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Comparative Advantage and Spatial Interactions: Implications for GIS-Based Land Allocation Analysis
ABSTRACT
Numerous researchers have used GIS to solve land allocation problems using what is basically a comparative advantage process (CAP). Suitability maps are constructed showing the "production potential" of a variety of alternative "products" that could be produced from each region in a map. Thus, a suitability map describing the grazing potential of an area might show that a region with good soils and adequate rainfall can support a great deal of grazing, while an area with poor soils and/or little rainfall has a limited ability to support grazing. The basic CAP approach requires the researcher to develop one such suitability map for each possible land use under consideration. Once these suitability maps are created, each map is multiplied by the "value" of the product it represents (e.g., the grazing map would be multiplied by the unit value of grazing, a timber map would be multiplied by the unit value of timber, etc.) to produce a series of value maps. The values in these value maps are compared to one another, and each region is assigned to the land use that maximizes the value of its products. There are many difficulties in implementing this approach, including the fact that many of the "products" and "values" involved in this process concern nonmarket goods (e.g., open space), which makes production of suitability maps and derivation of unit values very difficult. The simple process just described also ignores spatial iterations between regions. Thus, while it is logical to assume that a timber harvest area adjacent to a wildlife habitat zone might impact the wildlife zone, the simple process just described ignores any such interactions. In this study, a modified version of the land allocation process just described is presented. It will be demonstrated that modified approach, which relies on goal programming techniques, can address the issue of spatial interactions between land uses. |