Preferential flow patterns in forested hillslopes of east Tibetan Plateau revealed by dye tracing and soil moisture network
Preferential flow patterns in forested hillslopes of east Tibetan Plateau revealed by dye tracing and soil moisture network
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DOI：
10.1111/ejss.13294
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发表时间：
2022-07
影响因子：
4.2
通讯作者：
Fei Wang;Genxu Wang;J. Cui;Li Guo;C. R. Mello;E. Boyer;Xiangyu Tang;Yi Yang
中科院分区：
文献类型：
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作者：
Fei Wang;Genxu Wang;J. Cui;Li Guo;C. R. Mello;E. Boyer;Xiangyu Tang;Yi Yang
通过土壤和风化层的优先流（PF）导致剖面内快速的垂直和横向水运动。由于该地区下垫基质复杂，土壤较浅，下垫腐岩较厚，并且冰碛和风化残余物质的综合作用，因此对该地区的PF进行量化具有挑战性。我们开发了将染料示踪与高频土壤水分监测网络相结合的新方法，以表征不同森林山坡（针叶林和阔叶林）上的PF路径和数量PF频率。染料示踪实验表明，上层土壤（10-50 cm）的土壤-根界面和深层土壤（50-100 cm）的土壤-岩石界面是主要的PF通道，大岩石对水的渗透深度有强烈的影响。高频土壤水分网络显示，针叶林和阔叶林的平均土壤水分网络频率分别为67.8%和71.7%。在两种森林坡地中，土壤深层PF的发生频率从坡上向坡下逐渐增加，突出了PF发生在坡下的趋势。除了基质条件（如石质腐石质土壤）外，降水总量和最大强度（如本研究中的穿透）被确定为控制PF发生的因素。相比之下，土壤初始水分条件（10、50和100 cm深度）对PF发生的预测不显著。
Preferential flow (PF) through soil and regolith results in a rapid vertical and lateral water movement within the profile. This study focused on quantifying PF in contrasting forested hillslopes of the Hailuo Valley, located on China's east Tibetan Plateau. Quantifying PF in this region is challenging since the underlying matrix is complex, with shallow soils, thick underlying saprolite, and the combined effect of moraines and weathered residual material. We developed new methods that integrated dye tracing with a high‐frequency soil moisture monitoring network to characterise PF pathways and quantity PF frequency on contrasting forested hillslopes (coniferous and broadleaved). Dye tracing experiments showed that soil‐root interfaces in the upper soil layer (10–50 cm) and soil‐rock interfaces in the deeper soil layer (50–100 cm) were the primary PF pathways and that large rocks strongly influence the percolation depth of water. The high‐frequency soil moisture network revealed that the mean PF frequency was 67.8% and 71.7% in the coniferous and broadleaved forests, respectively. The frequency of PF in the deeper soil layer increased from upslope to the downslope locations on both forested hillslopes, highlighting the tendency for PF to occur downslope. In addition to matrix conditions (e.g., stony saprolite soil), the total amount and maximum intensity of precipitation (as throughfall in this study) were identified as factors that control PF occurrence. In contrast, the initial soil water conditions (at 10, 50 and 100 cm depth) were insignificant in predicting PF occurrence. Results of this field‐based study highlight that PF is a ubiquitous and critical subsurface flow mechanism that regulates rainfall‐runoff relationships in forests of the Tibetan Plateau, underscoring the need to consider PF in hillslope hydrological modelling.