ABSTRACT
Secondary flows and its interaction with movable bed affect velocity distribution in bends. The basic at-a-station hydraulic geometry equations which are mostly in the form of power-law, relate geometry parameters to discharge at a river reach. Shape factor (r) is the exponent of a hydraulic geometry equation in which depth of water is related to width of its cross-section. In this paper, effect of inclusion of the shape factor (r) on velocity distribution equations was studied. Observations of our previous experiments revealed that strong spiral flows in river bends affect bed topography and consequently alters the value of (r) along the bend. A new equation for predicting longitudinal velocity profile is purposed; coefficients of which were optimized using PSO heuristic algorithm. Tested against experimental data of the present case study, the proposed equation showed a better agreement in comparison with the previous models.
