Modeling surge dynamics improves coastal flood estimates in a global set of tropical cyclones

Tropical cyclone-induced storm surge is a major coastal risk, which will be further amplified by rising sea levels under global warming. Here, we present a computational efficient, globally applicable modeling approach in which ocean surge and coastal inundation dynamics are modeled in a single step by the open-source solver GeoClaw. We compare our approach to two state-of-the-art, globally applicable approaches: (i) using a static inundation model to translate coastal water level time series from a full-scale physical ocean dynamics into inundated areas, and (ii) a fully static approach directly mapping wind fields to inundation areas. For a global set of 71 storms, we compare the modeled flooded areas to satellite-based floodplain observations. We find that, overall, the models have only moderate skill in reproducing the observed floodplains. GeoClaw performs better than the two other modeling approaches that lack a process-based representation of inundation dynamics. The computational efficiency of the presented approach opens up new perspectives for global assessments of coastal risks from tropical cyclones.