Sediment transport in a 90-degree diversion: Experimental and conceptual approach

Fluvial diversions are systems with a highly 3-dimensional flow structure that has an influence on the water and sediment discharge distribution between both downstream branches. Geometrically they are characterized by having a downstream branch parallel to the upper channel and a lateral branch that forms a certain angle with the aforementioned. In these conditions, field and laboratory observations show that a disproportionate amount of sediment deviates into the lateral branch. The objective of this study is to analyze the flow characteristics and their relationship with sediment transport in the diversion area. Experiments with different total discharges were carried out in a 90-degree diversion laboratory model. Results show that total discharge determines the bed topography patterns near the diversion which, in turn, influence in the flow characteristics and sediment discharge distribution. Main flow variables were also measured and laser and visual observations were used to determine sediment trajectories in the diversion.