Integrating borehole logs and aquifer tests in aquifer characterization

Integration of lithologic logs, geophysical logs, and hydraulic tests is cr itical in characterizing heterogeneous aquifers, Typically only a limited n umber of aquifer tests can be performed, and these need to be designed to p rovide hydraulic properties for the principle aquifers in the system. This study describes the integration of logs and aquifer tests in the developmen t of a hydrostratigraphic model for the surficial aquifer system in and aro und Big Cypress National Preserve in eastern Collier County, Florida. Boreh ole flowmeter tests provide qualitative permeability profiles in most of 26 boreholes drilled in the study area. Flow logs indicate the depth of trans missive units, which are correlated across the study area. Comparison to pu blished studies in adjacent areas indicates that the main limestone aquifer of the Tamiami Formation in the study area corresponds with the gray limes tone aquifer in western Dade County and the water table and lower Tamiami A quifer in western Collier County. Four strategically located, multiwell aqu ifer tests are used to quantify the qualitative permeability profiles provi ded by the flowmeter log analysis, The hydrostratigraphic model based on th ese results defines the main aquifer in the central part of the study area as unconfined to semiconfined with a transmissivity as high as 30,000 m(2)/ day. The aquifer decreases in transmissivity to less than 10,000 m2/day in some parts of western Collier County, and becomes confined to the east and northeast of the study area, where transmissivity decreases to below 5000 m (2)/day.