Impact of Natural Disasters on Flooding: An Assessment Using Satellite Data and Surface-Subsurface Modeling

Dealing with large watersheds sometimes becomes challenging, especially when simulating the surface water-groundwater (SW-GW) interaction within the floodplain. Using satellite data (such as land cover, topography, bathymetry, soil zones, imagery, etc.) can be an excellent way to characterize the surface and subsurface properties to handle large basins, especially those suffering drastic changes due to natural disasters. This study employs satellite data from 2016 and 2019 to develop integrated SW-GW models, aiming to assess the impacts of changes in basin characteristics on surface-subsurface hydrology and flooding. The model was then used to evaluate the flooding impact due to Hurricane Michael (of 2018) in a 437 km2 watershed. Satellite data showed significant changes in hydrologic conditions including tree loss in the study area due to Hurricane Michael. Results for a 25-year 24-hour storm show a 256% increase in flood inundation areas due to the impact of Hurricane Michael. The model could pinpoint locations vulnerable to flooding due to the change in the hydrologic condition of the watershed. Among the 92,206 nodes generated by the model, the most vulnerable flooding location showed 1.9 m excess flooding in the post-hurricane affected area compared to its pre-hurricane condition. Additionally, the SW-GW model accurately tracked stage changes at a gauge station during a 2.5-hour (54.6 mm) storm in March 2022.