Author(s): Jan Sieben; Arno M. Talmon

Linked Author(s):

Keywords: Bed-load transport; dune; fixed-bed experiment; helical wake flow; oblique bed form; river

Abstract: In rivers, dune crest patterns are not always perpendicular to the main flow direction, because deviations up to around 20° have been observed. These can affect the direction of sediment transport, but the available predictors for models do not account for this effect. Therefore, laboratory tests on sediment transport over artificial dunes oblique to the flow direction were conducted. The largest effect is due to helical flow at the lee side of a dune and from flow near the reattachment point. These three-dimensional features are lumped into a preliminary predictor to account for the direction of bed-load in models for two-dimensional river morphology with depth-averaged flow. To include dynamic bed-form orientation, an additional model for bed-form orientation is proposed. These concepts require further validation with mobile-bed observations and subsequent tests with numerical simulations.

DOI: https://doi.org/10.1080/00221686.2011.566252

Year: 2011