A model for formation of transverse bars

An extension of Kennedy's potential model is used to investigate the formation of sand bars normal to a gently sloping beach. The model suffers from drawbacks similar to the ones found in Kennedy's analysis: namely, not much is known about the lag distance δ between fluid waves and bed waves. Nevertheless, the theoretical predictions compare well with several observational studies. The result shows that the spacing between the transverse bars depends on the inverse of the beach slope and on the square of the drift velocities across the bars.