Investigation of the Impacts from Land Subsidence and Land Use on Urban Flooding in the Houston - Galveston Region

The Houston-Galveston region experiences land subsidence as early as the 1900s and, many studies suggest that land subsidence is relevant to worsened flood inundation in the region over the past twenty years. To gain a better understanding of the impacts of land subsidence on flood inundation, the authors conduct research on evaluating flood characteristics in the watersheds of Addicks, Barker, and Buffalo Bayou in the region, using a hydrodynamic/hydraulic 2D model. The model is first developed and calibrated based on observed stage hydrographs and highwater marks from several severe storms occurring in the region including Hurricane Harvey (2017). Ten (10) flood inundation scenarios with different land elevation conditions from multiple years (1900, 1930, 1945, 1960, 1970, 1980, 1990, 2000, 2010 and 2017) are simulated once the model is fully validated. To further investigate the impacts from the land use on flood inundation, various land use scenarios of the past years are simulated for deciphering flood characteristics with respect to the impacts from land subsidence and land use changes. The simulated results are visualized, quantified, and further analyzed in different portions of watersheds, suggesting that flood depth difference reaches its climax in 1980s on the west side of Houston. This is found in accordance with where the land subsidence rate is the highest during the same period.