Floods are natural disasters with higher frequency and considerable damages. Structural evaluations as well as biologic measures are approaches to reduce flood and sediment load of streams. Watershed management is planning, implementation, restoration, development and optimum use of renewable natural resources. Considering the long term use of mechanical structures in Iran, their evaluation for showing their strengths and weaknesses is necessary. The first fundamental step in evaluation of watershed structures is quantifying their effects by measuring their main parameters and the level of achieving their goals. In this study the effect of check dams (drywall dams, Gabions and masonry dams) in Sira – Kalvan watershed on the stream bed slope and flow velocity, time of concentration (Tc) and lag time was evaluated. The results showed that the mechanical operations, which performed in the basin had not any considerable effects on the above mentioned parameters because of insufficient structures and lack of them in some main channels. The results also showed that watershed management projects had positive impact on the river discharge and the best results are achieved from combination of biologic and structural operations.
