AQUA TERRA Consultants
AQUA TERRA Services
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Scientific Review of Integrated Surface and Ground Water Model (ISGW)

Client: WEST Consultants, Inc., Bellevue, WA
Funding: Tampa Bay Water, Tampa Bay, FL

Tampa Bay Water, Florida's largest wholesale water supplier, owns twelve groundwater supply systems which are operated in accordance with permits issued by the Southwest Florida Water Management District (SWFWMD). Eleven of these wellfields are operated as an integrated system by applying a set of simulation/optimization models to minimize environmental impacts while meeting water demand in a cost-effective manner. The eleven wellfields are managed using an integrated surface/ground water (ISGW) hydrologic simulation model. The ISGW model is comprised of the ground water model MODFLOW, the surface water model HSPF, and inter-processor programs that perform calculations of evapotranspiration, build and store data for post-processing, create weekly HSPF input files, and transfer output data between HSPF and MODFLOW.

ISGW has been applied to the Tampa Bay wellfield area continually since 1993; during this period the model has undergone numerous revisions and re-conceptualizations as the application of the model expanded and as the understanding of the hydrologic system improved. In 1998 SWFWMD initiated a comprehensive review of prior ISGW application. A Technical Advisory Committee (TAC) was formed, and its review process lasted until April 1999. It was determined by Tampa Bay Water that a number of the TAC recommendations required further evaluation. Among the desired evaluations was a comprehensive review of the model and its application by an independent source. For this purpose, Tampa Bay Water retained WEST Consultants and its subcontractors.

AQUA TERRA's role in this comprehensive review of the ISGW Model was to perform an independent, detailed scientific review of the surface water (i.e., HSPF) and the surface/ground water linkage components of the model. To do so, we participated in four task areas:

  • Review of model conceptualization, process formulations, linkage theory and approach, and model coding
  • Review and evaluation of the previously performed HSPF application to determine the appropriateness of the model parameters that were used, and the quality of the model calibration
  • Review and evaluation of the use of model results to develop unit response functions and pumping scenarios
  • Participation in technical meetings and preparation of study reports

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