Map transformation and aggregation methods for spatial decision support

Abstract

The performance of policy alternatives for environmental management is often represented in maps. These maps are used to compare alternatives and ultimately to select the one preferred. Since most people use reference maps in everyday life, such as road maps or town maps, they are familiar with them and consider them as an appropriate decision support instrument. In practice effective use of maps is a difficult task for many people. Spatial evaluation methods are designed to support this task. Spatial evaluation methods help the decision maker by structuring and simplifying the map representations of the alternatives. This can be done by transformation or aggregation of the information presented in a map. In transformation, maps are transformed or combined in such a way that only the information relevant to the decision is presented. For aggregation, indices are defined that represent certain aggregate features of the map that are relevant to the decision. Spatial evaluation methods presented in this chapter are developed to support the comparison of mapped policy alternatives for the Green Heart of the Netherlands. Seven examples of policy questions are used to illustrate the use of spatial evaluation methods. It is shown that the use of these methods increases understanding of the differences between the alternatives. The spatial evaluation methods used do not provide the decision maker with a single answer, such as which alternative is the best, but result in a series of answers depending on the specific questions asked. All methods are included in a small software package that invites decision makers to use the methods to experiment with their problem.