Integrating observations and models to determine the effect of seasonally frozen ground on hydrologic partitioning in alpine hillslopes in the Colorado Rocky Mountains, USA
Integrating observations and models to determine the effect of seasonally frozen ground on hydrologic partitioning in alpine hillslopes in the Colorado Rocky Mountains, USA
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DOI：
10.1002/hyp.14374
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发表时间：
2021-09
影响因子：
3.2
通讯作者：
D. Rey;E. Hinckley;M. Walvoord;K. Singha
中科院分区：
文献类型：
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作者：
D. Rey;E. Hinckley;M. Walvoord;K. Singha
这项研究整合了空间分布的现场观测和土壤热模型，以限制美国科罗拉多州尼沃特岭长期生态研究基地内高山流域内冻土对融雪分区和水流生成的影响。研究区域由两个截然不同的山坡组成，在地形、积雪深度和植物群落组成方面存在显着差异。延时电阻率测量和土壤热模型能够扩展离散土壤湿度和温度测量，以纳入单独的点测量无法实现的尺度和深度的景观变化。具体来说，不均匀的积雪厚度（~0-4 m）和山坡之间的土壤体积含水量（~0.1-0.45）强烈影响季节性霜冻的深度以及冻结前可形成孔隙冰的土壤湿度。不同的霜冻深度和先前的土壤湿度条件预计会产生不同的融雪渗透率和流动路径的拼凑。然而，土壤温度和体积含水量的峰值，以及地下电阻率的下降，揭示了两个山坡上的融雪渗透，这与雪水当量的最初下降和水流的早期增加相一致。潮湿和干燥山坡的土壤温度、土壤湿度和电阻率数据表明，水流的初始增加发生在深层土壤水通量之前。融雪渗透和更深渗滤之间的时间滞后表明，水通过非饱和区的横向运动是早期水流生成的重要驱动力。这些发现提供了弥合规模差距和填充基于物理的低温水文模型所需的基于过程的信息类型，以研究季节性冻结土壤中的地下水文和生物地球化学传输。
This study integrated spatially distributed field observations and soil thermal models to constrain the impact of frozen ground on snowmelt partitioning and streamflow generation in an alpine catchment within the Niwot Ridge Long‐Term Ecological Research site, Colorado, USA. The study area was comprised of two contrasting hillslopes with notable differences in topography, snow depth and plant community composition. Time‐lapse electrical resistivity surveys and soil thermal models enabled extension of discrete soil moisture and temperature measurements to incorporate landscape variability at scales and depths not possible with point measurements alone. Specifically, heterogenous snowpack thickness (~0–4 m) and soil volumetric water content between hillslopes (~0.1–0.45) strongly influenced the depths of seasonal frost, and the antecedent soil moisture available to form pore ice prior to freezing. Variable frost depths and antecedent soil moisture conditions were expected to create a patchwork of differing snowmelt infiltration rates and flowpaths. However, spikes in soil temperature and volumetric water content, as well as decreases in subsurface electrical resistivity revealed snowmelt infiltration across both hillslopes that coincided with initial decreases in snow water equivalent and early increases in streamflow. Soil temperature, soil moisture and electrical resistivity data from both wet and dry hillslopes showed that initial increases in streamflow occurred prior to deep soil water flux. Temporal lags between snowmelt infiltration and deeper percolation suggested that the lateral movement of water through the unsaturated zone was an important driver of early streamflow generation. These findings provide the type of process‐based information needed to bridge gaps in scale and populate physically based cryohydrologic models to investigate subsurface hydrology and biogeochemical transport in soils that freeze seasonally.