Flow and sediment transport process in vegetated beds: experimental investigation in laboratory flumes

The uncertainty regarding the interpretation of sediment transport phenomena during the transients determines some limitations in mathematical modeling of scouring process. But, quantitative estimate of sediment transport processes is important, especially in river-control engineering and water management projects. To this aim, literature (among others Hoffmans and Booji, 1993; Chrisochoides et al., 2003) shows it is necessary to well predict the flow velocity field, the eddy-viscosity and the bed shear stress in order to make correct calculations in simulating the bed-load transport and the development of scour hole in time. Particularly, the role of turbulent structures, developing within the scour hole, on process evolution is still unclear. In such a context, the present work aims to investigate the effect of flexible vegetation planted on the bed on the flow field, turbulence flow structure and sediment transport process. Results are presented and discussed from laboratory experimental campaigns specifically designed to investigate flow characteristics both in presence and in absence of vegetation on the bed.