FLAT OF CHONGMING ISLAND AND ITS IMPACTS ON THE SEDIMENT DISTRIBUTION

Tidal creek systems are developed well at the salt marsh on the eastern tidal flat of the Chongming Island. Their formation is closely linked to reclamation of the tidal flat and the width of the salt marsh. Development and evolution of creeks on the mudflat are related to such factors as sizes of tidal basins at the salt marsh, tidal regimes (spring or neap tides), rainfall intensity and so on. The tidal creek systems are on such a small scale that they don't control flood tidal current. In ebbing phase, creeks become main passages for draining and fine suspended sediments and fluid mud that don't aggregate converge toward the creeks, so sediment in creeks is finer than that on the flat. The formation and evolution of creek systems and distribution of sediment on the eastern tidal flat of the Chongming Island,which develops at the rapidly prograding deltaic coast, are completely different from estuarine/bay tidal channel-creek systems in Europe and America, which are dominated by flood current and whose sediments are coarser than those on flat obviously. Comparison study of creek systems on the eastern tidal flat of Chongming Island with other types improves our understanding of the impacts of tidal channel-creek systems on development and evolution of mudflat and salt marshes.