Simulation of Groundwater Flow and Salt Transport in A Shallow Microtidal Barrier Aquifer During A Storm Surge

We use numerical modelling to study the impact of seasonal storm surges on the aquifer-ocean exchange of fluid and salt in a micro-tidal, shallow, heterogeneous, narrow barrier aquifer. The model simulates variably-saturated groundwater flow and solute transport and incorporates dynamic boundary conditions that represent seawater inundation of the beach, seepage-face development, and recharge. Hydraulic aquifer parameters were estimated from field data. Boundary conditions were reconstructed from time-series of sea level, precipitation and salinity. A storm surge that occurred in March 2008 was simulated. The results indicate that for the field settings studied in this paper, the impact of episodic ocean events on the aquifer-ocean exchange of fluid and salt relative to the continuing influence of recharge is limited. Groundwater flow is dominated by a continuing flux of water to the ocean, driven by recharge and the hydraulic gradient between the landside and the ocean.