Effect of Secondary Flow on Hydraulic Geometry in Meandering Rivers

Hydraulic geometry is a term to state that a relationship between channel shape and discharge at-a-station or downstream of a reach. Channel shape means cross-sectional geometry (i.e., width, depth), together with hydraulic parameters (i.e., bed slope, mean velocity) for a given water and sediment discharge. In this study, a general concept of hydraulic geometry is initially dealt with; thereafter, continuity, flow resistance, sediment load and secondary flow equations are applied to develop a semi-analytical model for downstream hydraulic relation. The secondary flow appears in the relations by the ratio of radial to longitudinal shear stresses. Further on, Hey and Thorne (J Hydraul Eng ASCE 112(8):671–686, 1986) field data in Britain are used to calibrate the model, and this indicates a reasonable agreement between observed and calculated values with average error between 17.101 and 30.204% which may partially be owing to the assumptions made in the model. In the end, sensitivity analysis is accomplished to identify the parameters to which the model is most sensitive.