Future Changes in Coastal Groundwater Salinity Due to Sea-level Rise and Higher Intensity and Frequency Storm Surge at Assateague Island, MD

Coastal groundwater resources serve as the primary drinking water source for many people around the world. They are increasingly susceptible to salinization from both the inland movement of the freshwater-saltwater interface due to sea-level rise and storm-surge overtopping, which is expected to become more frequent with climate change. In this study, we measured hydraulic head and specific conductance along a transect of seven wells across Assateague Island, MD, and calibrated a 2D variable-density, groundwater-surface water model to a storm surge in October 2019. Using the calibrated model, we tested the effect of projected sea-level rise and storm surge frequency on the mass of salt and the volume of aquifer salinized under both increased intensity/frequency of storm conditions and the combination of increased intensity/frequency of storms and sea-level rise in 2080. Additionally, we investigated how change in frequency of smaller storms impacts the long-term salinized aquifer volume. Preliminary results suggest that by 2080, changes in intensity and frequency of storm surges will have a larger impact than sea-level rise on the salinized volume at Assateague Island, suggesting that the traditional focus on sea-level rise should shift toward storm-surge intensification.