Ranking water-scarcity management strategies using the TOPSIS method

Water scarcity is intensifying due to climate variability, population growth, and declining freshwater quality, creating an urgent need for transparent and systematic approaches to prioritize water management strategies. This study applies the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), a multi-criteria decision-making (MCDM) method, to evaluate three water-scarcity interventions: rainwater harvesting (A1), water recycling and reuse (A2), and desalination (A3). Evaluation inputs were obtained through a structured assessment involving 50 water-sector experts, who rated the importance of criteria and assigned performance scores for each alternative. Five evaluation criteria: water efficiency, cost-effectiveness, environmental impact, social equity, and technological feasibility, were considered and weighted according to expert assessments. A decision matrix was constructed, normalized, and weighted, and the positive-ideal and negative-ideal solutions were determined to calculate separation measures and relative closeness coefficients. The results indicate that rainwater harvesting (A1) achieves the highest relative closeness to the ideal solution (\: C₈=0. 489), followed by water recycling and reuse (A2) (\: C₈=0. 471), while desalination (A3) ranks third (\: C₈=0. 467). These findings suggest that rainwater harvesting provides the most balanced performance across the selected sustainability criteria within the evaluated framework. The proposed TOPSIS-based framework offers a transparent and adaptable tool for supporting water management decision-making and can be further enhanced by incorporating region-specific datasets, additional alternatives, and sensitivity analysis to improve robustness.