Numerical simulation of sedimentation process in reservoirs and development of a non-coupled algorithm to improve long-term modeling

This paper investigates the validity of a quasi-steady approximation for sediment transport and presents a new algorithm based on this concept. The developed non-coupled algorithm interacts among hydrodynamic, sediment, and morphology modules which are based on depth-averaged Navier-Stokes equations for the flow, the three-dimensional equation of conservation of sediment, and the mass balance between the bed and sediment (Exner equation) to simulate the reservoir sedimentation process. The non-coupled algorithm solves both the short-term scale and the relatively long-term scale problems of reservoir sedimentation. The proposed algorithm is verified using field data and by comparison with other accurate algorithms. Based upon the results of this investigation, the developed algorithm can be used to simulate long-term reservoir sedimentation while considerably decreasing the computational costs and preserving computational accuracy. The computational cost of the non-coupled algorithm is about 97% less than the conventional semi-coupled approach whereas the errors (Root Mean Square Error, Average Relative Error, and Maximum Relative Error of bed level) of the developed algorithm are approximately 15% greater than those for the semi-coupled algorithm for the average value.