Aggregating spatially explicit criteria: avoiding spatial compensation

Abstract

Since the shift from safety-oriented planning towards risk-based flood management planning, both hydrology/hydraulic research as well as operations research have made remarkable progress. Unfortunately, in the transfer of information between both areas of expertise, valuable spatial information is being lost, which may lead to flawed decision-making. Spatial aggregation of positive or negative criteria score across cells as is customary holds a major pitfall: spatial compensation at the river basin scale. If one cell's benefits outweigh another cell's detriments, these detriments are lost in the spatial aggregation process. However, not all variables are commensurable. A decision-maker might reasonably object to an alternative that generates additional damage, even if they are amply compensated elsewhere. Current aggregation procedures have more of a tendency to veil these problems then to deal with them. Moreover, valuable information defined as spatial equity is also often lost in the decision matrix. In this paper, classical criteria are changed and new criteria are selected to inhibit the abundant spatial compensation, add the variable of spatial equity and provide decision-makers with non-ensconced and therefore more accurate results. The shortcomings and error-proneness of the established frugal summation procedures are outlined by intuitive simplified examples. These examples also serve to illustrate and test the logical performance of the proposed methodology. To test their applicability, they are used in an actual test case, selected for the problem's intricacy.

Keywords:

• Spatial compensation
• spatial equity
• flood management

Acknowledgements

Data from the Ministry of Agriculture, Nature Conservation and the Environment of Thuringia (TMLNU) and the Ministry of Agriculture and Environment of Saxony-Anhalt (MLULSA) are gratefully acknowledged. The authors are also indebted to two anonymous referees for their valuable suggestions.

Funding

Funding for this work was provided by the German Ministry for Education and Research (BMBF) [grant number 02WH0588].