Nested Hydrodynamic Modeling of a Coastal River Applying Dynamic-Coupling

摘要

This paper presents a nested hydrodynamic model of the Fish River, a tributary of the sub-estuary Weeks Bay located in Mobile Bay, Alabama. The Environmental Fluid Dynamics Code (EFDC) and a novel dynamic-coupling tool were used to link three EFDC hydrodynamic models corresponding to Mobile Bay, Weeks Bay, and the Fish River. The dynamically-coupled models were used to simulate inundation scenarios for combinations of 2-, 7.5-, 10-, 25-, and 100-year floods, and the hurricane surge that occurred during hurricane Katrina. The nested and dynamically-coupled model was developed using available public-access bathymetry and topography databases (National Elevation Dataset, and NOAA bathymetry), and run without recurring to calibration techniques. The simulation of combined scenarios showed that inundated areas increase from 0.07 up to 189 with respect to the actual flood that took place during the Katrina event (Katrina+1-year flood). The results suggest that increases in inundated area are relatively much higher from a 1-year flood to a 7.5 year-flood (128 flooded area increase) than for higher return periods. For the 25-year and the 100-year floods, inundated areas almost triple from the area corresponding to the base-case (Katrina event), with percent increases of 182 and 189 respectively.