School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Islamabad, Pakistan.
Department of Geography, University of Zurich, Switzerland.
Sci Total Environ. 2020 Feb 10;703:135010. doi: 10.1016/j.scitotenv.2019.135010. Epub 2019 Nov 3.
The complex snow and glacier (cryosphere) dynamics over the "third pole" mountainous regions of the Karakoram-Hindukush-Himalayas (HKH) makes this region challenging for accurate hydrological predictions. The objective of this study is to investigate the impacts of climate change on major hydrological components (precipitation-runoff, snow- and glacier-runoff, evapotranspiration and inter-annual change in streamflows) over the Hunza-, Gilgit- and Astore-River basins, located in HKH. For this purpose, three different hydrological models (snowmelt runoff (SRM), HEC-HMS and HBV are tested over snow- and glacier-covered river basins. These are subsequently integrated with the climate projections simulated from regional climate models (RCMs) developed under CORDEX-SA experiments. The basin-wide RCM-simulations for future scenarios exhibited an increase in precipitation but decline in intensity of rise over high-altitude zones. The temperature rise showed a maximum increase during monsoon by 4.18 °C, 4.37 °C and 4.34 °C over Hunza-, Gilgit- and Astore-River basins, respectively, for the period 2071-2099 (2090s) and a high emission scenario (RCP8.5). Further, in response to rise in precipitation and temperature, the SRM simulations showed a significant increase in snow- glacier-melt runoff (49%, 42% and 46% for SRM) and precipitation runoff (23.8%, 15.7% and 27% for HEC-HMS) in the Hunza-, Gilgit- and Astore-River basins, respectively, for the 2090s under RCP8.5. The streamflow projections for SRM showed a shift in hydrological regime with an increase by 369 (168.4%), 216.5 (74.8%) and 131.8 m/s (82%) during pre-monsoon in the Hunza-, Gilgit- and Astore-River basins, respectively and then decline by -73.2 m/s (-13.9%) and -45.4 m/s (23.4%) during monsoon of the 2090s, in the Hunza- and Astore-River basins, respectively, under RCP8.5. Overall, the projections show that the pre-monsoon and monsoon seasons are expected to be strongly influenced by climate change, through alterations in snow- and glacier-accumulation, and melt regimes with substantial consequences for river runoff in the region.
“第三极”喀喇昆仑-兴都库什-喜马拉雅（HKH）山区的复杂冰雪（冰冻圈）动态给准确的水文预测带来了挑战。本研究的目的是研究气候变化对位于 HKH 的 Hunza、Gilgit 和 Astore 河流域主要水文组成部分（降水-径流、雪和冰川-径流、蒸散发和年际径流量变化）的影响。为此，在雪盖和冰川覆盖的流域上测试了三种不同的水文模型（融雪径流（SRM）、HEC-HMS 和 HBV）。随后，将这些模型与 CORDEX-SA 实验下开发的区域气候模型（RCM）模拟的气候预测进行了整合。未来情景的全流域 RCM 模拟显示，降水增加，但高海拔地区的上升强度下降。温度上升在季风期间最大，Hunza、Gilgit 和 Astore 河流域分别增加了 4.18°C、4.37°C 和 4.34°C，这是在 2071-2099 年（2090 年代）和高排放情景（RCP8.5）期间。此外，由于降水和温度的上升，SRM 模拟显示在 2090 年代 RCP8.5 下，Hunza、Gilgit 和 Astore 河流域的雪-冰川融雪径流（SRM 为 49%、42%和 46%）和降水径流（HEC-HMS 为 23.8%、15.7%和 27%）显著增加。SRM 的流量预测显示，水文状况发生了变化，在 Hunza、Gilgit 和 Astore 河流域，季风前的流量分别增加了 369（168.4%）、216.5（74.8%）和 131.8 m/s（82%），然后在 2090 年代季风期间下降了 -73.2 m/s（-13.9%）和-45.4 m/s（23.4%），在 Hunza 和 Astore 河流域，分别在 RCP8.5 下。总体而言，这些预测表明，通过改变雪盖和冰川积累以及融化模式，前季风期和季风期预计将受到气候变化的强烈影响，这将对该地区的河流径流量产生重大影响。
