Improved interrill erosion prediction by considering the impact of the near-surface hydraulic gradient
Improved interrill erosion prediction by considering the impact of the near-surface hydraulic gradient
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DOI：
10.1016/j.still.2020.104687
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发表时间：
2020-09
影响因子：
6.5
通讯作者：
Chenfeng Wang;Bin Wang;Yunqi Wang;Yujie Wang;Wen-ming Zhang
中科院分区：
文献类型：
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作者：
Chenfeng Wang;Bin Wang;Yunqi Wang;Yujie Wang;Wen-ming Zhang
在复杂条件下，细沟间侵蚀过程的机理尚不清楚。近地表水力梯度的时空变化是一种常见现象；然而，很少有人尝试表征近地表水力梯度以预测侵蚀。因此，本研究的目的是通过考虑近地表水力坡度的影响来确定外生侵蚀力(降雨、坡面水流和渗流)对细沟间侵蚀过程的影响。在粘壤土中设置了5种近地表水力坡度(70%田间持水量、田间持水量、饱和度、0.20和0.40 m承压渗流)，在30、60和90 mm h−1三种降雨强度下，分别采用8.7%和17.6%的坡度。结果表明，除降雨强度(I)、径流(Q)和坡度(S)外，近地表水力坡度是细沟侵蚀过程中的主导因素。在基于水蚀预报概念的细沟侵蚀预报方程中引入近地表水力坡度因子后，细沟侵蚀速率的预报精度显著提高(R2= 0.92，纳什-萨克利夫模拟效率 = 0.92)。R2和NSE值比现有经验公式(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，流速是预测细沟侵蚀速率的关键水力参数。细沟侵蚀速率可用流速的简单幂函数来预测(R2= 0.88， =NSE 0.88)，但这种关系缺乏明确的物理意义。细沟侵蚀速率与径流深度、降雨强度、静水压力水头和坡度呈幂函数关系增加(R2= 0.88， =0.88)。考虑到外源侵蚀动力对细沟侵蚀的综合影响，采用包含水动力参数、降雨强度和静水压力水头物理描述的幂函数来预测细沟侵蚀速率(R2≥ 0.85，NSE≥ 0.86)。这项研究的结果为开发基于过程和机理的细沟侵蚀过程模型提供了新的见解。
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). TheR2andNSEvalues 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.