The relative contributions of alpine and subalpine ecosystems to the water balance of a mountainous, headwater catchment
The relative contributions of alpine and subalpine ecosystems to the water balance of a mountainous, headwater catchment
复制标题
DOI：
10.1002/hyp.10526
复制
发表时间：
2015-10
影响因子：
3.2
通讯作者：
J. Knowles;A. Harpold;R. Cowie;M. Zeliff;H. Barnard;S. Burns;P. Blanken;Jennifer F. Morse;M. Williams
中科院分区：
文献类型：
--
作者：
J. Knowles;A. Harpold;R. Cowie;M. Zeliff;H. Barnard;S. Burns;P. Blanken;Jennifer F. Morse;M. Williams
气候变化正在影响高海拔山区生态系统的水文，对生态系统功能和下游人口的水资源供应产生影响。我们直接和连续测量降水和蒸散量（ET）从亚高山森林和高山冻原部分的一个单一的集水区，以及在集水出口的排放通量，量化的山区，河源集水区在科罗拉多，美国的水平衡。在2008年至2012年期间，水平衡关闭平均每年90%，集水ET是最大的水输出量，占降水量的66%。阿尔卑斯山ET是最大的冬季，部分原因是从吹雪，从27%至48%的高山，和6%至9%的集水平衡，分别贡献升华。亚高山ET在夏季达到峰值。高山地区产生了大部分的集水流量，尽管只覆盖了集水面积的31%。虽然平均年高山径流效率（流量/降水量; 40%）大于亚高山径流效率（19%），亚高山径流效率是更敏感的降水量的变化。蒸发和干燥指数的年际分析显示，在集水区尺度上持续存在水分限制，尽管阿尔卑斯山在潮湿和干燥的年份中交替处于能量有限和水分有限的状态。相对于Budyko型模型的预期，每个生态系统通常都会过度产生排放。高山和集水产量相对不受年度气象变化的影响，但这种解释是依赖于用于量化潜在ET的方法。我们的研究结果表明，正确解释高山树线上下不同的水文循环对于量化高海拔山区集水区在气象变化期间的水平衡至关重要。版权所有© 2015约翰威利父子有限公司.
Climate change is affecting the hydrology of high‐elevation mountain ecosystems, with implications for ecosystem functioning and water availability to downstream populations. We directly and continuously measured precipitation and evapotranspiration (ET) from both subalpine forest and alpine tundra portions of a single catchment, as well as discharge fluxes at the catchment outlet, to quantify the water balance of a mountainous, headwater catchment in Colorado, USA. Between 2008 and 2012, the water balance closure averaged 90% annually, and the catchment ET was the largest water output at 66% of precipitation. Alpine ET was greatest during the winter, in part because of sublimation from blowing snow, which contributed from 27% to 48% of the alpine, and 6% to 9% of the catchment water balance, respectively. The subalpine ET peaked in summer. Alpine areas generated the majority of the catchment discharge, despite covering only 31% of the catchment area. Although the average annual alpine runoff efficiency (discharge/precipitation; 40%) was greater than the subalpine runoff efficiency (19%), the subalpine runoff efficiency was more sensitive to changes in precipitation. Inter‐annual analysis of the evaporative and dryness indices revealed persistent moisture limitations at the catchment scale, although the alpine alternated between energy‐limited and water‐limited states in wet and dry years. Each ecosystem generally over‐generated discharge relative to that expected from a Budyko‐type model. The alpine and catchment water yields were relatively unaffected by annual meteorological variability, but this interpretation was dependent on the method used to quantify potential ET. Our results indicate that correctly accounting for dissimilar hydrological cycling above and below alpine treeline is critical to quantify the water balance of high‐elevation mountain catchments over periods of meteorological variability. Copyright © 2015 John Wiley & Sons, Ltd.