Study of beach morphology has been one of the most important issues in coastal engineering research projects.Because of the existence of two important coastal areas located in the north and south parts of the Iran,in the present study an analysis of the coastal zone behaviour is made.Bed level elevations are measured and compared with the theoretical equilibrium profile.It is shown that the behaviour of the coastal zone in the region is consistent with the Dean (1991) equilibrium profile.In the next stage,following extensive investigations,the bed level changes due to arise in sea level at different locations in the surf zone are estimated.The mechanism of beach re-treatment due to a rise in sea level is considered based on the simplified model of Dean (1991) in which the mass balance of the sediments is taken into account.Comparison of the equilibrium profiles for different cases of sea level rise,clearly shows that because of the sediment transport induced by the fluctuation of the water level,the beach profile in the surf zone changes accordingly resulting in an erosion in the inner region of the surf zone and an accumulation of sediments towards the offshore.