Localized buffering, widespread decoupling: Glacier meltwater's shrinking influence on high-Andean wetland hydrology

High-altitude wetlands are vital for water storage, flow regulation, and biodiversity in mountain regions. Their hydrologic resilience depends on water inputs from precipitation, groundwater, snow, and glacier melt, making them sensitive indicators of climate-induced hydrological change.  However, the specific impacts of rapid glacier retreat and shifting precipitation regimes on the spatiotemporal stability of these ecosystems remain poorly quantified, limiting the development of targeted adaptation strategies.

This study investigates the hydrological drivers and spatial dynamics of high-altitude wetlands in two Peruvian Andean catchments: glaciated Cordillera Vilcanota and nearly deglaciated La Raya. Using high-resolution satellite-based wetland mapping (2019-2025), we employ a sub-catchment-based regression analysis to disentangle the role of precipitation and glacier melt in controlling wetland seasonal and interannual variability.

Our results show that seasonal wetland dynamics are primarily driven by precipitation, which explains up to 25% of wetland variability. However, in proximity to glaciers, wetland seasonality is significantly dampened, indicating a stabilizing effect of glacier meltwater inputs. Spatially explicit analysis reveals that this glacier-buffering effect is highly localized: it attenuates sharply with distance from periglacial and becomes statistically undetectable beyond approximately 12 km. This suggests that most high-Andean wetlands are hydrologically decoupled from direct glacier melt influence, and their future vulnerability will be predominantly governed by precipitation changes.

This work provides a novel spatially explicit assessment of glacier–wetland hydrological connectivity, which is a key and understudies component of mountain water cycles. The findings advance the understanding of how different water resources regulate wetland variability and offer a monitoring framework that can support the development of adaptation strategies for sustaining mountain ecosystem services under climate change.