Technical and economic potential of rainwater harvesting systems in semi-arid urban areas: Multicriteria diagnosis for comprehensive evaluation and optimization.

Water scarcity in urban areas of the Global South remains a major challenge. While rainwater harvesting systems (RWHS) are promoted, they often ignore complex hydrological, demographic, and urban interactions. This article explores the question: How to comprehensively assess the technical and economic viability of RWHS, considering housing types, consumption patterns, and variable rainfall, in urban settlements of the Global South? This study presents indicators for diagnosing and assessing the technical and economic efficiency of the RHWS. Six scenarios were analyzed by combining different rainfall types and RWHS to identify optimal options. In this multicriteria analysis, a PSO was employed, complemented by AHP, CRITIC, and TOPSIS methodologies to facilitate a more comprehensive and formal evaluation of the criteria. The diagnosis identified effective solutions within limited harvesting areas and constrained periods, though these solutions exhibit high sensitivity to minor parameter variations. This underscores the necessity for a more thorough analysis to enhance the resilience of these solutions and to address water scarcity issues across the Global South, including Mexico.