Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China; School of Geographic Sciences, East China Normal University, Shanghai, 200241, China; Key Laboratory for Mountain Hazards and Earth Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China; Julie Ann Wrigley Global Institute of Sustainability, Arizona State University, Tempe, AZ 85287, USA.
The Norwegian Water Resources and Energy Directorate, Norway.
Sci Total Environ. 2018 Dec 10;644:1160-1170. doi: 10.1016/j.scitotenv.2018.07.004. Epub 2018 Jul 11.
Climate warming is expected to accelerate glacier retreat and shift hydrological regime, which poses great threat to regional water resources in terms of amount, variability, and quality. This is especially true in arid regions with glaciers such as the Central Asia. However, few models manage to mimic both glacier runoff and surface changes with adequate performance. To narrow this gap, we integrated a spatially distributed hydrological model (FLEX) and a glacier retreat model (∆h-parameterization), and tested the new model in the Urumqi Glacier No. 1 catchment, which is best monitored in China. The model inputs include climate forcing, topographic map and initial ice thickness. Here we validated the model with runoff observation at downstream and glacier measurements, i.e. three historical glacier area maps (1980, 1994 and 2002), annual glacier mass balance (GMB) and equilibrium line altitude (ELA). Results show that the FLEX-∆h model performed well in estimating runoff (with Kling-Gupta efficiency 0.75 for hydrograph) and reproducing historical glacier area variation. Additionally the model generated reasonably spatial distribution of glacier thickness, which is important to examine glacier evolution at the Urumqi Glacier No. 1. Subsequently we ran the model forced by 12 combinations of two climate scenarios and six bias correction methods to assess the impact of climate change on glacier thinning, retreat, and its influence on water resource. The impact assessment shows that glacier area will lose up to a half (54%) of their 1980 extent in 2050, and up to 80% in 2100; while ice volume will decrease up to 79% in 2050, and 92% in 2100. The tipping point (peak water) of glacier melt supply was projected to occur around 2020 and then runoff would decrease significantly. These results alert us that there is a need for immediate mitigation measures to adapt to fast glacier change to assure long-term water security in this region.
气候变暖预计将加速冰川退缩和水文状况的转变，这对包括数量、变异性和质量在内的区域水资源构成了巨大威胁。在中亚等有冰川的干旱地区尤其如此。然而，很少有模型能够以足够的性能模拟冰川径流和表面变化。为了缩小这一差距，我们整合了一个空间分布式水文模型（FLEX）和一个冰川退缩模型（∆h 参数化），并在中国监测最好的乌鲁木齐 1 号冰川流域测试了新模型。模型输入包括气候强迫、地形图和初始冰厚。在这里，我们使用下游径流量观测和冰川测量数据对模型进行了验证，即三张历史冰川面积图（1980 年、1994 年和 2002 年）、年度冰川质量平衡（GMB）和平衡线高度（ELA）。结果表明，FLEX-∆h 模型在估计径流量（水文图的 Kling-Gupta 效率为 0.75）和再现历史冰川面积变化方面表现良好。此外，该模型生成了合理的冰川厚度空间分布，这对于检查乌鲁木齐 1 号冰川的演变非常重要。随后，我们在 12 种气候情景和 6 种偏差校正方法的两种组合下运行模型，以评估气候变化对冰川变薄、退缩及其对水资源影响的影响。影响评估表明，到 2050 年，冰川面积将损失其 1980 年面积的一半（54%），到 2100 年将损失其 80%；而到 2050 年，冰量将减少 79%，到 2100 年将减少 92%。冰川融水供应的转折点（峰值水）预计将出现在 2020 年左右，然后径流量将显著减少。这些结果提醒我们，需要立即采取缓解措施来适应冰川的快速变化，以确保该地区的长期水资源安全。
