A hydropower system is often managed to achieve maximum performance. In a watershed where the silting phenomena is significant, this type of operation may cause a high rate of reservoirs silting. This paper describes a mathematical model which uses a transport equation of the solid phase (suspension and bed load) to study the progressive silting of two reservoirs Daesti and Rm. Vilcea on the Olt river cascade development in Rumania. Various regimes of oepration were simulated as well as their influence on reducing silting during the flood.