Impacts of subsurface hydrologic conditions on rill sediment transport capacity

JOURNAL OF HYDROLOGY

卷:591

Article

Wang, Shuyuan¹  Flanagan, Dennis C.^1,2  Engel, Bernard A.¹  Zhou, Na³ 

[1] Purdue Univ, Dept Agr & Biol Engn, 225 South Univ St, W Lafayette, IN 47907 USA

[2] USDA ARS, Natl Soil Eros Res Lab, 275 South Russell St, W Lafayette, IN 47907 USA

[3] Hebei Univ Econ & Business, Coll Management Sci & Engn, 47 Xuefu Rd, Shijiazhuang 050000, Hebei, Peoples R China

关键词: Subsurface hydrology;    Sediment transport capacity;    Rill flow;    Equilibrium condition;   

DOI  :  10.1016/j.jhydrol.2020.125582

来源: Elsevier

【 摘 要 】

Sediment transport capacity (T-c) is the equilibrium sediment transport value under steady-state flow and channel conditions. Given the difficulties in controlling hydrologic parameters close to steady-state in the field, most previous studies measured transport capacity in the laboratory on either non-erodible beds or erodible beds without drainage. However, infiltration under drainage conditions and exfiltration under seepage conditions cannot be ignored in the real world, and their impacts on soil strength and water discharge may affect transport capacity. The objective of this study was to estimate the effects of subsurface hydrologic conditions on rill sediment transport capacity, and the observations are discussed under both detachment-limited and transport-limited conditions. Series of experiments were carried out with a relatively uniform sand using three water discharges on a 4.56% slope flume with four rills from 0.5 to 3.0 m long under four subsurface hydrologic conditions varying from free drainage to 10 cm seepage head. The determination of equilibrium sediment transport capacity was based on the spatial change of sediment transport as slope lengths increased and the elevation change of the erodible surface in rills. Results from 107 runs indicated that there was only one equilibrium sediment transport value for a given surface and subsurface hydrologic condition, given similar observations were obtained under detachment-limited and transport-limited conditions. For the studied sand, observed critical shear stress decreased around 20% from the drainage to the saturation condition, and decreased slightly from the saturation to the seepage condition. Measured transport capacity increased 13% to 15% from drainage to seepage conditions for the studied water discharges, which was the result of decreased soil strength and increased water discharge. The differences in transport capacities between drainage and saturation increased as water discharge increased, but the differences between saturation and seepage were relatively stable for all studied water discharges.

【 授权许可】

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