An estimate of the cross-shore sediment flux at the boundary of the coastal zone

A method based on mathematical modeling of the near-shore dynamics is suggested to calculate the annual mean cross-shore sediment flux q* at the coastal zone boundary. This method is applied to several sand coast profiles located in various geographical regions and exposed to energetic impacts of different scale. It is shown that the fluxes can be either positive (directed to the shore) or negative, and the magnitudes found agree with the known estimates based on other approaches. A conclusion is made that the resulting direction of q* is controlled by moderate storms with regime cumulative exedence from 1 to 10%. The wave periods, bottom slope, and sediment grain size play a special role in the process. An empirical criterion is found that allows one to predict the direction of the sediment flux crossing the coastal zone boundary.