SHORELINE SHIFTING AND MORPHOLOGY CHANGES OF THE TIDAL FLAT-SHALLOW SEA AREA OFF HUANGHUA HARBOR

Shoreline surveys were carried out on the coastal zone near Huanghua Harbor.Two annual monitoring intertidal cross sections were launched on both sides of the Port. Combined with historical data and through illustrations comparison,the shoreline shifting and morphology changes of the tidal flat-shallow sea area were studied comprehensively.Results show that:(1)in the past 50 years,the shoreline near Huanghua Port(Laolangtuozi and Dakouhe coastal zone)has experienced a widespread retreat due to erosion.However,starting from 1980s,especially since the 1990s,the construction of Huanghua Harbor and Bohai New Area have made the shoreline moved forward towards the sea from Laolangtuozi to Fengjiapu.On the contrary,the shoreline around Dakouhe have remained retreating state because there is lack of human activities,and the Huanghua Port acts as a barrier to break the longshore current.(2)Huanghua Port construction has resulted in a high-rate sedimentation on Laolangtuozi in the north side of the harbor;the Dakouhe tidal flat in the south side of the Harbor,howerver,has no apparent change happened in the upper part,and siltation has only happened in the lower part based on the data from 2005 to 2007.Compared with the data of 1980s,it suggests that the slope of the tidal flat has become smaller.(3)In the past 30 years,with the decrease in river process and the increase in marine hydrodynamics,a middle-late stage abandoned delta and a tidal channel-lagoon system have been formed.Since 1995, with the construction of Huanghua Harbor,the marine hydrodynamic system has changed locally to be a force in shaping the morphology of shallow sea area,but the available data indicate that the impact is limited to the north tidal flat and the sea area near the sand embankment of the port.