3
Scenario Generator

The Scenario Generator is a tool (using a series of screens, buttons, and menus) that enables users to define land use changes at the parcel level, the planning unit level, and at intermediate scales using the “rubber banding” option. This flexibility is a major strength of the Draft CCAM that will make it useful for numerous planning applications. While the output scale to other modules is principally at the planning unit scale, parcel-level data are evidently output to the Water Module in order to permit aggregation to the catchment level for stormwater and wastewater loadings calculations.

PRESENTING A CONTEXT

The CCAM is meant to be a tool to help decision-makers guide the development and environmental conservation for the future of the Florida Keys. To be both useful and functional, the tool and its background material must be written clearly and must be readily understandable by both decision-makers and lay readers representing a wide range of interest groups. In setting the scene for the CCAM, existing characteristics of the Florida Keys (i.e., land use, economy, demography, travel patterns, etc.) merit ample description. The issues that have precipitated the need for the Carrying Capacity research also demand clarification near the beginning of the project report. Additional essential matters to be presented include: how the tool will be used, who will use it, and with what frequency it will be updated. As of January 2002, both the clarity of text and the details of the context are matters still missing from the Draft CCAM.



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A Review of the Florida Keys Carrying Capacity Study 3 Scenario Generator The Scenario Generator is a tool (using a series of screens, buttons, and menus) that enables users to define land use changes at the parcel level, the planning unit level, and at intermediate scales using the “rubber banding” option. This flexibility is a major strength of the Draft CCAM that will make it useful for numerous planning applications. While the output scale to other modules is principally at the planning unit scale, parcel-level data are evidently output to the Water Module in order to permit aggregation to the catchment level for stormwater and wastewater loadings calculations. PRESENTING A CONTEXT The CCAM is meant to be a tool to help decision-makers guide the development and environmental conservation for the future of the Florida Keys. To be both useful and functional, the tool and its background material must be written clearly and must be readily understandable by both decision-makers and lay readers representing a wide range of interest groups. In setting the scene for the CCAM, existing characteristics of the Florida Keys (i.e., land use, economy, demography, travel patterns, etc.) merit ample description. The issues that have precipitated the need for the Carrying Capacity research also demand clarification near the beginning of the project report. Additional essential matters to be presented include: how the tool will be used, who will use it, and with what frequency it will be updated. As of January 2002, both the clarity of text and the details of the context are matters still missing from the Draft CCAM.

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A Review of the Florida Keys Carrying Capacity Study DESCRIBING THE FLORIDA KEYS AS THE BASIS FOR SCENARIOS The Draft Report depicts the Florida Keys as “anyplace” USA, with few of the nuances that characterize Monroe County’s land use, economy, or travel patterns. The Scenario Generator (Draft CCAM Section 3.1.2) classifies land uses as residential (at three density levels), commercial (retail, office, services, entertainment, hotel/motel, marina, golf course), institutional, and industrial. Little information is provided about the character of the land uses that will be given quantitative dimensions in the scenarios to be tested and that are the components of the model. Based on field observations from Key Largo to Key West, three examples are given below illustrating matters that should be described in considerable detail: (1) Visitor-Dependent Land Use/Economy U.S. Route 1 is the arterial spine of the Florida Keys along which the preponderance of non-residential land uses are arrayed. Commercial land use dominates mile after mile, from the tip of Key Largo to the monument at the base of Key West. These uses include resorts and motels, restaurants and bars, marinas, attractions (e.g., Theatre of the Sea), gift shops, boat yards, dive shops, and scooter and jet-ski rentals along with real estate and other services geared to the tourist industry. Supermarkets, drug stores, and gas stations exist, but appear to be as much oriented to transients as to residents, and they pale in contrast to the large chain shopping centers and department stores at the entrance to the Florida Keys in southern Miami-Dade. Except for local government operations, office space appears to be concentrated in small freestanding buildings, unlike office complexes in some other communities of comparable size. The visual impression of non-residential uses is that of a strongly visitor-dependent economy. The heavily tourism-based economy makes it extremely important that the CCAM relate in detail how issues relating to non-residential uses are analyzed, as standard formulae may not work in such a setting. (2) The Pulse of Visitor Demand and Traffic Functional population is defined in the glossary of the Draft CCAM as “the sum of permanent and temporary populations in the Florida Keys.” Temporary population is further defined as the sum of transient (those people who stay in the Florida Keys for less than 30 days, typically vacationers) and seasonal (those people who stay for 30–180 days). Nothing more is presented in the discussions of population and human infrastructure (hurricane evacuation) about the scale, habits, and demands of the transient population, who may very well be a major

