Local damages drive network-wide costs in compound flood-prone coastal city

This study integrates compound flood modeling with microscale traffic simulations, showing that neighborhoods with minimal inundation can nonetheless face severe gridlock and up to tenfold increases in vehicular emissions. Concurrency of extreme rainfall, river surges, and elevated tides can produce compound floods that single- or multi-hazard summation models frequently misrepresent flood extent and depth-particularly in the Global South, where rapid urban expansion intensifies infrastructure stress.

This discrepancy in indirect costs risks substantial misallocation of limited resources and underscores the broader socio-economic burdens often overlooked by conventional flood risk frameworks. By capturing these correlated hazards and real-time road closures, the authors highlight the need for multihazard flood governance that effectively addresses both localized inundation and network-wide disruptions in rapidly urbanizing coastal cities. While this study focuses on Kozhikode, India, the coupling framework we present is readily adaptable to coastal cities worldwide. The key aspects of the framework-including flood hazard modeling, road network impacts, and user cost calculations-are transferable to a variety of urban areas with diverse geographic and socio-economic conditions.