Reclamation impacts on the evolution of the tidal flat at Chongming Eastern Beach in Changjiang estuary
滩涂围垦对崇明东滩演化影响的遥感研究

The Chongming Eastern Beach continues to expand owing to sediment deposition from river basins and the nearby ocean. Since the 1960s, the eastern coastline of the beach has extended about 10 km seaward and more than 150 km2 of the tidal flat has been enclosed by embankments for reclamation. This study investigated the influence of these embankments on the evolution of the tidal flat. CORONA, Landsat and SPOT images covering Chongming Eastern Beach were collected to investigate the changing features of the tidal flat from 1965 to 2011.The results indicate that the extension of the flat accelerated after embankments were established. The rate of extension was greater in the first three years following construction; however, the average rate decreased as less sediment was transported from the river basin to the estuary. The construction of embankments also modified the direction of extension from north and northeast to southeast. The reflected tidal currents caused by embankments and the development of tidal creeks destroyed the vegetation cover outside the banks, leading to diffuse catchments that eventually transitioned to large areas of bare flat. This phenomenon repeated with embankments constructed at different times. The merging of the Tuanjiesha sandbank with Chongming Eastern Beach is meaningful for the study of new arising sandbank in the north channel.