Flexible Vegetation Behavior And Effects On Flow Conveyance: Experimental Observations

As it is known, vegetation is an important component of aquatic ecosystems. Because of the variety of species and, thus, of the characteristics of the vegetation elements (form, size, stiffness, etc.), it is difficult to develop a widely applicable method to predict mean flow and flow resistance. Despite the intense activity research, much work has to be done in understanding hydrodynamics in vegetated channels. This is important to analyse many physical processes involved in the ecosystem at different spatial and time scales. In this paper, attention is restricted to flexible vegetation. After a brief description of results obtained in previous experimental works conducted in a rectangular laboratory flume at the Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali – University of Palermo (Italy), the data are used to investigate how stems' concentration and flow submergence affect the mean flow and flow conveyance characteristics in vegetated channels. The results indicate that both these parameters affect the flow profile and flow conveyance characteristics, but flow submergence especially influences the dominant mechanism of momentum exchange between the vegetation layer and the layer above it.