Robustness Criterion for Planning Water Supply/Demand Systems

Water resource systems have been an important part of resources and environment related research at IIASA since its inception. As demands for water increase relative to supply, the intensity and efficiency of water resources management must be developed further. This in turn requires an increase in the degree of detail and sophistication of the analysis, including economic, social and environmental evaluation of water resources development alternatives aided by application of mathematical modeling techniques, to generate inputs for planning, design, and operational decisions. During the year of 1978 it was decided that parallel to the continuation of demand studies, an attempt would be made to integrate the results of our studies on water demands with water supply considerations. This new task was named "Regional Water Management (Task 1, Resources and Environment Area)". This paper is concerned with the robustness of the integrated water supply/water demand systems which is defined as the system ability to perform under different future events than originally expected at a relatively small incremental costs. It is shown how the robustness criterion may be used (in addition to the cost-effectiveness criterion) for screening long lead-time investment alternatives.