Temporal-spatial Variation of the Channel in Jiangsu Reach of the Yangtze River during the Last 44 Years
长江干流江苏段44 年来河道冲淤变化的时空特征

River channel sedimentation in the lower reaches of the Yangtze River can be affected by both rising sea level due to global warming and the construction of reservoirs in the upper river that reduces the amount of sand discharge.To evaluate the dynamic changes of sedimentation and erosion of the Jiangsu reach of the Yangtze River(about 330 km in length)from 1958 to 2003,databases of five periods Digital Elevation Mode(DEM)of underwater topography were designed and constructed on the basis of the Jiangsu River Relief Map in 1959,1970,1985,1992 and 2003(1:25000-1:60000).The result indicated that the main course of Yangtze River in Jiangsu Province had experienced an obvious switch from sedimentation to erosion around 1985 because of the decreasing amount of sediment yield from the upper Yangtze River after that year.The sedimentation process in the main course of Jiangsu reach of the Yangtze River demonstrated propulsive phenomena of "down-reach-ward accumulation".Between 1985 and 2003,the erosion rate of the lower segment was greater than those of the middle and upper segments.The reason is probably the bigger shortage of sediment yield due to the decrease of sediment source from the upper reach and the strengthening protection of the bank erosion in the lower reach.