Incipient sediment motion in vegetated open-channel flows predicted by critical flow velocity

Sediment suspension affected by submerged rigid vegetation under waves, currents and combined wave–current flows

The prediction of bedload transport capacity in riverbed with aquatic vegetation is a pressing need for river restoration. Laboratory experiments were conducted to investigate the weak bed-load transport rates with emergent vegetation for different energy slopes and vegetation densities. Such rate was observed to increase as the energy slope increased and the vegetation density decreased. The bed shear stress calculated by subtracting the vegetation drag from the total flow driving force was unable to predict the measured bed-load transport rate. On the other side, the estimation of the grain shear stress using the Einstein partitioning method considering the form drag provided a reasonable prediction. On the basis of these results, an explicit formulation for estimating grain shear stress was developed to predict the bed-load transport rate in a vegetated channel by considering the superimposition of forces. In addition, a simple relationship between grain shear stress and total shear stress was established by the boundary layer model. It was inferred that bed-load transport rate decreases with the increase of vegetation blocking factor while the total shear stress remains constant. Comparatively, the proposed models were more accurate than literature models, improving the understanding of the bed-load transport in a vegetated flow. 

Grain shear stress and bed-load transport in open channel flow with emergent vegetation

https://www.pure.ed.ac.uk/ws/files/284794609/Shen_et_al_2022.pdf

Effects of grain composition on the stability, breach process, and breach parameters of landslide dams

河床上的沉没植被的存在能改变水流动结构并且改变沉积运动的状态。在这研究，沉积的早期的运动在一个实验室实验面对在开的隧道的沉没灵活植被被调查。植被与柱体在平行数组安排了的灵活橡胶被模仿。植被密度，水深度，和早期的运动上的沉积谷物尺寸的效果被调查。试验性的结果显示沉积的早期的运动速度作为植被密度减少和水深度和沉积谷物尺寸增加增加。与灵活植物，沉积的早期的运动速度比它没有植被的低，并且比它与僵硬植被的大。一个一般早期的运动速度方程被导出，它能被用于灵活、僵硬的植被条件。

Xuan-yu

Papers

Incipient motion of sediment in presence of submerged flexible vegetation