Skip to main content
ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #337550
Title: Upslope inflow, hillslope gradient and rainfall intensity impacts on ephemeral gully erosion

Author
item XU, XIMENG - Northwest Agriculture And Forestry University
item ZHENG, FENLI - Northwest Agriculture And Forestry University
item Wilson, Glenn
item WU, MIN - Northwest Agriculture And Forestry University

Submitted to: Land Degradation and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2017
Publication Date: 11/1/2017
Citation: Xu, X., Zheng, F., Wilson, G.V., Wu, M. 2017. Upslope inflow, hillslope gradient and rainfall intensity impacts on ephemeral gully erosion. Land Degradation and Development. 28(8):2623-2635. https://doi.org/10.1002/ldr.2825.
DOI: https://doi.org/10.1002/ldr.2825

Interpretive Summary: Ephemeral gullies (EG) are major contributors to sediment loss and soil degradation on cultivated lands. The impacts of topography and rainfall on EG erosion are still unclear on steep hillslopes. A series of laboratory experiments were conducted to investigate these impacts using a large slope adjustable soil pan (8 m-long, 2m-wide, and 0.6 m-deep) and a rainfall and an upslope runoff simulation system. Three representative rainfall intensities (50, 75, and 100 mm h-1), three typical slope gradients (26.8%, 36.4% and 46.6%) and five upslope runoff areas (16, 32, 64, 96, and 128 m2) were tested. The upslope runoff provides inflow into an ephemeral gully channel. The results showed that ephemeral gully erosion increased when rainfall intensity, slope and upslope runoff area increased. Upslope topography and inflow had great impacts on downslope ephemeral gully erosion. The upslope inflow rate was more effective than rainfall intensity in increasing runoff velocities in ephemeral gully channels and thus caused more ephemeral gully erosion when upslope inflow was applied. The product of the upslope runoff area (A) and the square of slope (S) gradient (AS2) was selected to reflect the impacts of topography. A soil loss equation based on rainfall intensity and AS2 was established that can be used to predict the ephemeral gully erosion in various topographic and rainfall conditions on the steep hillslopes.

Technical Abstract: Ephemeral gullies (EG) are major contributors to sediment loss and soil degradation on cultivated lands. However, the topographic and rainfall impacts on EG development processes are still unclear, especially on steep loessial hillslopes like the Loess Plateau. A series of laboratory rainfall simulation experiments were conducted to investigate the impacts of topographical and rainfall characteristics on ephemeral gully erosion on a steep loessial hillslope. A large slope adjustable soil pan (8 m-long, 2m-wide, and 0.6 m-deep) and a side sprinkler rainfall simulation system were used in this study. Three representative rainfall intensities (50, 75, and 100 mm h-1), three typical slope gradients (26.8%, 36.4% and 46.6%) and five upslope drainage areas (16, 32, 64, 96, and 128 m2) were tested. The product of the upslope drainage area and the square of slope gradient (AS2) was selected to reflect the topographic characteristic in this study. The results showed that the ephemeral gully erosion magnitude corresponded well with changing of rainfall intensity, slope and upslope drainage area. Soil loss increased when rainfall intensity, slope and upslope drainage area increased. Upslope topography and inflow had great impacts on downslope ephemeral gully erosion. The upslope inflow rate was more effective than rainfall intensity in increasing runoff velocities in ephemeral gully channels and thus caused more ephemeral gully erosion when upslope inflow was applied. Soil loss equations based on rainfall intensity and AS2 were established and validated, which showed satisfactory accuracy and could be used to predict the ephemeral gully erosion in various topographic and rainfall conditions on the steep loessial hillslope.