Surface topography can influence flow pathways and the location of runoff source areas and water transport in steep headwater catchments. However, the influence of topography on spatial patterns of residual soil moisture is less well understood. We measured soil volumetric water content (VWC) on 14 dates at 0–30 and 30–60 cm depth at 54 sites on a steep, 10 ha north‐facing forested slope in the west‐central Cascades Mountains of Oregon, USA. Spatial patterns in VWC were persistent over time, and contrary to expectations VWC at 30–60 cm depth was greater on divergent than convergent slopes, especially during wet periods (R² = 0.27, p < 0.001). Vegetation characteristics were assessed for all VWC monitoring locations and soil properties were determined for 13 locations as local factors that affect spatial patterns in VWC. Mean VWC over all dates was negatively correlated to gravimetric rock content (R² = 0.28, p = 0.03) and positively correlated to water storage at field capacity (R² = 0.56, p < 0.01). The variability in rock content in quick‐draining soils influenced soil‐water retention, and by extension, created spatially heterogenous but temporally persistent patterns in VWC. While spatial patterns were persistent, they were not easily explained by surficial topography in a steep, mountainous landscape with rocky, well‐drained soils. Further research is needed to understand if combined soil‐terrain metrics would be a more useful proxy for VWC than terrain‐based wetness metrics alone.

中文翻译：

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局部和非局部因素对陡峭森林集水区土壤水分的影响

地表地形会影响陡峭的源头集水区的水流路径和径流源区域的位置以及水的运输。但是，地形对残留土壤水分空间格局的影响了解得很少。我们在美国俄勒冈州中西部喀斯喀特山脉北部陡峭的10公顷朝北森林坡上的54个站点上，在0–30和30–60 cm深度的14个日期测量了土壤体积水含量（VWC）。VWC的空间格局随时间持续存在，与预期相反，发散坡度上30-60 cm深度的VWC大于会聚坡度，尤其是在湿润时期（R ²  = 0.27，p <0.001）。对所有VWC监测地点的植被特征进行了评估，并确定了13个地点的土壤特性，作为影响VWC空间格局的局部因素。所有日期的平均VWC与重量岩石含量呈负相关（R ²  = 0.28，p  = 0.03），与田间持水量的水储量呈正相关（R ²  = 0.56，p <0.01）。快速排水土壤中岩石含量的变化影响了土壤保水，并由此扩展了VWC的空间异质性和时间持久性。尽管空间格局是持久的，但在陡峭，多山且土壤排水良好的山地景观中，表面地形很难轻易解释它们。需要进一步的研究，以了解与仅基于地形的湿度指标相比，组合的土壤地形指标是否可以更有效地代表VWC。