A Fuzzy TOPSIS model Framework for Ranking Sustainable Water Supply Alternatives

Recently water supply alternative sources, recognized as sustainable and ecofriendly have become popular. This is consequent on the scarcity and increasing demand for water, especially by developing nations characterized by industrialization and increasing population growth. However, the intricacies and overwhelming nature of factors to be considered in reaching a decision on a best alternative has further prompted the emergence of several decision support tools, some of which arouse discrepancies with setbacks. We employ here, the uniqueness of fuzzy TOPSIS (technique for order preference by similarity to ideal solution), a multi‐criteria decision approach (MCDA), to aid in deciding the most preferred alternative water supply among, desalination, water borehole, rain water harvesting, reclaimed water, black water, grey water and water importation. This method is reckoned for its ease in handling both quantitative and qualitative data. Moreover it also overcomes the uncertainties in expert opinions usually encountered in the decision process due to the numerous variables, criteria and attributes that interplay in achieving sustainability. Results from analysis on data aggregation, normalization and performance ratings, coupled with the weighted distance from the positive and negative ideal solutions indicated that borehole ranked topmost followed by rain water harvesting (RWH). These revelations are apt to all stakeholders in the water delivery sector and in deliberations on the paradigm shift to water conservation and management measure.