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OPEN SPACE MAPS
The challenge of open-space planning lies not only in identifying useful management tools at the local level but also in distinguishing what is open space. Chapter Two describes the process by which citizens identified open-space themes that the community believes are important. To review, these themes are:
This Chapter explains how maps were created to reflect these themes. I.MAPPING OF OPEN-SPACE RESOURCESMaps are graphic illustrations of geographic information. For instance, using a road map one can determine the distance from Riner to Blacksburg. The maps created for the Open-Space Initiative show where important open-space resources are located within the County and the Town. Open-space resources are defined as the natural, historic, and cultural features present in the County and the Town. Table 4.1 lists the resources depicted in the Open-Space Maps.
These resources are physical features that, when illustrated on the Open-Space Maps, also reflect open-space themes, which are conceptual. OPEN-SPACE RESOURCESIn order to address how natural, cultural, historic, and recreational resources interrelate with one another and how they should best be planned, maps of these resources must be created at a scale and accuracy usable by landowners, land-planning consultants, County and Town planners, and interested resource-conservation organizations. The twelve open-space resources compiled as part of the Initiative reflect:
Most of the twelve open-space resources represent open-space features found throughout the Commonwealth (historic sites), while several are more characteristic of Montgomery County (karst features such as caves and sinkholes). Table 4.2 summarizes the twelve resources and explains why each is an open-space resource. Throughout the United States, the United States Geological Survey (U.S.G.S.) is recognized as the lead agency for geographic mapping. Almost every map the average citizen sees or works with relies in part on mapping prepared by the U.S.G.S. The Open-Space Maps are no exception. Much of the data compiled for the project was drawn from U.S.G.S. mapping and was printed at a scale of 1":2,000'. At this scale, the Virginia Tech drill field is approximately three-quarters of an inch in length. Data from sources that were not prepared at this scale were enlarged or reduced as necessary. The scale is appropriate for the Open-Space Initiative; however, the information shown on the Open-Space Maps will have to be supplemented by site-specific mapping and actual field research when it is applied to a particular piece of property. Printing the maps for presentation and distribution will require using larger scales such as 1":5,280'. Each of the twelve open-space resources is maintained as a separate layer in a digital file system used to compile the Open-Space Maps. Each layer can be rendered visible or hidden, shown in different colors, and edited independently from the other layers. Each layer acts as a piece of transparent "tracing paper," so that other layers of "tracing paper" are visible, but it can be removed, shaded, or edited without affecting the information on the other layers.
SAMPLE AREAS SHOWING THE DATA LAYERSTo provide the reader with a visual example of resource layers, a sample region was chosen that exemplifies a great diversity of open-space resources and includes a portion of both Blacksburg and Montgomery County. This sample is the Blacksburg quadrangle, with particular focus on the area surrounding Prices Fork Road, which includes the interchange with U.S. 460. The area contains a wide diversity of natural, cultural, and recreational resources. Figures 4.1 through 4.3 depict the resource-data layers collected for this planning process. The focus area is a twelve-square-mile area within which are found:
II.ILLUSTRATING OPEN-SPACE THEMESThe Open-Space Maps not only illustrate the resources, but also organize the resources to depict the themes established at the community-involvement meetings. With these maps two objectives are achieved:
The Open-Space Initiative met these objectives by developing four presentation maps that will be available to the general public at area libraries and Town and County offices. The four maps are the:
The Natural-Resources Map illustrates the physical open-space environment. Below are a selected set of themes reflected on this map.
Each of these open-space themes can be clearly linked to the physical environment (soils, karst features, rivers, and ecosystems among others) or an identified physical resource. The variety of water resources illustrated include not only flowing waters but also waters protected by federal law (wetlands) and waters of particular public-health concern (public water supplies). Historic resources are shown as a component of the physical environment in this map. Historic sites and districts with National Register status are illustrated. Many archeological sites, older structures without official designation, and burial sites exist within the County and the Town. Unfortunately these sites have not been designated through a formal process with input from historians and the public. Therefore, only officially-recognized historic districts and sites are illustrated on the Natural-Resources Map. LANDS-UNDER-SPECIAL-STATUS MAPThe second map, Lands-Under-Special-Status, focuses on two open-space-resource layers representing existing local government programs that protect agricultural and forest lands. This map also illustrates lands owned by the public or nonprofit organizations, indicating where public and private investment is being used to conserve open space.
Properties being taxed under the land-use-assessment program and properties located within Agricultural and Forestal Districts represent agricultural and forested areas that are active farms or managed for forest resources. Both the land-use-assessment and agricultural-and-forestal-district mechanisms are discussed in Chapters Three and Five. The Lands-Under-Special-Status Map shows the locations of these lands in the Town and County, allowing a comparison of these areas to the physical features illustrated in the Natural-Resources Map. The locations identified in the Lands-Under-Special-Status Map represent properties where the owners have made a commitment to active agricultural and forest management. In some instances land with high natural-resource value is owned by the public or a nonprofit organization to preserve this value. Both commitment to active agriculture and preservation of natural areas are central to responding to the open-space themes established through the process of community involvement.
