FLORIDA AQUIFER VULNERABILITY ASSESSMENT (FAVA): UTILIZING GEOLOGIC MAPPING DATA TO PREDICT AQUIFER VULNERABILITY
Weights of Evidence quantifies relationships between spatial layers with actual contaminant occurrences in order to assess a hypothesis. Contaminant source data (i.e., training points) is obtained from the Florida Department of Environmental Protections Background Water Quality Network of wells. Spatial layers (i.e., evidential themes) consist of existing and newly developed GIS data and include depth to water, soil drainage, distance to karst features, thickness of confinement and vertical leakage rates. Different evidential themes are utilized based on the aquifer being modeled. The evidential themes included in the Floridan aquifer system (FAS) model, for example, are thickness of confining unit, distance to karst features and soil drainage. To aid in the creation of these themes, data collected during geologic mapping projects (e.g., cores, well cuttings, and wireline logs) are utilized. By calculating the statistical significance between training points and evidential themes, interactions can be analyzed to yield a data-driven predictive model. The output is a grid-based probability map that can be used by environmental, regulatory and planning professionals to facilitate the protection of Floridas ground-water resources.