Hydrodynamic Characteristics of Concentrated Flow Under Different Angles Between Rock and Slope in the Karst Trough Valley Area
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Supported by the National Key Research Developmental Program of China (No.2016YFC0502303) and National Natural Science Foundation of China (No.41771312)

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    Abstract:

    【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, stream power and unit stream 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.

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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,2023,60(3):762-775.

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History
  • Received:July 19,2021
  • Revised:January 24,2022
  • Adopted:April 12,2022
  • Online: April 19,2022
  • Published: May 28,2023