Hybrid Glacio‐Hydrological Modeling Reveals Contrasting Runoff Changes in Western Patagonia Over the 21st Century

Climate change poses a serious risk for the freshwater ecosystem of Western Patagonia and threatens glacial and non-glacial water resources. Here, we model the historical glacio-hydrology of 2,236 catchments across the Western Patagonia, and project climate change impacts through the 21st century. To this end, we develop a novel modeling framework that combines Long Short-Term Memory (LSTM) neural networks with ice-dynamical glacier modeling using the Open Global Glacier Model (OGGM). We evaluate the ability of this hybrid framework to predict streamflow in ungauged basins (PUB) and regions (PUR) through 10-fold cross-validation and compare the results with those obtained with a LSTM model without a glacier component, and two process-based coupled glacio-hydrological models. The hybrid modeling approach outperforms all other approaches in 38% and 44% of the catchments considering PUB and PUR evaluations, respectively. Using our new hybrid approach, we estimate an average regional freshwater flux of 19,815 m3 s−1 for the period 2000–2019, with glacier melt contributing 29% during the summer season. Under a high-emission scenario (Shared socioeconomic pathways 5-8.5), the northern region (>46°S) is projected to experience the largest reductions in runoff, with dry season runoff decreasing by almost 50% by the end of the century. In contrast, runoff increases are projected for glacierized basins in the southern regions, with average relative changes of 10%–25% and a marked seasonality shift. The results highlight the potential of hybrid modeling in glacio-hydrology and provide important information for climate change adaptation in Western Patagonia.