Diversion Properties of Sediment Bypass Facilities Using Three-Dimensional Sediment Transport Model

Regarding sediment bypassing operation, real case study is very limited to only Miwa dam or Koshibu Dam in the Tenryu river. Therefore, further study is needed in order to assess quantitative efficiency of sediment bypassing based on reservoir geometry, hydraulic conditions and deposited sediment property. We have developed a three-dimensional sediment transport model that can calculate the bed deformation and complex flow around the diversion facility. We compared the numerical and experimental results on diversion facilities and confirmed the validity of the model. Using this model, we performed calculations by varying the particle size of sediment, the slit width of diversion facility and flow rate. Based on these calculation results, we investigated three dimensional effects on sediment deposition and discharging process from upstream of diversion weir to sediment bypass tunnel. Finally, we have discussed sediment bypassing ratio and proposed empirical equations with sediment properties and diversion facilities.