Effective Growth Management - Demonstrating the MCE capabilities of GIS
Summary
The need to make land-use decisions on a national and regional scale in Canada was the impetus for the development of GIS. Roger Tomlinson, the acknowledged father of GIS, led the Agricultural Rehabilitation and Development team that developed what became known as the Canada Geographic Information System. Land use analysis has remained an important GIS application. This article illustrates how criteria reflecting different planning goals can be incorporated into analysis by modifying the parameters of GIS tools in ArcGIS.
GIS allows for multiple criteria evaluation (MCE). This analysis is mainly characterized by allocating weights to assessment criteria for suggesting and ranking alternatives. GIS spatial planning support tools have an important advantage—changing the valuation criteria to visually illustrate and depict the implications of different spatial decisions and alternatives is convenient. The capabilities needed for decision making readily available in a single system make GIS a great tool for integrating in planning processes. This article describes a study that showed how GIS spatial analytical tools can be used to effectively shape decisions that foster urban growth management.
Purpose of the Study
The study identified desirable locations for anticipated low-density residential projects in the Champaign–Urbana region, Illinois. The analysis was based on two almost contradictory approaches and compared the resulting maps.
Map resulting from vector-based analysis showing sites initially identified as suitable for low-density residential development.
The sites were analyzed and evaluated according to two scenarios. The first scenario was based on the developer's point of view and took into account the purchasers' preferences. This scenario considered the developer's preferences pertaining to economic and marketing factors. To that end, the developer was interested in maximizing profit and minimizing the cost of the development and paid little or no attention to environmental concerns.
The second scenario was based on the environmentalists' point of view, which is the opposite of the first scenario. In this scenario, sites were ranked and evaluated on potential for engendering environmentally friendly development. In this regard, protecting the agricultural and forest lands and maintaining the integrity of the environment were the most decisive factors in influencing environmentalists' criteria and decisions.
Factor
Requirements
Location in 100-year floodplain and/or wetland areas
The site must avoid floodplain designated areas or areas that have high runoff rates to prevent any environmental hazards.
Soil type
The site must avoid soils with low bearing strength or poor drainage.
Topography
Avoiding sites that have steep terrains reduces the cost of site grading. Constructing on steep slopes means that a tremendous amount of site grading is necessary for adequate drainage and sewage systems.
Site size
The site should be of a minimum size to increase the overall project profitability.
Site-specific selection factors
Factor
Requirements
Proximity to the existing urbanized areas
The site should be connected to existing residential areas with a high growth potential. This condition ensures that the site is adequately served by the existing facilities and infrastructure. A desirable distance from the nearest built-up areas should not exceed a half mile.
Environmental legislation compliance
To preserve the environmental quality of the area, the site must avoid environmentally sensitive sites and open spaces.
Accessibility
The site must be accessible and well connected by the transportation network to ensure that the commute time required for work, entertainment, or shopping trips does not exceed 30 minutes.
Proximity to industrial and landfill sites
A minimum distance of one mile from landfill and industrial locations and other noxious land uses must be secured to prevent noise and eliminate the immediate threat of chemical emissions harmful to public health.
Airport location
A minimum distance of one mile from the airport, located to the south of the Champaign-Urbana region, was deemed sufficient to avoid adverse impacts of airport noise.
External site selection factors
Site Selection Criteria
The site selection suitability analysis conducted for the study included weighing the different factors in both scenarios and ranking desirable sites. The outcome of both scenarios was evaluated and analyzed based on features of the site and features of the surrounding area.
Analytic Procedures
The analytic steps conducted in this study were combined into two major categories: vector analysis and raster analysis.
Vector-Based Analysis
Using vector-based geoprocessing tools, the final layers were juxtaposed on one map that showed sites initially identified as suitable for low-density residential development. At this stage of the analysis, the output did not reflect either the developer's or the environmentalist's concerns.
Raster-Based Analysis
This analysis considered the two scenarios, introduced in the beginning of the study, that represented a developer's viewpoint and an environmentalist's viewpoint. All layers were classified according to a 10-category color scale for consistency purposes.
Conclusion
The findings from this study were mapped and provided a comparison of the results obtained from both scenarios. Suitable areas for the low-density residential development in the developer's scenario cover a significantly larger portion of the region than the environmentalist's conservative scenario. Because developers typically do not pay a great deal of attention to environmental factors, many more areas were proposed for development. Conversely, environmentalists' efforts to preserve the natural resources of the region greatly limited the amount of land perceived as suitable for future development.
This study provided an example of how GIS could be used to support planning tasks and help make better decisions regarding real-world planning issues and develop communities more effectively. It emphasizes the role of GIS in urban growth management practice and land-use planning decision making. The study argued for the full utilization of GIS in ways that maximize its contribution to the planning practice instead of limiting its application to mapmaking and cartography only.
GIS can deliver insights from data by identifying, displaying, analyzing, and deciphering real-world problems. GIS-based technology provides state-of-the-art analytical and management tools to spatially analyze and study patterns and spatial variations and correlations to make more informed decisions.
