The influence of reservoirs on floods. Case study on the Bezid reservoir Lake Bezid, created with a complex purpose (water supply, flash attenuation, tourism) colects the waters of the Cusmed hydrographyc basin, from a surface of 157 km.p., basin positioned in the Transilvanian lower mountains, in the Tarnava Mica sector. The arrangement of the hydrographical basins involves desicions involving the geomorfologycal modifications of the natural water courses and requires a data base for the preddiction of the solid transport on natural and arranged regime. The following of the processes that are taking place in beds of the rivers are underlining the diversity of the factors that are affecting the flood and the complexity of the interdependence between them.