Bed shear stress in non-uniform flow

Bed shear stress is an essential parameter in the description of flow motion and sediment transport. Several methods have been proposed to estimate bed shear stress under uniform flow conditions, yet few are applicable to non-uniform flow. A new approach is proposed to compute bed shear stress for non-uniform flow. This approach combines the Saint–Venant method, vertical two-dimensional numerical model and numerical differential method. The computed bed shear stress of this approach shows good consistency with Cardoso and Graf’s measured data, with the maximum difference less than 14 %. The new approach is compared with Yang’s method, and the maximum difference between these two methods is 25 %. This difference comes from the ignored term in Yang’s derivation. By adding the ignored term, the maximum difference reduces to 8 %. This new approach is suitable to calculate bed shear stress in non-uniform flow.