2022 年 10 巻 1 号 p. 404-414
This study investigated sediment release from the bottom outlet of a dam using 3D numerical simulations of turbidity current and bed deformation. A numerical model was developed by customizing the opensource computational fluid dynamics library OpenFOAM. The erosion of cohesive sediment was modeled based on previous experimental results. The numerical model was validated using field measurements of sediment release. The field data obtained after the sediment release operation indicated the existence of a scour hole expanding laterally in front of the entrance of the bottom outlet. The numerical simulations accurately reproduced this scour hole. The concentration of turbidity (suspended solids, SS) was also quantitatively accurately simulated. The contribution of the scouring process to SS was evaluated based on the results of the simulations. The numerical simulations revealed that in some time intervals, sediment is temporarily efficiently eroded during sediment release. The developed numerical model and findings of this study should be useful for optimizing the operation of sediment release gates to mitigate reservoir sedimentation by cohesive sediments.
