Abstract
This manuscript describes an experiment study on the local flow and bed variation around different types of spur dykes in sediment mixtures. The permeable spur dyke, impermeable spur dyke and three kinds of hybrid spur dykes are investigated under non-submerged clear-water scour conditions. The local scour and wake deposition properties and the characteristics of the sediment size distribution due to the differences in the type of the spur dykes are focused on. In general, both the flow structure and the bed properties around a hybrid spur dyke are a combined one of that of a permeable and an impermeable spur dykes. Sand ribbons are observed in the downstream of spur dykes, mainly caused by the sediment sorting in the transverse direction. Desirable flow patterns and bed properties may be achieved by taking full advantages of those of a permeable and an impermeable spur dykes.
