NUMERICAL MODELLING OF HYDROPOWER DAM RESERVIOR SEDIMENT REMOVAL IN TRANSIENT CONDITION

In hydraulic projects, deposits and their relevant problems have been always challenging issues, so sediment removal is considered as one of the essential methods in reservoir management. In different methods of sediment removal, flushing technique is known as an economic and convenient method. In this technique, kinetic energy of water is used for removing and transporting deposit particles from reservoir.

Studies have revealed that factors such as position and efficiency of outlets and implementation time of flushing have a drastic impression on operation efficiency. Therefore, determining these factors by means of simulating methods can have a positive effect on future reservoir management. Physical models are usually too expensive and time consuming. But, mathematical models are considered to be more convenient. In this study, a numerical model is developed which can solve the uncoupled one-dimensional governing equation of sediment transport and fluid flow. In each flushing time interval, the Saint-Venant equations are solved and then the resulted hydraulic factors are given to the sediment continuity equation in order to be solved and compute the new bed formation. The sediment transport capacity can be estimated through four empirical formula. One of these formulas requires parameter calibration. This was down through experimental data and then used for a real example. Results of this model have indicated a remarkable accuracy compared with other methods.