Long term evolution of tidal flat at the center of Jiangsu Provinceand the influence of Spartina alterniflora growth

A series of benchmarks were setup on the south Chuandong tidal flat (Yancheng, Jiangsu). Monthly observation of the surface elevation has been performed for 7 years (October 2012 to November 2018) using the Rod Surface Elevation Table(RSET). The edge of the Spartina alterniflora was obtained from the remote sensing images. The long-term evolution of the mudflat and the influence of growth of Spartina alterniflora were evaluated. Results show that: the subsurface processes (e.g., soil expansion and compression) is the key factor affecting the evolution of mudflat at the highest position of the tidal flat. The growth of salt marsh increases the amount of sediment deposition. With the propagation of the edge of salt marsh, the annual sediment deposition at the central salt marsh decreases gradually. In the vicinity of the frontier of the salt marsh, the annual siltation volume increases. Even though, the bare flat evolution trend is hardly affected by the advancing of salt marsh. From the landside to seaside, the cross-shore profile can be divided into 4 zones, which are erosion-deposition balance, rapid deposition, erosion-deposition balance and rapid erosion zones, respectively. The slope of the intertidal flat increases evidently. The tidal flat resources decrease constantly in the past 7 years.