Using the USGS Dougherty Plain Groundwater Model for Ensemble Analysis

Abstract

Up to this point, the USGS Dougherty Plain groundwater model has been used primarily to analyze the impact of groundwater irrigation on reduction of groundwater discharge into surface water stream flow. The original hydrologic conditions used in model were based on 2001 dry year data. In this study, additional dry year conditions, 2007, were developed. Effects of the same seasonal groundwater irrigation on stream flow reduction and stream-aquifer flow under 2007 and 2001 dry conditions were simulated and compared. It is found that stream flow reductions under 2007 and 2001 dry conditions are very close on a 10-month average basis and on a monthly basis, while the net flow discharges from the Floridan Aquifer to the streams are different. The net flow discharges are more sensitive to the changes in the modeled hydrologic conditions than stream flow reductions do. Upon data availability, changing the model inputs or boundary conditions can result in a host of potential responses from groundwater aquifers and surface water streams. This may in turn provide more insight when the model is used to advise water resource planning and management.