Scientific Peer Review of the IHM Integrated Hydrologic Model for Tampa Bay Water, Clearwater, Florida

Client: Tampa Bay Water and the Southwest Florida Water Management District.
Contact: Dr. Jeff Geurink, Principal Water Resources System Engineer, Tampa Bay Water, 2575 Enterprise Rd, Clearwater, FL 33763,
Key Earthfx Personnel: E.J. Wexler, Spencer Malott, and Dirk Kassenaar
Project Partners: WEST Consultants (Dr. Ray Walton) and Hydrocomp Incorporated (Dr. Norm Crawford)

Tampa Bay Water (TBW) operates 13 wellfields to supply high-quality drinking water to more than 2 million residents in the Tampa Bay Region. To enable Tampa Bay Water and SWFWMD to better manage the water resources of west-central Florida, and recognizing the strong interaction between surface water and groundwater, including wetland connectivity, the agencies have developed a coupled groundwater/surface water model to simulate hydrologic processes in the Tampa Bay area. The model is used to optimize regional operations, conduct water resources assessments, and inform well permitting and supply management.
Earthfx, WEST Consultants, and Hydrocomp Incorporated formed a Scientific Review Team to conduct a thorough and independent review of IHM, to assure TBW, SWFWMD, and future users that the model code accurately simulates the major hydrologic processes in settings with near-surface to deep water table depths, is properly and efficiently coded, is operating correctly, and is comprehensively documented.

The review entailed the following key tasks:

• Evaluate Conceptual Model and Theoretical Background: Review of the integration of HSPF and MODFLOW conceptual models, IHM methods for representing coupled hydrologic processes, and organization and clarity of the IHM Theory Manual

• Evaluate the IHM Source Code: Inspection and review of the code to assess internal workings, consistency with IHM Theory Manual, consistency with IHM Programmer’s Guide, level of internal code documentation, clarity and efficiency of code design and structure, and organization and clarity of IHM Programmer’s Guide

• Validate IHM: Develop ten validation tests focussing on basic and coupled hydrologic processes, test IHM against analytical models and other coupled models, and

• Evaluate the IHM User Guide and User Interface: Critique the clarity, design, and content of the user interface and accompanying documentation, review covering model conceptualization, organization of model input, model development instructions, and simulation processing.

The IHM model is extremely complex and thoroughly documented. The Scientific Review Team thoroughly reviewed the manuals, most of which running several hundred pages in length. Earthfx staff led the technical review and delved deep into the source code, stepped through test problems in the debugger to follow code operations, built test problems from scratch to examine database structures and connectivity, and worked with the many pre- and post-processors developed for IHM.

The Scientific Review Team presented results of its theoretical and technical review of IHM in a written draft report and in meetings with technical staff of TBW and SFWMD. A public workshop was held in Clearwater with other agencies, researchers, and other consultants to discuss the finding regarding the IHM code.