Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 2005
Publication Date: N/A
Shallow overland flow on agricultural land has distinctly different sediment transport characteristics than flow in large channels and streams. The high flow velocities on steep land coupled with often large variations in sediment concentrations stand in contrast with the sub-critical flow regimes and relatively low sediment concentrations in stable stream systems. Yet, erosion prediction models for upland areas use the same sediment transport relationships based on critical shear stress or stream power concepts that are used in large stream flows. There is increasing evidence that greater consideration must be given to the micro-mechanic nature of sediment movement in shallow overland flow that substantially affects the sediment transport capacity and bedform development. This article discusses the results of a highly controlled sediment transport study that shows the sediment transport capacity limiting effect due to a high degree of sediment particle interaction. The key parameters measured were particle velocity and the sediment concentration. The study was conducted in a steady state flow regime to which sediment was added at a controlled rate at the upstream of a 7 m long and 10 m wide channel of about 1º slope steepness. As the sediment addition rate is increased, sediment movement by saltation gives way to an organized structure consisting of a strip that transitions into a meandering bedform. The analysis is based on a two-phase flow model involving the St. Venant equations of shallow water flow and granular flow.