AQUIFER FRAMEWORK MAPPING IN SW FLORIDA: DATA MANAGEMENT, INTERPOLATION, AND STATISTICAL VALIDATION

The goal of the Hydrostratigraphic Framework of the Southwest Florida Water Management District project was to create a detailed series of lithostratigraphic and hydrostratigraphic maps and cross-sections covering the 16 county (16,000 km2) region to facilitate science-based decision making with regard to the protection, conservation, management, and planning of southwest Florida's ground water resources. A total of 34 cross-sections and 22 surface and thickness maps were developed based upon data from 1072 wells. During analysis of continuous cores, well cuttings, existing descriptions, and geophysical logs, a system was implemented to identify vertical uncertainty of unit boundaries. This information was used during 3D spatial analysis to refine the data on which interpolations were based. The ordinary kriging interpolator available with in ESRI's Geostatistical Analyst extension was used to create surface and thickness maps as a series of grids. All 22 grids were analyzed in 3D to ensure correct spatial relations at each stage of the modeling process. Grids were then compared with a 15m DEM to ensure no surfaces exceeded ground surface. In addition, each interpolated grid was subjected to a custom “grid to point” script created to calculate any elevation differences between the mapped value and interpolated cell values. Contour intervals for each mapped unit were determined based upon kriging Prediction Error statistics (Average Standard Error and Root-Mean-Square). The resulting maps provide a better vision and understanding of the geologic and hydrogeologic 3D architecture in SW Florida.