Spatial patterns of water security risks in the deglaciating Andes

Deglaciation alters hydrological processes in mountain catchments by modifying runoff regimes, impacting water quality, availability, and storage, with widespread consequences for downstream water security. While the timing and rate of glacier loss are increasingly well constrained, how glacier retreat translates into spatially heterogeneous water security risk remains poorly understood. In water-scarce catchments, small reductions in glacier melt may have severe impacts, whereas in water-abundant systems, large losses may be inconsequential. Risks can also differ substantially between upstream and downstream regions due to spatial heterogeneities in hazards, and the exposure and vulnerabilities of social-ecological systems.

To address this gap, we present a conceptual and quantitative framework to assess deglaciation-driven water security risk in Andean catchments, grounded in a comprehensive risk assessment approach (risk = hazard × exposure × vulnerability). First results quantify the effects of glacier retreat on the hazard and exposure components using high-resolution hydrological simulations from the JULES land surface model. The analysis spans ten glaciated river basins across the Andes, covering a broad climatic gradient from hyper-arid to humid conditions. A key novelty is our spatially explicit approach, accounting for upstream-downstream heterogeneities in hazard and exposure quantifications.

Our framework moves beyond glacier-centric assessments by explicitly linking cryospheric change to downstream water security risk across diverse hydro-climatic settings. By providing a transferable but region-specific method, our approach offers a foundation for identifying hotspots of emerging water security risk under continued glacier retreat.