Slowly varying stokes waves and submarine longshore bars

We investigate the mass transport velocity in the Stokes boundary layer due to slowly varying Stokes waves impinging on and reflecting from a plane-sloping beach. The resulting mass transport velocity distribution is interpreted to indicate the possible locations of submarine longshore sandbar formation. It is found that the number of bars is likely to increase when the bottom gradient is slight and that the spacing between the crests of the bars increases seaward for some distance offshore. These results are in qualitative agreement with field observations.