Multicriteria Analysis under Uncertainty with IANUS—Method and Empirical Results

Integrated assessment of decisions under uncertainty for sustainable development (IANUS) is a method for aiding public decisionmaking that supports efforts towards sustainable development and has a wide range of applications. We introduce the main features of IANUS and illustrate the method by using the results of a case study in the Torgau region (eastern Germany) with conflicts over economic development and groundwater protection in the Elbe River basin. IANUS structures the decision process into four steps: scenario derivation, criteria selection, modelling, and evaluation. Its overall aim is to support the finding of policy solutions in a participatory setting and to extract the information needed for a sound, responsible decision in a clear, transparent manner. The method is designed for use in conflict situations where environmental and socioeconomic effects need to be considered and so an interdisciplinary approach is required. Special emphasis is placed on a broad perception and consideration of uncertainty. Three types of uncertainty are explicitly taken into account by IANUS: development uncertainty (uncertainty about the social, economic and other developments that affect the consequences of decision), model uncertainty (uncertainty associated with the prediction of the effects of decisions), and weight uncertainty (uncertainty about the appropriate weighting of the criteria). The backbone of IANUS is a multicriteria method with the ability to process uncertain information. In the case study the multicriteria method PROMETHEE is used. As PROMETHEE in its basic versions is not able to process uncertain information an extension of this method is developed here and described in detail. One methodological lesson to be learned from the experience of the case study reads that the design of the participation process must be planned and executed carefully to prevent important stakeholders backing out of the participatory evaluation process—as happened with the decisionmakers in the Torgau case study.