Compound flooding is induced by coastal storm surge and maintained simultaneously by riverine flooding and a combination of different sources. A 3D coastal ocean model SCHISM (Semi-implicit, Cross-scale, Hydroscience Integrated System Model) coupled with the National Water Model (NWM) was used to simulate Hurricanes Hugo (1989), Joaquin (2015), and Matthew (2016) in the Charleston Harbor and Savannah River Watersheds. An unstructured grid, whose domain covered the US East and Gulf coasts with finer resolution along the South Carolina and Georgia coastlines, was generated. The astronomic tide was forced at the open boundary condition located along 60 degrees west longitude. The atmospheric forcing data used was obtained from the European Center for Medium-range Weather Forecast. Hurricane Hugo was strongly influenced by the powerful storm surge from the ocean and was found to not be an ideal example of compound flooding because the river discharge plays a relatively minor role on the surge of the flood water level. Hurricane Joaquin shows a broad flood signal with both storm surge and riverine forcing driving the flood, which is typical of compound flooding. A compound flooding signal was also found in Hurricane Matthew; however, it did not extend all the way downstream to the coast. In all three cases, when both storm surge and riverine forcing were implemented, it was found that the modeled water level compared favorably to the observational data. This demonstrates that different mechanisms driving compound flooding can be modeled either combined or separately using the framework of the joint SCHISM/NWM model, a milestone for integrating fluvial and storm surge induced coastal flooding.
Maldonado, Breanna, "Numerical Modeling of Compounding Flooding During Hurricanes in the Charleston Harbor and Savannah River Watersheds" (2021). Geology Senior Theses. William & Mary. Paper 2.
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