Modeling Surficial Aquifer Salinization From Extreme Overwash Events Coupled with Sea-Level Rise

Extreme overwash events, such as storm surge accompanying tropical cyclones, coupled with relative sea level rise present major challenges for populations that depend on surficial aquifers for drinking water.  This study models changes in salinity induced by the above processes by utilizing sand column models.  The column model consists of five schedule 40 clear PVC columns measuring 150 cm in height and 10.16 cm in diameter filled with very fine sand.  The columns have sampling ports at 15 cm increments.  The columns are initially saturated with water of a known salinity concentration equivalent to fresh groundwater profiles taken in the Gulfport, MS region (this site is used for its proximity, the water in the surficial aquifer is not used for drinking water) from 2006-2009.  The columns are then put through various climatic scenarios including: 1) a no flow run where a sodium chloride solution with a dye tracer is placed above the saturated sand column and allowed to diffuse through the media; 2) a storm surge/precipitation run using both a dilute sodium chloride solution with a dye tracer that has a concentration that is representative of storm surge during a hurricane event and a fresh water solution representative of recharge; and 3) multiple scenarios based on varying combinations of storm surge frequency and recharge amounts.  The third set of scenarios will consider increasing tidal impacts with time due to varying rates of sea-level rise.  Salinity concentrations will be measured using a Dionex DX-120 ion chromatography unit.