Two-Dimensional Simulation of Sediment Transport Prediction in Dam Reservoirs Using the Combination of a Numerical Model and GIS (Case Study: Aydoghmoosh Dam Reservoir)

Among the analytical and physical models, numerical models are relatively the best methods for modeling of hydrodynamics and siltation phenomena. Sedimentation in reservoirs is an important issue in the industry of dam building and operating. Therefore assessment and prediction of sediment deposition trend would be one of the most important tools in managing water resources of reservoir dams. Sediment accumulation trend in a reservoir depends on the existing flow pattern and discharge in lake, the geometric shape of the reservoir, the retention time of the reservoir and sediment grain size. This research study has been focused on a two-dimensional numerical simulation by combining a numerical model, remote sensing data and GIS to predict sediment transport process in the Aydoghmoosh dam reservoir. Then, the model solves for the depth-averaged velocity field, suspended sediment transport and siltation. The preparation of initial data has been done in the GIS environment. The depth-integrated Reynolds equations of flow have been used for flow simulation and the depth-integrated advective-diffusion equation has been used to model the suspended sediment transport. Also, the finite difference method has been deployed to discretize the governing equations of flow dynamics and sediment transport, with the algebraic equations were being solved using the ADI method. A highly accurate numerical scheme was also included for modeling the transport of suspended sediment particles by the flow. The mass balance equation was then solved for the bed morphology. The results of numerical modeling were transmitted to the GIS environment and then visualized as maps in different layers. In order to calibrate the numerical model, the results of empirical relationships and experimental models were used. Finally, the results of the numerical model were compared with the satellite images. Sedimentation in the reservoir with regard to the annual flow hydrograph and suspended sediments entering the reservoir has been considered and thus the annual accumulation of sediments in the reservoir has been estimated.