Investigation of Distribution of Velocity and Turbulence Intensity in Presence of Dunes and Vegetation in a Rectangular Open Channel

Formation of bed forms, such as dunes, is a prominent feature in natural open channel flows with sediment transport. Knowledge of turbulent flow over sand dunes is needed to understand the interaction between the flow, the bed forms and the associated sediment transport. This study presents results of an experimental work aimed at investigating the effect of different dunes and vegetated banks on flow velocity, Reynolds stresses and turbulence intensities. Experimental measurements were made over fifth and sixth dunes in a series of ten of 2-dimensional asymmetric gravel dunes which had dune height of 4 and 8 cm, respectively. These dunes had a mean wavelength of 100 cm, mean lee slope angles of 28º, and width equal to the flume width. Rice stems with a median diameter of 2.7 mm and a stem distribution density of 400 stem/m were used to cover the flume banks for simulating vegetation on riverbanks. From experimental measurements, the effect of different heights of crest of gravel dunes on the characteristics of flow in vegetated flume; and the reattachment points for different heights of crest of gravel dunes were investigated.