The Impact of Storm Surges on Groundwater Resources:  A Look at Barrier Islands in the Southeastern United States

This study utilized numerical modeling to investigate the effect of a one in one hundred year storm surge on the salinization of freshwater aquifers of barrier islands on the southeastern coastline of the United States, and to assess the sensitivity of these modeling results to variations in geologic and hydrologic parameters. GIS data of two barrier islands and results from previous studies were used to create a generalized model of the salinization process using the SEAWAT component of the USGS MODFLOW modeling suite. It was found that barrier island aquifers are susceptible to significant salinization since they consist primarily of sand, which exhibits relatively high hydraulic conductivity. Hydraulic conductivity of the local geology and duration of the storm surge inundation were identified as the two strongest governing parameters of salinization processes, producing variations in average saline infiltration depth of up to 2 m or 70%, respectively. Variations of porosity of the soil and water level above land surface were found have a lesser impact on the modeling results. No easily generalized method of prediction for this problem could be derived from the results of this study since the model exhibited a strongly systemic behavior rather than consistent local dependence on variations in the investigated parameters. Recommendations for further study of this behavior and the effects of salinization on barrier island aquifers as a whole are made.