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Abstract. The Heihe River basin in northwest China depends heavilyon both anthropogenic and natural storage (e.g., surface reservoirs, rivers andgroundwater) to support economic and environmental functions. The QilianMountain cryosphere in the upper basin is integral to recharging thesestorage supplies. It is well established that climate warming is drivingmajor shifts in high-elevation water storage through loss of glaciers andpermafrost. However, the impacts on groundwater–surface-water interactionsand water supply in corresponding lower reaches are less clear. We built anintegrated hydrologic model of the middle basin, where most water usageoccurs, in order to explore the hydrologic response to the changingcryosphere. We simulate the watershed response to loss of glaciers (glacier scenario),advanced permafrost degradation (permafrost scenario), both of these changes simultaneously (combined scenario) andprojected temperature increases in the middle basin (warming scenario) by alteringstreamflow inputs to the model to represent cryosphere-melting processes, aswell as by increasing the temperature of the climate forcing data. Netlosses to groundwater storage in the glacier scenario and net gains in the permafrost and combined scenarios showthe potential of groundwater exchanges to mediate streamflow shifts. Theresult of the combined scenario also shows that permafrost degradation has more of animpact on the system than glacial loss. Seasonal differences ingroundwater–surface-water partitioning are also evident. The glacier scenario hasthe highest fraction of groundwater in terms of streamflow in early spring. Thepermafrost and combined scenarios meanwhile have the highest fraction of streamflowinfiltration in late spring and summer. The warming scenario raises the temperatureof the combined scenario by 2 ∘C. This results in net groundwater storageloss, a reversal from the combined scenario. Large seasonal changes inevapotranspiration and stream network connectivity relative to the combined scenario show thepotential for warming to overpower changes resulting from streamflow. Ourresults demonstrate the importance of understanding the entire system ofgroundwater–surface-water exchanges to assess water resources underchanging climatic conditions. Ultimately, this analysis can be used toexamine the cascading impact of climate change in the cryosphere on theresilience of water resources in arid basins downstream of mountain rangesglobally.