The mechanism of the interrill erosion process is still unclear under complex conditions. Spatio-temporal variations of the near-surface hydraulic gradient are a common occurrence; however, few attempts have been made to characterize the near-surface hydraulic gradient for erosion prediction. Therefore, the objective of this study is to determine the influence of exogenic erosional forces (rainfall, overland flow, and seepage) on interrill erosion processes by considering the impact of the near-surface hydraulic gradient. Five near-surface hydraulic gradients (70 % of field capacity, field capacity, saturation, artesian seepage at 0.20 and 0.40 m of the hydrostatic pressure head) were applied in clay loam soil at two representative slope gradients of 8.7 % and 17.6 % under three rainfall intensities of 30, 60, and 90 mm h⁻¹. The results showed that the near-surface hydraulic gradient was the dominant factor in the interrill erosion process in addition to rainfall intensity (I), runoff (Q), and slope gradient (S). There was a significant improvement in the prediction accuracy of the interrill erosion rate when the factor of near-surface hydraulic gradient was introduced into the interrill erosion prediction equation based on the Water Erosion Prediction Project (WEPP) concept (R² = 0.92, Nash-Sutcliffe simulation efficiency (NSE) = 0.92). The R² and NSE values were 22.4 %–210.0 % higher than those of existing empirical equations (main parameters: I, I&S, I&Q, I&S&Q). The correlation matrix results indicated that the flow velocity was a key hydraulic parameter for predicting the interrill erosion rate. The interrill erosion rate was predicted well by a simple power function of the flow velocity (R² = 0.88, NSE = 0.88), although this relationship lacks clear physical meaning. We also found that the interrill erosion rate increased as a power function with the runoff depth, rainfall intensity, hydrostatic pressure head, and slope gradient (R² = 0.88, NSE = 0.88). Considering the integrated effect of the exogenic erosional dynamics on interrill erosion, a power function that included the physical description of the hydrodynamic parameters, rainfall intensity, and hydrostatic pressure head was used to predict the interrill erosion rate (R² ≥ 0.85, NSE ≥ 0.86). The results of this research provide new insights into developing process-based and mechanistic models for interrill erosion processes.

在复杂条件下，层间侵蚀过程的机理仍不清楚。近地表水力梯度的时空变化很普遍。然而，很少有人试图描述侵蚀预测的近地表水力梯度。因此，本研究的目的是通过考虑近地表水力梯度的影响，确定外源侵蚀力（降雨，陆上水流和渗流）对层间侵蚀过程的影响。在黏土壤土上施加了五个近地表水力梯度（场容量，场容量，饱和度，静水压头0.20和0.40 m处的自流渗漏的70％），在三个条件下分别以8.7％和17.6％的两个代表性坡度施加坡度30、60和90 mm h的降雨强度^-1。结果表明，除了降雨强度（I），径流（Q）和坡度梯度（S）以外，近地表水力梯度是钻头间侵蚀过程的主导因素。将近地表水力梯度因素引入基于水蚀预测项目（WEPP）概念的钻孔间侵蚀预测方程中，钻孔间侵蚀速率的预测精度有了显着提高（R ²  = 0.92，Nash- Sutcliffe模拟效率（NSE）= 0.92）。的- [R ²和NSE值比现有经验方程式（主要参数：I，I＆S，I＆Q，I＆S＆Q）高22.4％–210.0％。相关矩阵结果表明，流速是预测钻头间侵蚀速率的关键水力参数。通过简单的流速幂函数可以很好地预测钻头间的侵蚀速率（R ²  = 0.88，NSE = 0.88），尽管这种关系缺乏明确的物理意义。我们还发现，层间侵蚀速率随径流深度，降雨强度，静水压头和坡度的增加而呈幂函数关系（R ²  = 0.88，NSE  = 0.88）。考虑对间侵蚀外力作用侵蚀动力学的综合效应，使用的是包括在水动力参数的物理描述，降雨强度，和静水压头的幂函数来预测间侵蚀率（- [R ²  ≥0.85，NSE  ≥0.86 ）。这项研究的结果为钻削侵蚀过程的基于过程和力学模型的开发提供了新的见识。