| It is meaningful to research the evolvement of channel and environment of lower reaches of Yangtze River, which develops rapidly. Compared with the research of channel scouring and siltation for a long period, the research of recent channel evolvement from 1950s is more significative to prevent flood, to exploit channel, and to plan port and so on.We discuss the technic-route, method-system, and work flow of the calculation based on GIS. By setting up the database of the channel in Jiangsu Province, we analyse the channel evolvement in Jiangsu Province, discuss several factors about channel evolvement, and summarize the characteristics of recent channel evolvement in Jiangsu Province. The primary results of the paper are obtained:(1) GIS is one of the effective methods to research channel evolvement, which excel at precision and spatial analysis, and should be studied further for practical application.(2) The lower reaches of Yangtze River silted before middle of 1980s, and scoured from then. River-flow reach, intergradation reach, and tidal current reach also did synchronously.(3) The result above-mentioned of channel scouring and siltation is related to the runoff and the soil mass: the annual mean runoff increased after middle of 1980s, while the soil mass decreased because of the building of upriver reservoir and the protection of water and soil, and so on.(4) The scouring and siltation of bifurcated channel stretch appears that one side scours and another side silts. So some primary inlets and subordinate inlets develop alternately. The scouring and siltation of curved reach appears that the concave bank scours and the convex bank silts. The position of talweg controlled by nodes changes rarely, but the talweg will scour and silt with the change of the runoff and the soil mass. |
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