cities, taking the Hong Kong’s Kowloon area as a case study. By combining dynamic population distribution patterns with coupled hydrodynamic modeling based on the platform of LISFLOOD-SWMM, we simulated compound flooding events from rainfall and storm surge co-occurrence under multiple scenarios where both factors share matching return periods (50, 100, and 200 years) and different sea level rise conditions (current, +0.5 m, +1.0 m). Results reveal distinct spatial-temporal patterns in flood risk distribution, showing a clear decreasing trend with distance from the coastline, while areas beyond 900 m inland exhibit significant variations between weekday and weekend exposure patterns. Under sea level rise scenarios, weekday flood risk exposure shows consistent increases across all return period combinations, particularly in commercial districts during daytime hours, while residential areas demonstrate elevated risk levels during nighttime periods, highlighting the critical role of land use patterns in temporal risk distribution. These findings emphasize that human mobility significantly influences flood risk profiles in urban coastal areas, varying substantially between day and night, weekdays and weekends, thereby providing crucial insights for urban planners and emergency managers to develop more effective flood management strategies that account for temporal variations in population exposure. This research contributes to advancing adaptive urban planning approaches with a people-oriented focus and enhancing coastal city resilience in the context of climate change and rapid urbanization.