Estimating Ground-Water Exchange with Lakes Using Water-Budget and Chemical Mass-Balance Approaches for Ten Lakes in Ridge Areas of Polk and Highlands Counties, Florida

摘要

This report presents estimates of the amount of ground water in the water budgetsof 10 lakes in Polk and Highlands Counties based on water-budget and chemical mass-balance approaches. Heads in the shallow surficial aquifer system were mapped monthly in the vicinity of each lake to define ground-water head gradients around the lakes and to delineate regions of ground-water inflow and outflow. The head in the deeper Upper Floridan aquifer also was measured monthly near each lake to define the vertical head gradient between the lake and the Upper Floridian aquifer. Lakes and selected wells were sampled three times during the study for major ions, selected trace elements, and nutrients; the isotopes deuterium and oxygen-18 were sampled twice in lakes and selected wells. The chemical mass-balance method was used to independently compute annual ground-water inflow and an outflow using a steady-state approach. Computed ground-water inflow results from the various tracers are presented, and limitations to this approach are discussed.