Influence of layout angles on river flow and local scour in grouped spur dikes field

• Published in: Journal of hydrology (Amsterdam) 2022-11, Vol.614, p.128502, Article 128502
• Main Authors: Han, Xun, Lin, Pengzhi, Parker, Gary
• Format: Article
• Language: English
• Subjects: 3D numerical model; Flow motion; geomorphology; Grouped spur dikes; hydraulic flumes; Layout angle; Local scour; mathematical models; river flow; rivers; sediments; stream channels
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2022.128502

•A fully-three-dimentional scouring numerical model is developed to investigate the flow and sediment motion in the grouped spur dikes system built in river engineering for the purposes of environmental protection and ecological conservation.•The flow properties, sediment moving and geomorphology in two sets of grouped spur dike cases with most commonly used layout styles, namely the normal-angled spur dikes case and the 45 degree downward-angled spur dikes case are discussed based on the simulation results.•The influence of flow conditions, sediment parameters and spur dike layout angles on the maximum scour depth and their coordinates are analyzed through amounts of additional simulations, which could offer guidance for the structure safety and protection project construction.•The simulations of flood passage through the spur dike fields are conducted to demonstrate the dynamic process of sediment transport and scour development under an unsteady flow condition. The flow properties, sediment moving and geomorphology in the grouped spur dikes field have always been of interest in river engineering. In this paper, a 3D numerical model is employed to investigate the flow motion and riverbed scouring around grouped spur dikes with different layout angle styles. Series of flume experiments are introduced to verify this model’s reliability before its application on the simulation of the downward-angled spur dikes case and normal-angled spur dikes case respectively, and detailed comparative analyses on the flow intensity, vortex patterns and local scour are made for these two layout angle styles respectively, in which the similarities and differences could both be found. Then the influence of flow conditions, sediment parameters and spur dike layout angles on the maximum scour depth and their coordinates are discussed through additional simulations, while the different correlations show between the maximum scour depths with these three factors. Then the simulation of flood passage through the spur dike fields is conducted, which could not only provide river hydrological information but also offer guidance for the hydraulic structure safety.