Recently, maintaining biodiversity in rivers is required as a part of nature-oriented river works. Wandos made artificially in rivers are one of the measures to secure biodiversity. Transport of suspended solids at the water surface of wandos to river stream is known to be controlled by large scale vortices.In this study, firstly transport rates of expanded polystyrene particles as uspended solids at the water surface of a wando in a rectangular channel were examined. The results of experiments in the rectangular channel indicate that the transport rate of expanded polystyrene particles decreases with the increase in Froude number. Secondly, a formula on the transport of expanded polystyrene particles was proposed as a function of Froude number and the ratio between the length and the width of wando.
