Effect of sediment supply on flow characteristics in a meandering channel

Abstract

Meandering channels widely exist in natural rivers, especially in lowland alluvial plains. In this research, a meandering channel is designed, in order to explore the effect of sediment supply on flow characteristics in it. In this channel, the water level, three-dimensional instantaneous velocity, and riverbed elevation are measured by digital wave altimeter, three-dimensional acoustic Doppler velocimeter (ADV) and three-dimensional laser scanner, respectively; and the flow characteristics with (first case) and without sediment (second case) supply are compared. The results showed that under the same discharge, the transversal slope of water surface in the first case is larger than the second case, and its change is steeper; the longitudinal change degree of water surface in the upper half bend is small, and that is large in the lower half bend. By increasing the water discharge, the number of secondary flow vortices at the apex of meandering channel is increased. The trend of the two mainstream lines, with and without sediment supply, are roughly opposite, and the difference between them decreases with increasing the discharge. In addition, the lateral and vertical turbulence intensity of the flow near the outer bank are larger under the two cases. The turbulent kinetic energy of the cross-section is larger in the first case near the bed and water surface.