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DEKALB COUNTY, GEORGIA WATERSHED ASSESSMENT |
Client:
CH2M Hill, Atlanta, GA
Funding:
DeKalb County, GA Water and Sewer Division
DeKalb County Water and Sewer Division initiated a watershed assessment for the South River Basin and an engineering study of the existing water pollution control plants operated by the County that discharge to the river. As the watershed is subject to both nonpoint and point sources, the BASINS and HSPF models were selected for use in the watershed modeling portion of the project. AQUA TERRA, under contract to CH2M Hill, was tasked to perform significant portions of the watershed modeling. These included review of watershed characterization and modeling strategy technical memos, calibration of the hydrologic and water quality model, and review of the draft final report.
As a part of preliminary work on the watershed assessment, technical memos were developed outlining the sampling plan and watershed characterization, and the modeling strategy development. AQUA TERRA took an active role in developing these memos, which were essential to setting up the watershed model.
AQUA TERRA was primarily responsible for calibrating the hydrologic and water quality model. This entailed developing the necessary input parameter (UCI) files for HSPF, performing HSPF runs, analyzing the results, and making parameter modifications to improve the model results. Water quality constituents modeled in the study include TSS, DO, ammonia, nitrate-nitrite, ortho-phosphorous, BOD, water temperature, fecal coliform, and metals.
As part of this process, AQUA TERRA used components of the BASINS 3.0 system, namely WDMUtil and GenScn, for pre- and post-processing, respectively. Additionally, we have used HSPEXP, an expert system for HSPF hydrology calibration. Final deliverables of this work included technical memos summarizing assumptions used in development of the model and documenting the model calibration and verification process.
The final task AQUA TERRA performed was a review of the draft modeling report to check for scientific soundness and thoroughness.