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Study Yields Robust Carrying Capacity Model

CCIAM has built-in checks that ensure each land use scenario is valid. For example, the program will first check that at least one parcel meets the Change From criteria before the user can progress to the Change To criteria. Full execution of a single land use scenario will generate approximately 1 GB of data and, depending on the complexity of the land use changes and GUI selections, take from three to eight hours to complete. The minimum specifications for stand-alone desktop personal computers running scenarios are listed below in Table 2.

Platform Pentium 4, 1.7 GHz
OS Windows 2000
Memory/RAM 512 MB RAM
Hard Drive Space 20 GB
Other Tape backup system or equivalent
Table 2: Minimum specifications for stand-alone desktop personal computers

Performing Analysis

The analysis section of CCIAM is the heart of the application and requires the bulk of the processing time. The scientific models developed by each team of experts were programmed into CCIAM using VBA and complex SQL queries executed by the Jet OLEDB 4.0 database engine. The ability to use SQL queries greatly reduced and simplified the VBA coding required. The analysis tasks accomplished by CCIAM to perform the SQL statement "calculate storm water loads," listed below in Table 3, furnish a good example of functionality.

Tasks Accomplished by CCIAM
A copy of the land use (parcels) coverage is created and the attributes are changed based on the GUI selections.
New land use coverage is imported into the scenario geodatabase.
Terrestrial grid analysis is completed.
Terrestrial vector analysis is completed.
Water analysis (storm water, wastewater, and groundwater) is completed.
Water layer files are created.
Socioeconomic analysis is completed.
Fiscal analysis is completed.
U.S. 1 level of service analysis is completed.
Hurricane evacuation model executes (Excel model).
Canal impact models execute (Excel models).
Table 3: Storm water surface loads SQL statement for uplands.

All CCIAM analysis results (tables and feature classes) are saved in one of five Access geodatabases while the grids are saved in a grids directory. The details and complexity of each analysis module are documented in the FKCCS Maintenance Manual (March 2003), and additional information regarding the assumptions, mathematics, and rationale for CCIAM can be found in the delivery order reports and the study's final report.

Reporting the Results

CCIAM creates XML result files, two final reports in HTML format, and JPEG format map files. The Scenario Report is CCIAM's primary reporting mechanism. The Scenario Report is a compilation of carrying capacity indicators and other information that can be interpreted to derive an assessment of the user-defined scenario. It is intended as a stand-alone document that can provide a planner with the information needed to evaluate a scenario. Explanatory text, included in the Scenario Report, assists the planner in interpreting the results produced by CCIAM. The Model Output Listing is a report that compiles all of the outputs generated by CCIAM. The Model Output Listing accompanying the Scenario Report provides supporting information resulting from CCIAM that is organized by CCIAM module and includes limited explanatory text.

To provide an idea of the scope of result reporting, CCIAM output for one land use scenario included 783 JPEG maps, 11 feature classes, 73 tables, 18 grids, 11 Excel spreadsheets, eight ArcMap layer files, and 83 HTML files. The Scenario Report and the Model Output Listing HTML reports are linked to 81 secondary HTML files. The HTML reports package the data from the feature classes, tables, grids, JPEG maps, and Excel spreadsheets.

Unique Challenges

Key challenges in developing CCIAM included addressing the diverse expectations of a multitude of stakeholders, facilitating and integrating the work of multidisciplinary experts, and resolving many complex scientific and technical issues. Over a two-year period, many private and public meetings were held to finalize the various aspects of CCIAM. The ecological importance of the Keys and the high profile nature of this project meant that a large and diverse group of stakeholders was represented at these meetings, and they did not all agree on even the most basic issues. As with any project of this scope, compromises had to be made and stakeholders couldn't get everything on their wish lists.

Formatting and organizing the massive input datasets, as well as performing and testing the many spatial operations performed on, between, and among these datasets, taxed software, hardware, and the patience of programmers, analysts, and task managers. Because it was important to maintain topology among map features, input files had to be in coverage format. Unfortunately, topology was not available in the personal geodatabase when this application was built (although it is now available in ArcGIS 8.3). The work-around involved unioning the land use (parcel) coverage created from the GUI with other coverages, then importing the results into the geodatabases as feature classes.


In the end, all the hard work paid off as CCIAM (FKCCS project) was a winner of the American Council of Engineering Companies 2003 Engineering Excellence Grand Award.

For more information, contact

Steven G. Parker
GIS Programmer/Analyst
URS Corporation, Tampa, Florida

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