An increasing number of water resources problems have been formulated in a multiobjective fashion. Due to the conceptual difficulties involved in using multiobjective models for the first time (i.e., selecting criteria, specifying satisficing values, and evaluating trade-offs), several researchers have developed multiobjective decision support tools which meet two of the three requirements of a DSS. Namely, these tools provide analysis and interpretation capabilities, but not necessarily information management capabilities. Nonetheless, the potential of these tools in a fully developed DSS has become well known.
Recent examples of multiobjective decision support in water resources include Bogardi and Duckstein [1992], who presented an interactive multiobjective analysis method to embed the decision maker's implicit preference function; Ridgley and Rijsberman [1992], who employed multicriteria decision aid for a policy analysis of a Rhine estuary; and Theissen and Loucks [1992], who presented an interactive water resources negotiation support system. In the last two examples, the authors concluded that the use of multicriteria evaluation effectively provided a group DSS for the analysis.
Other work has focused on integrating technologies to support the multiobjective analysis. Simonovic et al. [1992] presented a rule-based expert system to facilitate and improve the choice of multiobjective programming weights to be used in a reservoir operation model. Short- and long-term operating goals represented the trade-offs in the model. Lee et al. [1991] developed a DSS for dredge-fill management based on a modified fuzzy-composite programming method for multiobjective problems under uncertainty. Values of risk and cost were transformed into fuzzy numbers to incorporate uncertainties into the trade-off analysis.