The Application of Two-point Method for Estimation of Flow Hydrodynamic Parameters in Mountainous Cobble-Bed Rivers

The study of mountainous rivers is recently considered by hydraulic researchers. Ten cross sections of a cobble-bed river، Behesht Abad، located in the central Iran were applied in this study. The distribution of velocity profile in cobble-bed and accuracy of two-point method to estimate the parameters of mean velocity and shear velocity were investigated and then the values of flow resistance were evaluated. Shear velocity was calculated by two-point method، and velocity profile and the results were compared by the parabolic and the boundary layer characteristics methods to predict flow resistance function. Results reveal that velocity profiles present S-shape and logarithm distributions. Also the values of mean velocity، shear velocity and flow resistance function calculated by two-point method can be presented with 94. 6، 85. 6 and 84 per cent accuracy، respectively. The results of this study can be extended to apply and to predict flow resistance for other mountainous rivers in Iran.