Evaluation of water supply augmentation and water demand management options for the City of Cape Town

This paper discusses an application of MCDA to integrated water resource planning for the City of Cape Town. As a result of rapid growth in recent years, there have been increasing pressures on limited water resources, leading by the end of 2000 to severe restrictions having to be imposed on consumers. Planners needed thus to develop and to evaluate options both for water supply augmentation and for water demand management. The role of structuring these problems in MCDA terms, in order to facilitate a common understanding between a number of interest groups, is first discussed. Thereafter, the use of simple multiattribute value functions to score the various supply and demand management options in a group setting is described. One advantage of this approach was that when additional alternatives were proposed at a later date, their evaluation could easily be incorporated with the earlier results. The intention during this study was to identify high priority interventions (which may need to be implemented quickly), as well as options that are probably not worth implementing in the short term. It is recognized that at a later stage, the high priority items may need to be ‘packaged’ into a number of alternative policy scenarios, which will be evaluated in more holistic terms. At the time of writing, the results of the analysis described here had been presented as a single proposal to the city council, and have led to more detailed design studies for implementation.