Effect of vegetation on flows and sediment transport

Abstract

Vegetation is a common feature in natural coastal and riverine waters, interacting with both water flow and sediment transport. However, the physical processes governing these interactions are still poorly understood, which makes it difficult to predict sediment transport and associated morphodynamics in a vegetated environment. In this context, an experimental study was conducted in laboratory with a movable bed trapped in artificial vegetation. The experimental flume is a rectangular open channel 5.75 m long and 0.29 m wide. For flow measurements, the channel is equipped with a fast camera and ADV probe. This work focuses on identifying the vegetation effects on flows and sediment transport. In fact, it was shown that the vegetation presence in a watercourse promotes deposition and sediment accumulation. This is explained by a reduction of the bed shear stress, since the friction occurs mainly by the drag force effect exerted by the vegetation. It was shown too that the vegetation reduced the bedload transport. Thanks to the partitioning of shear stress, it was possible to predict the bedload transport using standard formulas with a reasonable accuracy.

Hydraulic properties affected by litter and stem cover under overland flow

“…Zhao et al (2016) found that overland flow through vegetation stems was affected by grain resistance and vegetation resistance, and the latter was the predominant roughness element, accounting for 80% of the total resistance. Subsequently, Romdhane et al (2018) further confirmed these findings by conducting experiments on an erodible bed with artificial vegetation and concluded that the trapping of sediment by vegetation was attributed to the reduction of the bed shear stress since the drag force due to vegetation was the dominant flow resistance. In addition, some scholars have quantified the two resistance components by modifying Manning's roughness coefficient equation.…”

Role of Vegetation Inducing Sedimentation in an Artificial Earth Channel

“…Given their significance, still regarding the processes in the gutters, the theme has also been investigated in the context of natural channels with natural succession (GURNEL ET AL, 2006;NEPF;GHISALBERTI, 2008;STOFFEL;WILFORD, 2011;CURRAN;HESSION, 2013;HUAI, 2021). Therefore, studies have addressed environments with anthropic control (ADITYA et al, 2010;CHESTER;ROBSON, 2013), artificial channels (SABBATINIA et al, 1998;SILVA, 2018;ERRICO et al, 2020), and laboratory research for simulating vegetation in test channels (ROMDHANE, et al 2018;LI et al, 2022).…”

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“…Given their significance, still regarding the processes in the gutters, the theme has also been investigated in the context of natural channels with natural succession (GURNEL ET AL, 2006;NEPF;GHISALBERTI, 2008;STOFFEL;WILFORD, 2011;CURRAN;HESSION, 2013;HUAI, 2021). Therefore, studies have addressed environments with anthropic control (ADITYA et al, 2010;CHESTER;ROBSON, 2013), artificial channels (SABBATINIA et al, 1998;SILVA, 2018;ERRICO et al, 2020), and laboratory research for simulating vegetation in test channels (ROMDHANE, et al 2018;LI et al, 2022).…”