This layer shows the vulnerability of Maryland’s aquifers to saltwater intrusion, based on the GALDIT index. GALDIT evaluates vulnerability based on six parameters: groundwater aquifer type (G), aquifer hydraulic conductivity (A), groundwater level above sea level (L), distance from shore (D), impact of present chloride content (I), and aquifer thickness (T). Each parameter is mapped and scored individually, and the results are combined to produce an overall vulnerability index. The index values highlight areas of moderate to high susceptibility to saltwater intrusion, particularly along Maryland’s Eastern Shore, where agriculture is most at risk.
The data is sourced from the Maryland Geological Survey well monitoring networks, the U.S. Geological Survey groundwater geochemical database, and aquifer confinement estimates. The vulnerability assessment was conducted using Esri ArcGIS with Inverse Distance Weighted (IDW) interpolation to create statewide raster layers at a 30x30m resolution.