Identifying Water Stress Hotspots in Chilean Patagonia Using Spatially Explicit Water Yield Modeling and Anthropization Proxies

Despite the widespread perception of Chilean Patagonia as water-abundant, the region exhibits marked climatic and landscape heterogeneity. This study evaluates relative water availability across Coyhaique Province (12,712 km2), where projections indicate a trend toward warmer and drier conditions. The province has a marked west–east gradient: humid valleys in the west contrast with much drier areas to the east, where most of the population and development are concentrated. To identify water stress hotspots, we combine spatially explicit water yield estimates derived from the InVEST Seasonal Water Yield model with an anthropization index used as a proxy for water demand, constructing a relative Water Stress Index. The results indicate that water stress increases toward the east, driven by the combined influence of climate variables and anthropogenic pressure. These results indicate that the characterization of Patagonia as uniformly water-rich does not hold at the provincial scale, and highlight the limitations of coarse regional assessments in capturing intra-regional hydrological heterogeneity. The spatial pattern of water stress revealed here exposes a mismatch between the resolution at which hydrological heterogeneity operates and the scale at which prevailing water governance frameworks are formulated, underscoring the need for bottom-up, fine-resolution diagnostics that incorporate local hydrological variability into water planning and governance. The province-scale analysis presented here provides a representative case study for Aysén and illustrates the broader relevance of spatially explicit diagnostics in contexts where regional indicators mask local water stress. Strengthening monitoring networks, protecting headwater catchments, and promoting a decentralized approach to water management remain essential to reduce the risk of human-driven water scarcity.