Spur dikes are used primarily for protecting levee from erosion during flood in alluvial rivers by means of velocity reduction and flow deflection mechanisms. Recently, their environmental functions are taken into account since they can create diverse riverbed configurations, such as deposition and local scour. However, an impermeable spur dike is exposed to severe local scour and sometimes they are broken down. Meanwhile, it is known that effects of a permeable spur dike, such as pile-group, on flow structure and bed deformation are reasonably mild (Zhang et al. 2005, Sadat & Tominaga 2013). Therefore, the combination of permeable and impermeable spur dikes is useful to provide suitable conditions for ecological aspects.
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