Employing a fully distributed hydrological model of SPHY (spatial processes in hydrology), we assessed the future water availability from a highly glacierized basin of Hunza in the western Karakoram under plausible climates as projected by the representative concentration pathways (RCPs). We successfully calibrate and validate the SPHY model for the periods 1994–1997 and 1997–2000 respectively using three high-altitude representative meteorological stations from the Water and Power Development Authority (WAPDA), Pakistan. Then, we run the model for near- (2007–2036), mid- (2037–2066), and far-future (2067–2096) climate projections under three different RCP scenario, i.e., RCP2.6, RCP4.5, and RCP8.5. Each scenario includes four high-resolution (~ 50 km) climate experiments that are obtained from dynamically downscaling the Coupled Model Inter-comparison Project Phase 5 (CMIP5) experiments under the framework of the Coordinated Regional Climate Downscaling Experiments (CORDEX) for South Asia. The SPHY model projects a substantial increase in the ensemble mean discharges throughout the 21st century under all RCP scenarios. Such an increase is dominated by the enhanced glacier melt contribution under the high warming scenario of RCP8.5. Besides featuring a declining trend, snowmelt contribution will also remain higher than that of the historical period throughout the 21st century and under all RCPs. Our flow duration curve analysis suggests that high and median flows are projected to increase while low flows are projected to decrease in the future. These findings provide invaluable insights into the uncertainty spectrum of the water availability from the western Karakoram across envisaged future climates, which will be supportive in better managing the downstream water resources.

通过使用SPHY的完全分布式水文模型（水文学中的空间过程），我们评估了喀喇昆仑山脉西部高冰河盆地在有代表性的集中路径（RCP）预测的合理气候下未来的可用水量。我们分别使用来自巴基斯坦水利和电力发展局（WAPDA）的三个高空代表性气象站分别成功地校准和验证了1994-1997年和1997-2000年的SPHY模型。然后，我们针对三种不同的RCP情景，即RCP2.6，RCP4.5，在（2007-2036），中期（2037-2066）和远期（2067-2096）的气候预测中运行该模型。和RCP8.5。每个方案都包含四个高分辨率（约50 km）气候实验，这些实验是通过在南亚区域气候减缩协调实验（CORDEX）的框架下，对耦合模型间比较项目的第5阶段耦合模型（CMIP5）实验进行动态缩减而获得的。在所有RCP方案下，SPHY模型预测了整个21世纪整体平均排放量的大幅增加。在RCP8.5的高变暖情景下，这种增加主要是由冰川融化作用的增强所决定的。除了呈下降趋势外，在整个21世纪以及所有RCP下，融雪的贡献也将保持高于历史时期。我们的流量持续时间曲线分析表明，未来预计高流量和中流量将增加，而低流量将减少。这些发现提供了宝贵的见解，涵盖了在设想的未来气候中来自喀喇昆仑山脉西部的水的不确定性范围，这将有助于更好地管理下游水资源。