A Changing Hydrological Regime: Trends in Magnitude and Timing of Glacier Ice Melt and Glacier Runoff in a High Latitude Coastal Watershed
A Changing Hydrological Regime: Trends in Magnitude and Timing of Glacier Ice Melt and Glacier Runoff in a High Latitude Coastal Watershed
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DOI：
10.1029/2020wr027404
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发表时间：
2020-03
影响因子：
5.4
通讯作者：
Joanna C. Young;E. Pettit;A. Arendt;E. Hood;G. Liston;J. Beamer
中科院分区：
文献类型：
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作者：
Joanna C. Young;E. Pettit;A. Arendt;E. Hood;G. Liston;J. Beamer
与其他淡水水源相比，冰川融化水具有独特的生物地球物理特征，在高纬度沿海地区的水文和生态状况中发挥着至关重要的作用。今天，随着世界各地的冰川呈现持续的负质量平衡，冰川径流在数量和时间上都在发生变化，对基础设施、生态系统和生态系统资源可能产生下游影响。然而，在降雨量变化较大的沿海系统中，径流趋势可能很难检测到。在这里，我们使用耦合的能量平衡和水量分配模型SnowModel-Fluflow来研究1980至2016年间阿拉斯加东南部朱诺冰原西部径流的时间和大小的变化。我们发现，在冰川持续质量损失(−0.57±0.12m w.a−1)下，与径流有关的几个水文变量呈现增加的趋势。这包括年度和春季冰川融冰量(+10%和+16%十年−1)，由于降水比例较高，这意味着冰川径流(+3%和+7%十年−1)和流域总径流(+1.4%和+3%十年−1)的增幅较小。这些结果表明，朱诺西部冰原流域在达到“峰值水”之前，仍处于冰川径流增加的时期。在时间方面，我们发现最大冰川融化发生得更早(2.5天十年−1)，这表明在初夏向下游输送的淡水的来源和质量发生了变化。我们的发现突出表明，即使在降水量变化很大的海洋气候中，高纬度沿海集水区也正在经历由持续的冰川质量丧失所驱动的水文状况变化。
With a unique biogeophysical signature relative to other freshwater sources, meltwater from glaciers plays a crucial role in the hydrological and ecological regime of high latitude coastal areas. Today, as glaciers worldwide exhibit persistent negative mass balance, glacier runoff is changing in both magnitude and timing, with potential downstream impacts on infrastructure, ecosystems, and ecosystem resources. However, runoff trends may be difficult to detect in coastal systems with large precipitation variability. Here, we use the coupled energy balance and water routing model SnowModel‐HydroFlow to examine changes in timing and magnitude of runoff from the western Juneau Icefield in Southeast Alaska between 1980 and 2016. We find that under sustained glacier mass loss (−0.57 ± 0.12 m w. e. a−1), several hydrological variables related to runoff show increasing trends. This includes annual and spring glacier ice melt volumes (+10% and +16% decade−1) which, because of higher proportions of precipitation, translate to smaller increases in glacier runoff (+3% and +7% decade−1) and total watershed runoff (+1.4% and +3% decade−1). These results suggest that the western Juneau Icefield watersheds are still in an increasing glacier runoff period prior to reaching “peak water.” In terms of timing, we find that maximum glacier ice melt is occurring earlier (2.5 days decade−1), indicating a change in the source and quality of freshwater being delivered downstream in the early summer. Our findings highlight that even in maritime climates with large precipitation variability, high latitude coastal watersheds are experiencing hydrological regime change driven by ongoing glacier mass loss.