Benjamín Sotomayor González

This study investigates the paradoxical water security challenges in western Chilean Patagonia, where the regional abundance of water resources masks significant vulnerabilities of drinking water systems. We conducted an integrated socio-hydrological analysis over rural (APR) and urban (APU) drinking water systems, which provide water to approximately 846,000 people. We georeferenced 343 drinking water intake points, from which 51.6% are sourced from groundwater, and 45.8% from surface waters (2.6% other sources). An eco-hydrological characterization was conducted on the 147 watersheds supplying water to the surface intake points. Watersheds were characterized by their main hydrological, morphological, and land cover features, as well as by their level of anthropization (AI) and water stress index (WSI). Social dimensions were captured through structured interviews with 117 APR directorate leaders regarding their perceptions of infrastructure, governance, climate change, and local water management challenges. Our findings suggest that water availability in Patagonia creates a mirage of water security. AI and WSI indicate high variability in the status of water sources, with 25% of watersheds showing high levels of anthropization and 33% with medium to high levels of water stress, making it relevant to explore the results through a combination of hydroclimatic, longitudinal, and latitudinal gradients. A novel analysis linking WSI and AI to governance perceptions was conducted, finding significant inverse correlations between WSI and both technical capacity and users’ participation. Despite the region’s evident abundance of water resources, rural communities consistently express concerns regarding supply sustainability, infrastructure deficiencies, insufficient technical support, and climate change risks to current and future water availability, all of which constrain water security in Chilean Patagonia.

The first-ever field measurements conducted at the outlet glaciers Gualas and Reichert at the Northern Patagonian Ice Sheet, Chile, provide the basis for this work. Both glaciers currently terminate in large (2 km resp. 9 km length) proglacial lakes. The glaciers have retreated rapidly over the past four decades, whereby Reichert glacier retreated by over 100 m per year. Our bathymetry measurements of these lakes make it possible to estimate the mass loss and make assumptions about floatation of these glaciers during retreat. The lakes have depths of up to 250 resp. 350 m and therefore the volume previously occupied by the glaciers is significant. Recent UAV surveys of the final 3 km of the tongue of both glaciers and satellite data provide high-resolution elevation models and are employed to estimate mass loss since the 2000s. With this preliminary study we aim to investigate whether mass loss of these glaciers has been underestimated due to neglected subaqueous ice mass loss. Knowledge from this study will contribute to improving past, present and future mass change estimates of similar glaciers, with relevance for, e.g., sea level rise contribution from ice sheets and their outlet glaciers.