In this paper, a reformulation of the Bagnold sediment transport formula based on using friction velocity to express bottom shear stress is examined. This modification allows the transport formulation to retain the effect of phase lag between the free stream velocity and bottom shear stress usually associated with flow acceleration or pressure gradient, neglected in Bagnold's original formula. Unlike the original Bagnold model, the modified Bagnold model predicts net onshore sediment transport for asymmetric, zero skewness waves. Results for analytical waveforms of varying velocity amplitude and skewness are qualitatively similar to previous work based on discrete particle and two-phase flow methods. These comparisons suggest that if the simple energetics approach is to be employed, correct estimation of the bottom stress is paramount to predicting sediment transport with any accuracy.