The project team conducted a limited viewshed analysis. Viewshed analysis identifies scenes or landscapes that are picturesque and shape the viewer's perception of "place." Places of significant scenic value include views of prominent mountains, natural views from major roads, landscapes surrounding historic buildings, and stream corridors. The analysis demonstrated that scenic viewsheds are a tremendously difficult open-space resource to map in a comprehensive way. The identification of scenic views not only relies on the general landscape but also involves site-specific conditions. This analysis reaffirmed the citizens' conviction about the scenic resources in the Town and the County. In fact, the analysis identified so much of the Town and County as being scenic that the emphasis of the Visual-Resources Map had to be changed from critical views to critical viewpoints.
The Visual-Resources Map identifies scenic corridors (primarily public roads and public facilities) from which views are readily observed. Views from these vantage points are:
The Natural-Resources, Lands-Under-Special-Status, and Visual-Resources Maps form the backdrop of open-space themes, which will serve as a significant asset for planning staff and landowners. RESOURCE-OVERLAY MAPThe Natural-Resources, Lands-Under-Special-Status, and Visual-Resources Maps illustrate open-space resources within the County and the Town. These Maps allow landowners and planning staff to identify the many different resources in the County and Town. The Resource-Overlay Map looks at the location of open-space resources from another perspective. This Map answers the question, where are open-space resources the most concentrated? The Resource-Overlay Map was made by stacking individual resource layers one on top of another. Seven open-space-resource layers were used in this stacking process: wetlands (including a buffer area), prime soils, critical habitat, one-hundred-year floodplains, public water supplies (waterworks), karst features (including caves, sinkholes, and generalized areas of high sinkhole density), and historic sites (including districts). Streams and rivers were shown on the map, but were not used in the stacking process. The resulting compilation is the Resource-Overlay Map, which illustrates the number of resource layers present at any one place in the County and the Town. Thus the Map shows the relative number of resources present in a given area by the darkness of the color on the Map in that area (the darker the color the more resources present) or by the density of the hatch pattern (denser patterns reflect more resources being present). The Resource-Overlay Map shows as many as four resources present in one location. When using the Resource-Overlay Map one should consider the density of open-space resources as a spectrum. Where a high intensity of resources is present, the ease of development is generally low due to physical and legal constraints. Areas of high resource intensity may be best managed as farmland, forest, or natural habitat.
Even though an area high in resource concentration calls for special consideration, sometimes areas with low density are as important Ñ if not more so Ñ because of the nature of the resource(s) (endangered-species habitat). This approach represents a guide for the Town and County in establishing priorities for the protection of open space, and in weighing the long-term impacts of land-use planning. The Resource-Overlay Map clearly illustrates that areas identified as being dense in open-space resources are also very vulnerable. These areas tend to be stream valleys and areas of karst geology. Such sites are frequently found in existing corridors of urban development, particularly the Prices Fork, Mount Tabor, and Childress areas. III.INTEGRATING OPEN SPACE INTO THE DEVELOPMENT PROCESS
Today, landowners file subdivision plats, apply for rezonings, and present site plans to the Town or the County as a component of the development process. Town and County activities are preceded by environmental reviews. These already require the identification of streams, burial sites, floodways, and other important site constraints. These processes have been institutionalized because they serve two functions: (1) platting and site plans provide a mechanism for ensuring compliance with local standards such as setbacks, lot size, and road design; (2) more importantly, these procedures encourage landowners and the Town or County to think through development projects before they invest significant amounts of capital. Local government is simply advising landowners, as well as itself, to "look before you leap." The Open-Space Maps build upon this existing role of local government. The mapping described above is presented at a large scale. Its role for both planning staff and developers is to indicate the potential for natural-resource conflicts on a specific development site. This is an important function that, in a limited way, exists today in the form of environmental-impact statements, bank-lending requirements, and the public-hearing processes associated with land acquisition and development. None of these current practices is comprehensive, nor do they allow a strategic prioritization of open-space resources. Identification and prioritization of open-space resources in a particular development project are complicated by the fact that, whereas natural features do not respect property lines, boundaries are fundamental to the development process. To address the shortcomings of today's development process and to overcome property-boundary issues, the open-space resources have been organized into a single digital map. With computer-aided cartography the open-space-resource layers have been "fit" to the existing tax-parcel map of the County. This tax-parcel map was developed using Montgomery County's E-911 digital mapping and the County's parcel maps. Computer-aided cartography makes the identification of resources on a particular tax parcel simpler and quicker than would be possible with a manual map system. Using a personal-computer-based mapping program significantly reduces the cost both of map editing and preparation of property-specific maps for landowners making such a request. Because of data limitations the Open-Space Maps cannot reasonably be treated as absolute. The maps are only as good as the data used to compile them, and some of the data used are too general to be applied to individual development activities. But by identifying the potential presence of open-space resources, the Town/County staff and the landowner can pursue site-specific data essential to managing the open-space resources that are confirmed to be actually present. If the Open-Space Maps indicate the potential presence of open-space resources, the first step in the development process should be to ascertain their actual existence and precise location. A developer knowing the location of resources can better manage site preparation and site design to minimize impact on these resources and utilize them in the marketing of the final design.
©Montgomery County Department of Planning
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1992
Montgomery County
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