College of Resources and Environment,Southwest University,Key Laboratory of Eco-environments in Three Gorges Reservoir Region,Ministry of Education
Supported by the National Key Research Developmental Program of China (No.2016YFC0502303) and National Natural Science Foundation of China (No.41771312)
喀斯特槽谷区地表出露岩石与坡面成不同夹角显著改变地表集中水流特性，进而影响地表侵蚀过程。目前，不同岩石与坡面夹角下的坡面集中流侵蚀水动力特征动态变化过程还不清楚。通过室内模拟放水冲刷试验，研究了6个岩石与坡面夹角角度（30°、60°、90°、120°、150°、180°）、3个坡度（10°、15°、20°）、3个流量（5、7.5、10 L·min-1）组合条件下喀斯特槽谷区坡面土壤侵蚀率与水动力学变化过程。结果表明：在各岩石与坡面夹角下，随冲刷历时的推延，土壤侵蚀率（E）先波动性减小后逐渐趋于稳定，水流功率（ω）呈波动变化但趋势不明显，单位水流功率（Up）逐渐减小，水流剪切力（τ）和过水断面单位能量（ε）波动性逐渐增大；夹角150°时平均土壤侵蚀率（0.078 kg·m-2·s-1）最大，随着夹角增大，τ、ω和ε均呈先减小后增大，Up整体呈减小的变化趋势，各夹角下水动力学指标间差异均显著（P<0.05）；E、τ、ω和Up随坡度和流量的增大而增大，ε随流量增大而增大，随坡度变化不明显；试验条件下，E与τ（R2=0.603）、ω（R2=0.600）和Up（R2=0.583）间的关系用幂函数方程描述较好，与ε间的关系则用线性方程描述较好（R2=0.294）；相比而言，水流剪切力可更好地描述喀斯特槽谷区不同岩石与坡面夹角坡面的土壤侵蚀率。研究结果为揭示喀斯特槽谷区不同岩石与坡面夹角下坡面集中水流侵蚀水动力学机制提供了理论依据。
【Objective】The angles formed by exposed rocks and slope surface in a Karst trough area significantly change the hydrodynamic characteristics of the concentrated flow caused by surface runoff convergence. This process of rill erosion is closely related to hydrodynamic characteristics. Thus, it is essential to explore the hydrodynamic characteristics of concentrated flow erosion on a slope at different angles between the rocks and slopes in a Karst Trough Valley area. 【Method】An indoor scouring experiment was designed having six angles between rock and slope, three slope gradients and three inflow rates to study variations of soil erosion rate and hydrodynamic parameters.【Result】The results showed that with scour duration going on, the soil erosion rate first decreased and then tended to be stable. Also, the stream power and shear stress fluctuated but the trend was not obvious. It was also observed that the unit stream power gradually decreased while the unit energy gradually increased. When the angle was 150°, the average soil erosion rate was largest at 0.078 kg·m-2·s-1. With the increase in angle, the shear stress, stream power and unit energy decreased at first and then increased while the unit stream power decreased as a whole. Under the experimental conditions, the soil erosion rate, flow shear force, flow power and unit flow power increased with change of slope gradients and inflow rates. Importantly, the unit energy of the flow cross-section increased with an increase in inflow rates, but this change was not obvious with the slope gradients. The differences of hydrodynamic indexes among the angles were significant (P<0.05). The relationship between soil erosion rate and shear stress (R2=0.603), stream power (R2=0.600) and unit stream power (R2=0.583) was better described by the power function equation, while the relationship between soil erosion rate and unit energy of flow section was better described by linear equation (R2=0.294). Nevertheless, it was better to use shear stress to describe the soil erosion rate on the slope with different angles between rocks and slope in Karst Tough Valley area. 【Conclusion】This study may provide a theoretical basis for revealing the hydrodynamic mechanism of concentrated flow erosion under different angles between rocks and slopes in a Karst Valley area.
ZENG Rongchang, ZHANG Yuqi, HE Binghui, LI Tianyang, ZHANG Haixiang. Hydrodynamic Characteristics of Concentrated Flow Under Different Angles Between Rock and Slope in the Karst Trough Valley Area[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202107190368,[In Press]