2003 年 9 巻 p. 73-78
Recently sediment bypass systems have been planned and constructed as effective countermeasures against sedimentation in several reservoirs. Nowadays how to control the behaviors of fine sediment has become important in order to make management of these systems or other similar systems more effective. In this study we conduct some practical consequences on basis of observations and analyses in Miwa Dam, where a redevelopment project is just being carried out. At first we confirmed typical density variation of fine suspended solids flowing into reservoirs during one flood period. We analyzed the behavior of fine suspended load in the reservoir using longitudinal-vertical 2-dimensinal simulation models. This showed relocating outlets of reservoir in the lower and proper level is effect to release high turbid water out of reservoir. We also observed movement of fine sediment mass on reservoir bed, caused by lowering reservoir water level. This can be applied to gather sediment in reservoirs. Consequently we indicate some practical and effective methods to prevent inflow of fine suspended load and reduce sedimentation in reservoirs.
