Water Resources

Protecting Life’s Most Precious Resource – For over 30 years, HGL has been providing a wide range of water resources management services to clients around the world facing both water quantity and water quality challenges. As a leader in innovative environmental and resource management solutions, HGL recognizes that achieving global sustainability will require managing water resources while meeting increasing development and energy needs. HGL’s engineers and scientists use innovative technologies, industry-leading modeling and decision support tools, and best management practices to design cost-effective solutions to manage both water quantity and quality issues for municipalities, regulatory entities, and management enterprises..

HGL’s expertise encompasses the following service areas:

The following projects demonstrate HGL’s expertise in Water Resources:

• Water Resources Modeling Evaluation, for the Apalachicola, Chattahoochee, and Flint (ACF) River Basin, Florida,
• Development and Calibration of a Watershed Hydrologic Model, Florida, and
• Three-Dimensional Saltwater Intrusion Model, for the Tiger Bay, Volusia County, Florida.

Water Resources Modeling Evaluation, for the Apalachicola, Chattahoochee, and Flint River Basin, Florida

For the Northwest Florida Water Management District (NWFWMD), HGL performed a comprehensive analysis of transient stream flow reduction caused by groundwater pumping in the Apalachicola, Chattahoochee, and Flint (ACF) River Basin in portions of Florida, Georgia, and Alabama. The starting point of this analysis was a U.S. Geological Survey (USGS) study that focused on steady-state conditions and addressed seasonal fluctuations in only a limited manner. HGL reviewed the USGS-developed groundwater model, including its adequacy for simulating the Floridan aquifer system and groundwater/surface water interactions. HGL extended the model and performed 55-year transient model simulations for 1995, 2010, and 2050 projections. These projections included both “expected” and “high” demands, as well as “dry” and “normal” conditions. Various future operating conditions were also analyzed for the ACF River reservoir system with respect to water supply and water quality. HGL used the U.S. Army Corps of Engineers’ HEC-5 model, along with a 55-year record of observed daily stream flows to evaluate the upper limits of available water after all reservoir uses, other than flood protection, had been satisfied.

Development and Calibration of a Watershed Hydrologic Model, Florida

 For the Southwest Florida Water Management District (SWFWMD), HGL developed a comprehensive watershed hydrologic model of the area that includes the Northern District Model (NDM) and the SWFWMD-Wide Regulatory Model (DWRM). The model was used to estimate recharge and evapotranspiration based on climatic factors, and the findings were used to improve the calibration and simulation capabilities of the NDM and to provide time-dependent recharge to the DWRM. The calibration of the NDM was refined using the new recharge datasets.

This project comprised two phases. The objective of the first phase was to construct and calibrate HSPF-based models that simulate watershed hydrology and surface water flow in the NDM and DWRM domains. Data used in the development of the models included NEXRAD-based and National Oceanic and Atmospheric Administration-gauged precipitation, U.S. Geological Survey GOES-based ET, landuse, soil types, stream flow time series, and anthropogenic stresses. Calibration metrics, based on specific comparisons between simulated and observed values, included annual and monthly runoff volumes; daily time series of flow; storm event periods (e.g., hourly values); and flow frequency (flow duration) curves. Once calibrated, the models were used to generate recharge for the current steady-state and transient NDM and DWRM. The DWRM was the first calibrated continuous flow surface water model to simulate the hydrology of all the watersheds within and immediately beyond SWFWMD boundaries, accounting for major hydrological processes and infrastructure.

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.