GIS支持下的长江干流江苏段河道冲淤分析

【作者】 刘平；

【导师】 王建； 高正荣；

【作者基本信息】 南京师范大学 ， 第四纪地质学， 2006， 硕士

【摘要】 长江下游河道及环境演变的研究意义重大，进展也比较迅速。与长时间段的河床冲淤平衡研究相比，近期河道冲淤(从20世纪50年代至今)的研究对长江下游的防洪、航道的开发、港口的布局等更具有实践意义。 本文全面论述了基于GIS的河道冲淤分析的技术路线、方法体系和工作流程，通过建立长江干流江苏段水下地形数据库，进行了长江干流江苏段河道冲淤分析，并结合水沙变化条件进行了河道演变影响因素的综合分析，总结了长江干流江苏段河道近期冲淤演变的特性，得到以下结论： (1) GIS技术是定量研究河道冲淤演变的一种有效手段，克服了传统的地形断面法和输沙量法在河道冲淤分析实际应用中存在计算精度不够高、空间分析能力差等缺陷，可以为河床演变研究、河道工程建设、防灾减灾措施的制定提供有力的支持。 (2) 80年代中期前长江干流江苏段河道总体冲淤演变趋势为淤积，此后以冲刷为主。分别属于河流段、过渡段、潮流段的三段河道冲淤趋势也表现为先淤积再冲刷，并且大致同步。其中，潮流段在整个时间段(1963年-2003年)内表现为冲刷，过渡段和河流段表现为淤积，80年代中期以后河流段与过渡段的冲淤幅度几乎一致。 (3) 上述河道冲淤规律与期间来水来沙条件的组合变化息息相关：年平均径流量在80年代中期以后有所增加，而输沙量却由于上游梯级水库的修建、水土流失的治理等原因减少了很多，这造成了前后淤积与冲刷的转换。 (4) 分汊河段的冲淤变化反映在某一汊道冲刷，而另一汊道淤积，使得部分主支汊互为兴衰、交替发展；单一弯道的冲淤变化反映在凹岸发生冲刷，凸岸发生淤积；节点控制河段深泓位置几乎不变，稳定性较好，但水深可能会随水沙等条件变化发生相应的淤积或冲刷。 (5) 位于顺直河段的江心洲，多数呈窄长的梭形，洲头洲尾比较稳定，支汊一侧有所淤涨，当其近岸时，有并岸的趋势；位于鹅头分汊型河段的江心洲也是向抗冲性差的一岸发展，同时还向下游发展，使汊道发育成鹅头型；江心洲多更多还原

【Abstract】 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.更多还原