2014 Volume 20 Pages 73-78
The impediment of water flow caused by spreading of Phragmites australis can’t be ignored in the maintaining of the river cross-section. Previous studies have shown the effectiveness of a storage pond and a shielding slab for interrupting progress of the underground root. In this study, four proto-type trenches are proposed and the field surveys were carried out. Survey contents are density of vegetation, mud sedimentation, water quality in trenches and benthos habitat around trenches. The storage trenches worked to prevent the growth of Phragmites australis. Also, the shield plate divided the group of vegetation and it means the possibility of vegetation control in the river bank. Surveys of mud sedimentation reveal that the sedimentation rate was different in each trench depending on each structure. In addition, the mud accumulation in a trench was predicted by using a function of the submergence number of times, mud density and inflow of SSC. According to the multivariate analysis, water quality in a trench is subject to the inflow of fresh water or sea water, nutrients, and photosynthesis activity.
