3D SIMULATION OF THE EFFECT OF SPUR DIKES SPACING ON BED DEFORMATION, FLOW AND PERFORMANCE EVALUATION IN MEANDERING CHANNELS

The spacing is an important consideration in spur dikes design. In meandering channels, the flow field and sediment transport are affected by both the spur dikes and channel sinuosity. The paper employed a 3D model to investigate the effect of the spacing between spur dikes on bed deformation and flow in meandering channels under different sinuosity. The results showed that severe local scour occurred near both the most upstream spur dike and spur dikes downstream of the meander apex. As the spacing increased, complete scour holes emerged starting from the downstream spur dikes, the potential bank erosion became larger, and the flow near spur tips became more turbulent with a large velocity gradient. The maximum local scour depth increased with the spacing and decreased with the channel sinuosity in most cases. The non-uniform spacing could be used to lower the construction cost, and different sinuosity required different spacing arrangements. Based on the simulation results, the performance of different spacing was quantitatively evaluated simply by considering four factors of bank protection, structural stability, construction cost, and aquatic habitat.