TY - JOUR
T1 - Linking soil macropores, subsurface flow and its hydrodynamic characteristics to the development of Benggang erosion
AU - Tao, Yu
AU - Zou, Ziqiang
AU - Guo, Li
AU - He, Yangbo
AU - Lin, Lirong
AU - Lin, Henry
AU - Chen, Jiazhou
N1 - Funding Information:
This study was funded by the National Natural Science Foundation of China ( 41571258 and 41877013 ) and the National Scholarship Council of China ( 201906760039 ).
Funding Information:
This study was funded by the National Natural Science Foundation of China (41571258 and 41877013) and the National Scholarship Council of China (201906760039).
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/7
Y1 - 2020/7
N2 - The increasing population in south China is exposed to Benggang erosion that deteriorates slope stability and agricultural production. However, the influence of subsurface flow, especially macropore flow, on the development of Benggang erosion and the collapse of Benggang remains inadequately studied. To address this issue, we measured the spatial distribution of soil macropores on an active Benggang-eroded slope in a subtropical region in China. During the experimental period of 20151221 to 20180116, two collapse events were observed on the study slope. In addition, the soil water content at the depths of 20, 40, 60, and 80 cm was monitored at a time interval of five minutes at six sites along the slope. The velocities of vertical subsurface flow traveling between measured soil depths were determined based on the difference in the response time of soil water content to rainfall along the depth. Further, the Reynolds number (Re) of subsurface flow in different water patterns, e.g., Darcy flow (DF) and preferential flow (PF) was calculated based on soil pore size and flow velocity. Results indicate that the number of macropores near the Benggang wall (i.e., the most active area of erosion on a Benggang slope) was almost twice that on the upper slope. The presence of abundant macropores near the Benggang wall facilitated faster subsurface flow and a greater variation in soil water content in time and space, which significantly influenced Benggang erosion and collapse. For both the DF and PF, the maximum Re was detected near the Benggang wall. The Re of PF was ten times higher than that of DF. The Re being greater than 3 was the threshold to initiate PF. Moreover, the larger Re of PF likely enhanced the leaching of fine soil particles and promoted the occurrence of Benggang erosion. This study confirms the key role of macropore flow in Benggang erosion, which helps better understanding, modeling and controlling of Benggang erosion.
AB - The increasing population in south China is exposed to Benggang erosion that deteriorates slope stability and agricultural production. However, the influence of subsurface flow, especially macropore flow, on the development of Benggang erosion and the collapse of Benggang remains inadequately studied. To address this issue, we measured the spatial distribution of soil macropores on an active Benggang-eroded slope in a subtropical region in China. During the experimental period of 20151221 to 20180116, two collapse events were observed on the study slope. In addition, the soil water content at the depths of 20, 40, 60, and 80 cm was monitored at a time interval of five minutes at six sites along the slope. The velocities of vertical subsurface flow traveling between measured soil depths were determined based on the difference in the response time of soil water content to rainfall along the depth. Further, the Reynolds number (Re) of subsurface flow in different water patterns, e.g., Darcy flow (DF) and preferential flow (PF) was calculated based on soil pore size and flow velocity. Results indicate that the number of macropores near the Benggang wall (i.e., the most active area of erosion on a Benggang slope) was almost twice that on the upper slope. The presence of abundant macropores near the Benggang wall facilitated faster subsurface flow and a greater variation in soil water content in time and space, which significantly influenced Benggang erosion and collapse. For both the DF and PF, the maximum Re was detected near the Benggang wall. The Re of PF was ten times higher than that of DF. The Re being greater than 3 was the threshold to initiate PF. Moreover, the larger Re of PF likely enhanced the leaching of fine soil particles and promoted the occurrence of Benggang erosion. This study confirms the key role of macropore flow in Benggang erosion, which helps better understanding, modeling and controlling of Benggang erosion.
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U2 - 10.1016/j.jhydrol.2020.124829
DO - 10.1016/j.jhydrol.2020.124829
M3 - Article
AN - SCOPUS:85082004410
SN - 0022-1694
VL - 586
JO - Journal of Hydrology
JF - Journal of Hydrology
M1 - 124829
ER -
