Author(s): Stefan Haun; Nils Reidar B. Olsen
Linked Author(s): Stefan Haun, Nils Reidar B. Olsen
Keywords: Numerical modelling; RANS-equations; Reservoir deposition; Reservoir Management
Abstract: To simulate erosion and deposition pattern in rivers and reservoirs is still a challenge in numerical modelling. Accurate results depend next to sediment related factors strongly on the simulation of the water flow. In addition to a correct modelling of the free-water surface also the simulation of secondary currents is necessary. The numerical program, used for this study, solves the RANS-equations therefore in three-dimensions. For modelling the turbulence the k-emodel is used and the pressure field is computed by the SIMPLE method. The program uses an adaptive grid which moves accordingly to the changes in the water and bed levels, with the advantage of only modelling the water phase. An implicit free-water surface algorithm is used to compute the water level, based on the pressure field. In this study the simulation of the sediment deposition in the Angostura reservoir in Costa Rica is presented. Through the high sediment inflow in the reservoir a sedimentation rate of about 4-5%of the reservoir volume was detected per year. Field measurements were used to validate the simulated sediment trapping. The results of the calibrated deposition simulation show good agreement between the computed and measured bed elevation changes. Also a comparison of the amount of settled sediments between the measurements and the simulation is presented in the study.
Year: 2012