Abstract

Water security is a key objective for advancing sustainable development and is becoming increasingly difficult to achieve under the pressures of climate change. Ensuring water security requires equitable access to water services of adequate quantity and quality to meet diverse needs, while also guaranteeing the sustainability of these services in the face of natural and anthropogenic threats. The concept of territorial water vulnerability is introduced as the propensity of a given territory to fail in adequately meeting water needs due to its structural susceptibility to socio-environmental stressors. The Territorial Water Vulnerability framework is applied to assess water security risks related to urban drinking water services in the Gran Valparaíso conurbation in Chile, a territory affected by a decade-long drought, pronounced social inequalities, and fragmented water governance. Using a fuzzy logic approach, an integrative index is developed that combines territorial indicators of sensitivity and response capacity, considering both technical and sociocultural factors driving household vulnerability to water scarcity at a fine spatial resolution. Through cluster analysis, neighbourhood profiles with common characteristics accounting for elevated vulnerability levels are identified. The results show that 4,841 out of 10,042 census blocks exceed a vulnerability threshold of 0.5, primarily due to sensitivity factors such as water supply constraints, coverage of informal settlements, and frequency of unscheduled annual outages, compounded by a consistently low response capacity (median 0.08 on a scale from 0 to 1). This research provides: (1) an analytical framework to assess urban water security from a household-level perspective that incorporates social dimensions; (2) a methodological approach for high-resolution vulnerability analysis that integrates technical and sociocultural systems; and (3) empirical evidence to inform public policy in a region where water security has been underexplored.