Author(s): Louis H. Motz
Linked Author(s): Louis H. Motz
Keywords: Nalytical solution; Confining unit storageevapotranspiration; Groundwater hydraulics; Laplace solution; Pumping impacts; Stehfest algorithm
Abstract: A semi-analytical coupled aquifer model, which calculates transient drawdowns in two coupled aquifers with confining unit storage and drawdown-dependent evapotranspiration reduction, was used to evaluate the drawdown impacts due to pumping from the upper Floridan aquifer at the Cross Bar Ranch well field in west-central Florida, U. S. A. The results indicate that drawdowns in the upper Floridan aquifer reach an apparent steady-state condition in approximately five days but then increase with time as drawdowns in the unpumped surficial aquifer become significant. The total time to reach steady state in the surficial and upper Floridan aquifers is approximately 2800 days. The results are consistent with a post-audit of the Cross Bar Ranch well field that was conducted using a numerical groundwater flow model. The analysis using the coupled aquifer model confirms that the time for the surficial aquifer in the Cross Bar Ranch well field to respond fully to pumping from the underlying upper Floridan aquifer is on the order of several years, and it indicates that the response time increases if confining unit storage is present.
Year: 2001