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A Review of the Florida Keys Carrying Capacity Study element in peak demand for infrastructure and services.3 Absolutely nothing in the presentation of the modules relates to day or weekend trippers and their potential impacts on land use, marine environments, or the economy. Observations during a weekend in January (perhaps typical for a peak season) reported heavy traffic along U.S. Route 1 in both directions, including a large presence of sport utility vehicles towing boats of various kinds, many with Florida license plates. Highway turnout areas for parking and shoreline fishing from Key Largo to Key West were filled with vehicles, and even “informal” shoulder parking was crowded. People lined the turnouts, fishing from bridges and sections of the old railroad provided with public access. The impact of these peak period visitors, from solid and liquid waste disposal to part-time jobs for retirees and students, can be quite significant and certainly affects the “carrying capacity” of the Florida Keys. (3) Government Presence in Recreational Attractions and Economy Except for a statement in the Smart Growth scenario that “two additional parks of 5–10 acres each will be developed in the lower Keys,” no information is provided on the significant public presence that generates visits to segments of the Florida Keys and presumably generates jobs for the economic base. Government-managed parks, visitor’s sites, and beaches in the Florida Keys are far from rare. In fact, many such areas are found from Key Largo to Key West, joining commercial recreation and deep-sea fishing as key revenue generators. Indeed, there may be few counties in the United States that have a comparable array of federal, state, and even local attractions along their entire length. These types of areas are not described in the Draft CCAM, and portrayal of government presence is confined to open space and regulation. SCENARIO DESCRIPTIONS Two scenarios are presented in the Draft CCAM report, a ‘Current Conditions’ and a ‘Smart Growth’ scenario. The former is a rough attempt to calibrate the model and the latter represents a future development scenario that poses a modest rate and extent of growth for testing purposes. The Interim Review of the Florida Keys Carrying Capacity Study (National Research Council, 2001) was written with the understanding that different alternatives would be tested prior to final recommendations. It is clear that no conclusions can be drawn about the carrying capacity of the Florida Keys based on the limited testing that has 3   The Miller Consulting Model (2001) for estimating hurricane evacuation clearance time does differentiate tourists from residents. In this model however, the contractor’s use of a linear extrapolation of the clearance times from that model based on total functional population essentially ignores those distinctions.

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A Review of the Florida Keys Carrying Capacity Study occurred, even if the model were suited to this purpose. It would be helpful for the CCAM discussion to include the types of scenario runs that might be included in the final draft. Another troubling issue is the lack of explicit description of the two scenarios that appear in the Draft CCAM Report. Except for the numerical information in Section 4.0 of the Draft CCAM, description of the Current Conditions scenario is confined to a single sentence. While the “Smart Growth” scenario is given considerably more attention, the Scenario Generator only allows the user to specify land use changes. The “Smart Growth” scenario is, therefore, a very simplified representation of all that smart growth is understood to encompass as specified in the National Governor’s Association statement of smart growth principles (National Governors Association, 1999). The Draft CCAM strays far from a document prepared by the URS Corporation in July, 2001 entitled Florida Keys Carrying Capacity Study Scenario Development Guidelines, produced as a follow-up to a workshop with local planners (URS Corporation, Inc., 2001b). The guidelines set out a checklist of items to be covered in any scenario. The document also includes: first, a directive stating “a scenario should be described in words. This description will help both the local planners and the contractor evaluate and determine the option choices in the checklist . . . ,” and second, a sample description of a basic scenario. That description is particularly relevant as an example, because it begins with a paragraph that is not reflected anywhere in the Draft CCAM’s depiction of either scenario. The overall 20-year vision in this Keys-wide scenario is to reinforce a pattern of development articulated as a hierarchy of urban, ‘suburban’ and open space components. Growth will be guided and reallocated into ‘nodes’ or regional centers of urban activity where mixed uses and higher densities are expected to reduce the need for development to grow outward, while decreasing the level of vehicular trips and unit cost for infrastructure (URS Corporation, Inc., 2001b). Although the Current Conditions scenario is not intended to accompany a vision of the future it fails to provide the reader with any text that describes the current pattern of development. Moreover, while the contractor’s January 2 response to the NRC Committee’s questions (Appendix D) included several paragraphs purporting to describe the Smart Growth alternative provided by “local” planners, it did not—with the exception of a single sentence—indicate the principles behind the parameters or why the scenario represented “Smart Growth.” GRAPHIC USER INTERFACE The contractors acknowledge that the Draft CCAM is limited by lack of data on the availability of public infrastructure (other than water supply) for defining the suitability of land for development (Draft CCAM Section 3.1.3). This limita-

