عنوان مقاله [English]
Studies of river engineering and River cross structures design such as bridges, diversion dams, Water Intake, etc. have closely related with the accurate calculation of depth, flow velocity and it has estimated moment of maximum flood discharge. The Estimated of flow velocity is important in hydraulic and hydrology studies .where no enough measured data is available, empirical approaches are usually applied to estimate flow velocity and maximum flood discharge. The most of these methods have been proposed for a certain area with specific physical and climatic conditions .to use these methods in other areas with different conditions ,evaluation and analysis of sensitivity of their parameters seems to be necessary. In this research ,new simple and efficient method is used to carry on sensitivity analysis of 2 flow velocity estimation methods including Manning and chezy that both of them are the most famous flow velocity existing. The results show chezy empirical equation is more sensitive Manning equation in estimating flow velocity. At the Manning equation, Model sensitivity is more to the less roughness values and when the energy line slope value (surface water) is high, flow velocity sensitive is increases. In other word, small changes in high slope, the flow velocity has changed dramatically. Sensitivity of Output’s model to hydraulic radius parameter is higher than while the area of catchment increases. Results show that roughness coefficient (c) in chezy equation is the most sensitive parameter and it need to more attention and correction.