EVOLUTION OF TIDAL FLAT PROFILES UNDER THE INFLUENCE OF LAND RECLAMATION IN JIANGSU PROVINCE

With the increasing development of tidal flats along the northern Jiangsu coasts in recent years, the impacts of human activities on tidal flats become much remarkable. The elevation data along 9 tidal flat profiles were collected over the Jianggang (Tiaozini) tidal flat during the land reclamation stage from 2007 to 2012. On the basis of the seabed elevation data, a quadratic model was established to investigate the evolutionary mechanisms of tidal flat profiles responding to land reclamation, combined with the grain size data of surface sediments. Our results indicate that the shapes of tidal flat profiles in north non-reclamation area are concave, since the accretion rate is higher on the upper intertidal zone than on the lower intertidal zone. The reclamation increased the accretion rate of tidal flat and caused rapid accretion on the lower zone in reclaimed area, which induced the curvature of the profiles to be slowing down. After reclamation, the sediment grain over the tidal flat without tidal effects tended to be finer than that over the vicinity of the non-reclaimed tidal flat. Reclamation dikes built in the lower intertidal zone blocked the flood current from entering into the original intertidal zone. The fine sediment from the sea deposited on the seaward side of the dike, which resulted in a rapid accretion on the lower intertidal zone. It made the non-reclamation tidal flat profile changed into a slightly concave shape.