Dramatic hydrodynamic and sedimentary responses in Galveston Bay and adjacent inner shelf to Hurricane Harvey

Hurricane Harvey, one of the worst hurricanes that hit the United States in recent history, poured record-breaking rainfall across the Houston metropolitan area. Based on a comprehensive set of data from various sources, we examined the dramatic responses in hydrodynamic and sedimentary processes of Galveston Bay to this extreme event. Using a freshwater fraction method that circumvents the uncertainties in surface runoff and groundwater discharge, the freshwater load into the bay during Harvey and the following month was estimated to be 11.1 × 10⁹ m³, about 3 times the bay volume, which had completely refreshed the entire bay. Harvey also delivered 9.86 × 10⁷ metric tons of sediment into the bay, equivalent to 18 years of average annual sediment load. At a site inside the San Jacinto Estuary, acute bed erosion of 48 cm followed by deposition of 22 cm of new sediment was observed from the sediment cores. Slow salinity recovery (~2 month) and a thick flood deposit (~10.5 cm average over the entire bay) had likely impacted the ecosystem in the bay and the adjacent inner shelf. Estuaries with similar bathymetric and geometric characteristics, i.e., shallow bathymetry with narrow outlets, are expected to experience similar dramatic estuarine responses while extreme precipitation events are expected to occur more frequently under the warming climate.