Tropical cyclone-induced storm surge is a major coastal risk, which will be further amplified by rising sea levels under global warming. Here, a computational efficient is presented, globally applicable modeling approach in which ocean surge and coastal inundation dynamics are modeled in a single step by the open-sourcesolver GeoClaw. This approach is compared to two state-of-the-art, globally applicable approaches:
- using a static inundation model to translate coastal water level time series from afull-scale physical ocean dynamics into inundated areas, and
- a fully static approach directly mapping wind fields to inundation areas.
Four modeling frameworks translating tropical cyclone storm surge into coastal flood extents are compared: (i) the shallow-water equation solver GeoClaw employs storm track data to dynamically calculate coastal water level time series (hydrographs) and coastal flood extents in a single modeling step (GeoClaw, bold solid lines), (ii) the full-scale physical ocean model GTSM is used to calculate coastal hydrographs from meteorological reanalysis data (ERA5), which are then employed to calculate inundated areas with the static inundation model Aqueduct (GTSM + Aqueduct, dottedlines), (iii) the fully static flood module implemented in CLIMADA employs a statistical-surge relationship to translate storm track data directly into flood extents (CLIMADA, thin solid lines), (iv) to test the impact of dynamically resolving inundation processes, the static Aqueduct model is driven by GeoClaw’s coastal hydrographs tocalculate coastal flood extents (GeoClaw + Aqueduct, dashed lines). Arrows indicate the order in which the different models are executed.
For a global set of 71 storms, the modeled flooded areas are compared to satellite-based floodplain observations.
It is found 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.
Reference: Vogt, T., Treu, S., Mengel, M. et al. Modeling surge dynamics improves coastal flood estimates in a global set of tropical cyclones. Commun Earth Environ 5, 529 (2024). https://doi.org/10.1038/s43247-024-01707-x
