Coastal transportation infrastructure is undergoing stress due to the effects of climate change, including more frequent storms and sea level rise. Such is the case of Alabama State Route 180 (AL-180), due to its low elevations and its proximity to Mobile Bay (MB) and the Gulf of Mexico (GOM). Numerical modeling is an alternative that is often used in such conditions to evaluate alternatives that could alleviate water stressors to infrastructure. This research presents preliminary numerical modeling results from the US Army Corps of Engineers Gridded Surface and Subsurface Hydrological Model (GSSHA). This model implemented a gridded discretization of the entire Fort Morgan Peninsula with variable water surface elevation boundary conditions for the tide around the peninsula. To study the effect of extreme rainfall episodes, we conducted two 24-hour simulations using two synthetic rainfall events, a 2-year return period (152 mm), and a 10-year return period (228 mm). Our findings revealed flooding of up to 20 cm along certain segments of the road, particularly in areas where the road is nearer MB on the western and central parts of the peninsula, during both rainfall events. However, a significant portion of the rainfall infiltrated into the ground rather than contributing to surface runoff. This can be attributed to the sandy soil in the region, as well as the absence of representation for the water table in the model. In future work shallow groundwater will be incorporated into the model and we will explore related effects in flooding.
