Numerical approach of modelling the sediment transport of the system «Dam-River, Sediment Transport - Deposition»: Case of Sidi Mohamed Ben Aouda (SMBA) dam on oued Mina, in semi-arid area
The constant growth of our need for water requires mobilization of surface water. The construction of dams can be envisaged, but many of them are threatened by early sedimentation; there is clearly a need for tools to quantify and forecast sediment deposition. Reservoir sedimentation can be simulated for different operating periods and understanding the process of sediment transport and deposition is a focus of many approaches: prediction, stochastic modeling, mathematical models and physical models have been used. Multiple interactions exist among bed load sediment, sediment transported near the river bed surface, and suspended sediment, resulting in different modes of transport. This contribution presents a numerical model that allows the simulation of the morphologic behaviour of river bed. The stages of its development are described in detail and the resulting computer code is then applied to a validation site. A section of 17 km is studied, between a dam in service and a hydrometric station located upstream of the dam. Sediment transport in the natural stream is presented by a system of one-dimensional equations describing a water-sediment mixture and translating the laws of conservation. The numerical method used is a finite difference method using an implicit scheme. It is first-order in time and second-order in space. Equations for free surface flow, for unsteady and gradually varied conditions, are used. Combined with the sediment continuity equation, these equations form the Saint-Venant-Exner model. The obtained results show the contribution of bed load transport in the sedimentation of the reservoir in a semi-arid zone.