Modeling of the Wolf Bay and Perdido Bay Watersheds using HSPF

Abstract

This study is the first stage of the larger project for determining the transport mechanism of endocrine disruptors that flow through the Perdido Bay Basin. Given within are the methods and processes used to perform watershed delineation, determine watershed area and hydrologic and hydraulic connections of subwatersheds and rivers, properties of subwatersheds, and other hydrologic modeling parameters. These were determined by starting with LIDAR raster data to create digital elevation models, then using geographic information systems to create drainage basin networks for eight major watersheds. Hydrological Simulation Program-Fortran (HSPF) models were then developed for these watersheds, and model parameters were specified using HSPFParm and other available data. HSPF models for the Perdido River, Styx River, and Elevenmile Creek watersheds were all calibrated sufficiently. The Hammock Creek, Milflin Creek, and Blackwater River watersheds had no gage data to calibrate with, however models were created and adjusted from default values by using the values from the most similar calibrated model. The Wolf Creek model had partial calibration due to a lack of wastewater treatment plant discharge data availability. Finally, the Marcus Bayou model’s calibration was not satisfactory (low model efficiencies) due to multiple data issues and unique watershed characteristics (e.g., low slope, coastal groundwater effects). This study’s conclusions are that the Perdido, Styx and Elevenmile HSPF models are sufficiently modeled and calibrated and a plan to integrate simulated discharges from HSPF models and unmodeled areas with a hydrodynamic model of Perdido Bay and Wolf Bay was developed. However, more data needs to be acquired to adequately model Wolf Creek and Marcus Bayou. In addition, more sources of water quality data need to be obtained to perform adequate water quality analysis.