Envisioning sustainability of urban water systems through the lens of Circular-One-Water-Approach: modelling and analysis using Fuzzy Cognitive Maps

Increasing pressures from water scarcity, urbanization, aging infrastructure, and climate change require sustainable management strategies for Urban Water Systems (UWS). Nevertheless, existing sustainability assessment methods often disregard the causal interactions among indicators, limiting their ability to represent system complexity and support decision-making. This study proposes a novel sustainability assessment framework that integrates the Circular Economy and One Water Approach (COWA) using Fuzzy Cognitive Maps (FCMs). By identifying and quantifying causal relationships, the proposed FCM can capture system-wide feedback mechanisms. Four water management paradigms were evaluated (Business-as-Usual, Circular Economy, One Water, and COWA), with results indicating that COWA can improve sustainability in 30%. Specifically, the FCM analysis shows that environmental protection and resource recovery have the highest priority for sustainability (26-47%), followed by stakeholder engagement and human health (17–34%). These findings highlight the importance of integrated strategies that enhance stakeholder engagement, reduce pollution, and promote circularity in UWS management.