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A Review of the Florida Keys Carrying Capacity Study tion influences the manner in which new development is allocated amongst eligible property parcels in setting up alternative future growth scenarios in the Graphic User Interface (GUI). The Draft CCAM also acknowledges (Draft CCAM Section 3.1.3) the presence of errors in the Monroe County Tax Roll zoning data set. This constraint also influences the accuracy with which new development is assigned to different property parcels based on assumptions about zoning constraints. Most modules include built-in constants and coefficients set by the consultant and not amenable to change by the user through the GUI. The user should be afforded the option of altering all such parameters so as to permit both sensitivity analysis and updating of these variables. The committee recommends that options be added to the GUI so that the user can set all parameters, including those currently treated as “built-in constants and coefficients,” (e.g., Draft CCAM Table 3.3, Tables 4.4–4.8, and Table 6.1). According to contractors at URS Corp. (Appendix D), no reliable data could be found on vested developments, which results in an undefined level of uncertainty about the true future population size and corresponding numbers of dwelling units, the numbers of commercial structures and future floor areas, and the resultant impacts of any future growth scenarios analyzed with the model. This uncertainty affects nearly all of the indicators in every model module, although the magnitude of the effects cannot be quantified without some estimate of the number of vested parcels. The “Assumptions & Uncertainties” subsection of the Scenario Generator (Draft CCAM Section 3.13) should clearly identify this uncertainty. URS Corp. should also attempt to obtain a range of estimates of the numbers of vested developments and their resultant residential and commercial land use impacts, and conduct sensitivity analysis of the potential impacts of these ranges. Thresholds are defined for one or more indicator variables for each module of the model (Draft CCAM Appendix C) and constitute the parameters used to indicate the relative acceptability of any future growth scenario analyzed with the model. The definition of thresholds requires value judgments about acceptable levels of the indicator variables, and as currently designed, those value judgments appear to have been made by the consultants.4 In some cases, near-shore ambient water quality for example, thresholds are based on state or federal regulatory standards (Draft CCAM Appendix C, Equation 193). Users may wish to set thresholds differently, even where state or federal standards pertain (e.g., where there may be evidence that certain species or biological communities are negatively affected by conditions less severe than those currently permitted [United 4   Section 3.8 of the Draft CCAM reports that feedback from public meetings was used “to help determine the components of each module, and the end points and criteria used for determining carrying capacity thresholds for quality of life issues.” The Committee’s discussion with the consultants on January 10, 2002, indicated that criteria thresholds were set by the consultant.

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A Review of the Florida Keys Carrying Capacity Study States Environmental Protection Agency, 1999]). Therefore users should be clearly informed about how thresholds are set and should be afforded the option of setting alternative threshold levels. In addition, sources for the thresholds reported in Appendix C of the Draft CCAM should be clearly identified. Users should be provided the opportunity in the GUI to set all threshold levels. Thresholds in the Draft CCAM are misleading and should not be defined where the range of uncertainty in parameter estimates used to calculate indicator variables exceeds the range of variation in the indicator. Output should be limited to indicator estimates, and should be accompanied by uncertainty ranges. The committee also recommends that the user be provided with options through the GUI to select alternative output formats including (1) simple numerical estimates for indicator parameters, and (2) alternative color schemes for numerical or threshold outputs. The suitability assumptions and alternatives for redevelopment scenarios in the Draft CCAM are not explicit. The discussion in the narrative (Draft CCAM, Section 3.1.2) and the information presented in Tables 3.1 and 3.2 do not reflect the range of choices in the GUI and the elaboration provided in response to questions from the NRC committee. The committee recommends that the narrative be revised to more fully document the options available to the user to define redevelopment scenario parameters. In addition, the contractors should explain how development suitability is used in the allocation of new development (Draft CCAM Section 3.1.2) per response to the NRC Committee’s Question #27 (Appendix D), and clarify assumptions used in the scenario selection process per their responses to Questions #94–95, 109–110, 112, and 114–115 (Appendix D). The GUI should be modified to allow for options described in response to the NRC Committee’s Questions #96 and 99 (Appendix D) and do the same for the settings discussed in Questions #97–98 and 100–104 (Appendix D). The Scenario Generator section lacks clear description of the output data format for specific modules of the Draft CCAM, rather only general output data formats are described (Draft CCAM Section 3.1.2). The committee recommends that the text clarify which modules produce land use data at the planning unit level (Socioeconomic, Fiscal, and Potable Water?) and which at the parcel level (Stormwater, Wastewater, and Terrestrial?).