Three-Dimensional Saltwater Intrusion Model, for the Tiger Bay, Volusia County, Florida


The Tiger Bay area within Volusia County has been identified as a Priority Water Resource Caution Area because of its predicted inability to meet 2025 water-supply demands from traditional groundwater supply sources without unacceptable impacts on water quality, wetlands, and other natural resources. The St. Johns River Water Management District (SJRWMD) contracted HGL to develop a groundwater flow and density-dependent saltwater intrusion model to provide an essential analytical and management tool for evaluating increases in groundwater withdrawals and water quality trends. For the purposes of the Water Supply Assessment, SJRWMD evaluated water quality trends and increases in groundwater withdrawals. To make the evaluation process inclusive of potential saltwater intrusion, HGL developed a density-dependent groundwater flow and transport model. The developed model was used to assess the extent of potential saline intrusion under different water management scenarios.

Project Highlights
Developed a groundwater model that spanned approximately 24 miles in an east-west direction and 34 miles in a north-south direction, incorporated the salient sub-regional hydrogeologic influences within the Tiger Bay area based on available published data from several sources, including SJRWMD, the U.S. Geological Survey (USGS), and the National Oceanic and Atmospheric Administration.
Used the USGS SEAWAT-2000 code as a simulator for density-dependent groundwater flow and transport in the model region.
Calibrated the model in two stages: predevelopment calibration (circa 1936) and transient calibration (1936 to present).
Used the calibrated model to perform a predictive simulation to evaluate the effects of projected pumping rates.
Conducted sensitivity analyses to assess the range of predictive uncertainty of the model.