An Experimental Study on Effects of Rainfall, Inflow and Slope Gradient on Ephemeral Gully Slope Erosion in Chinese Mollisol Region
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State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau,Institute of Soil and Water Conservation,Northwest A F University,Yangling

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S158

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    Abstract:

    Understanding effects of rainfall intensity, inflow rate and slope gradient on hillslope ephemeral gully erosion can provide a scientific basis for controlling soil erosion in the Chinese Mollisol region. This study designed two rainfall intensities (50 and 100 mm/h) and two slope gradients (3° and 7°), and five inflow rates under four combinations of two rainfall intensities and two slope gradients to analyze impacts of rainfall intensity, inflow rate, slope gradient and their interaction on slope soil erosion with ephemeral gully, and to quantify the contribution of ephemeral gully erosion to slope erosion. The results showed as follows: (1) The impact of slope gradient and inflow rate on slope soil erosion was greater than that of rainfall intensity. Under the five inflow rates, when the rainfall intensity increased from 50 mm/h to 100 mm/h, the slope erosion on the slopes of 3° and 7° increased by 52.3%-81.8% and 29.4%-88.4%, respectively; when the slope gradient increased from 3° to 7° , the slope erosion increased by 114.3%-395.5% and 130.0%-320.9%, respectively; when the inflow rate increased from 15 L/min to 75 L/min, the slope erosion increased by 4.6-13.5 times. The increase of inflow rate aggravated slope gradient influmce on slope erosion while weakened rainfall intesisty impacts on slope eroiosn. (2) The effects of rainfall intensity-inflow rate-slope gradient interactions, and inflow rate-slope gradient interactions on slope erosion were the largest impact, followed by the rainfall intensity-inflow rate interaction, and the interaction of rainfall intensity-slope gradient had the lowest impact. Ephemeral gully erosion occupied above 85% of total slope erosion at the different experimental treatments, which increased with inflow rate and slope gradient. (4) The slope erosion rate had positively significant correlations with the flow velocity, shear stress and stream power, while it had negatively significant correlation with the friction coefficient. Compared with the flow velocity and shear stress, the correlation between slope erosion rate and stream power was best.

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History
  • Received:June 08,2023
  • Revised:August 10,2023
  • Adopted:August 31,2023
  • Online: January 27,2024
  • Published: