Publication Date:
2019
Description:
Abstract
The effects of root systems on soil detachment by overland flow are closely related to vegetation types. The objective of this study was to quantify the effects of two gramineous roots (Paspalum mandiocanum with shallow roots and Pennisetum giganteum with deep roots) on soil detachment capacity, rill erodibility and critical shear stress on alluvial fans of benggang in southeast China. A 4 m long and 0.12 m wide flume was used. Slope steepness ranged from 9% to 27%, and unit flow discharge ranged from 1.39×10‐3 to 4.19×10‐3 m2 s‐1. The mean detachment capacities of Paspalum mandiocanum and Pennisetum giganteum lands were 18% and 38% lower than that of bare land, respectively, and the effects of root on reducing soil detachment were mainly reflected in the 0‐5 cm soil layer. The most important factors in characterizing soil detachment capacity were root length density and soil cohesion, and soil detachment capacity of the two grass lands could be estimated using flow shear stress, soil cohesion, and root length density (NSE=0.90). With the increase in soil depth, rill erodibility increased, while shear stress decreased. The mean rill erodibilities of Paspalum mandiocanum and Pennisetum giganteum lands were 81% and 61% as much as that of bare land, respectively. Additionally, rill erodibilities of the two grass lands could be estimated as an exponential function by root length density and soil cohesion (NSE=0.88). The mean critical shear stress of Paspalum mandiocanum and Pennisetum giganteum lands were 1.29 and 1.39 times that of bare land, respectively, and it could be estimated with a linear function by root length density (NSE=0.76). This study demonstrated that planting of the two grasses Paspalum mandiocanum and Pennisetum giganteum could effectively reduce soil detachment and enhance soil resistance to erosion on alluvial fans, with the deep roots of Pennisetum giganteum being more effective than the shallow roots of Paspalum mandiocanum. The results are helpful for understanding the influencing mechanism of root systems on soil detachment process.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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