Abstract
This study investigates hydrogeologic controls on a peculiar, poorly studied type of geographically isolated wetland in west-central Florida, USA, locally referred to as “sandhill wetlands.” Their peculiarity lies in their connectivity to a large, regional aquifer, which controls their hydrology and influences their ecological expression. Six wetlands and one wetland-pond complex were examined using geophysical, lithologic, hydrologic, and ecological data. These data were used to configure site-specific hydrogeology, from which two conceptual models were developed. The first model depicts mechanisms of sandhill wetland connectivity to the regional aquifer. Three mechanisms of connectivity are proposed based on the degree and depth of aquifer confinement: 1) direct - due to wetland embedment directly in the unconfined regional aquifer; 2) indirect - due to embedment in a surficial aquifer, where groundwater exchange with the regional aquifer occurs through breaches in the semi-confining unit; and 3) none - due to embedment in a surficial aquifer where groundwater exchange with the regional aquifer does not occur because the semi-confining unit is too deep. The second model conceptualizes fundamental sandhill wetland ecohydrology. It depicts how the geomorphology of a sandhill depression relative to the range of the regional water table determine whether that feature will manifest as a wetland or as a pond, lake, sink, or upland. Findings from both models contribute to the limited understanding of sandhill wetland, pond, and lake ecohydrology and may be used to improve how they are classified, assessed, managed, and preserved as valuable natural resources.
Water table in the surficial aquifer and potentiometric surface of the Floridan Aquifer in selected well fields, west-central Florida, September 1976
