Application of the Method of Galdit for Groundwater Vulnerability Assessment: A Case of South Florida

Abstract

Saltwater intrusion is a growing concern for many coastal regions in Florida. Groundwater pumping in Florida has increased over the past years in order to meet the demand for fresh drinking water.  Groundwater pumping is reducing freshwater flow toward coastal discharge areas and drawing saltwater toward the freshwater zones of the aquifer.  In order to better prepare and mitigate the effects of saltwater intrusion, saltwater intrusion vulnerability maps can be created to indicate areas that may be highly susceptible.  The creation of a saltwater vulnerability map, through application of the GALDIT method, allowed us to identify areas that are highly vulnerable to saltwater intrusion.  The six factors incorporated into assessing saltwater intrusion vulnerability (groundwater occurrence, aquifer hydraulic conductivity, depth to groundwater level, distance from shore, impact of existing seawater intrusion, and aquifer thickness) allow us to numerically rank and map areas of low to very high vulnerability.  The final vulnerability map clearly identified the south eastern portion of Florida as the most vulnerable region in Florida which includes the Miami-dade, Broward, palm beach areas. Strategies need to be defined to manage the long term sustainability of the ground water underneath these critical areas.