【作者】 李茂田；

【导师】 陈中原；

【作者基本信息】 华东师范大学 ， 自然地理学， 2005， 博士

【摘要】 长江流域面积为180万km~2,是我国第一、世界第三大河流。长江以她占全国18%的国土面积,养育了全国34%的人口,创造了国民生产总值(GDP)的40%以上。长江是我国内河航运最发达的河流,内河货运量与周转量均占全国的80%以上。素有“黄金水道”之嘉誉,但目前大部分干、支流航道仍处于天然状态,滩槽冲淤变化多端,对航运影响较大。另外中下游洪灾却十分频繁,日益成为危害长江“健康”的最主要环境问题。尽管导致洪灾频发的原因多样,但长江中游泥沙淤积严重,洪水位不断上涨的趋势却是不争的事实。在这种情况下,深入研究河流现代河床地貌演变与水沙的耦合作用,定量阐明不同河段水沙的变化与冲淤变化的相互关系,具有深刻的实践指导意义。另外水沙与河床地貌演变的耦合研究是流体运动力学、泥沙运动力学、河床演变等学科交叉与边缘领域,因此,开展长江中下游河床地貌变化及其与水沙的耦合作用研究,无疑具有重要的理论意义。 基于以上的考虑,第一,本文运用实测和历史的水沙资料,探讨了长江中下游干流河道洪枯季水沙与冲淤的分布特征及其相互关系。研究发现:1)长江干流流量、悬沙浓度与输沙量在洪峰期(7月)前后随时间的递变率不同,输沙量从上游到下游都表现为洪峰前递增率大于洪峰后递减率,流量和悬沙浓度的变化在汉口以上表现为洪峰前递增率大于洪峰后递减率,但汉口以下表现为洪峰前递增率小于洪峰后递减率;2)汉口以上比降在增水过程中随流量增加而减小,减水过程中随流量减少而增加。汉口以下比降在增水过程中随流量增加而增加,减水过程中随流量减少而减少。3)悬沙的粒度洪细枯粗,床沙的粒度洪粗枯细;悬沙与床沙的粒度都具有沿程递减的趋势;4)悬沙中冲泻质含量的变化为洪季大、枯季小,过渡质含量的季节变化与冲泻质变化相反;5)床沙中冲泻质与过渡质含量变化为洪季低、枯季高,床沙质含量的季节变化与冲泻质和过渡质变化相反;6)悬沙浓度与流量,输沙量与流量之间的关系都表现为正相关关系,相关性表现出明显的沿程递减的特性,这种特性与悬沙中过渡质含量的沿程递减密切相关;7)宜昌—新厂河段与螺山-汉口河段总体上表现为枯季淤积,洪季冲刷;新厂—螺山河段与汉口—大通河段总体上表现为枯季冲刷,洪季淤积。更多还原

【Abstract】 The Changjiang River is the largest river in China, with a drainage area of 1.8×10~6 km~2.Wandering 6300 km eastward to the East China Sea, it contributes 9 ×10~11 m~3 of fresh water and 4.7 ×10~8 t of sediment into its estuary and the East China Sea each year. Meanwhile, GDP of the Changjang drainage basin accounts for 40% that of China. The Changjiang channel is well known as "Golden river channel" for it is one of the biggest river transport lines in China. However, the river channel in the middle Changjiang is affected strongly by sediment erosion and deposition, and flood disasters tends more frequent in the last century. River channel evolution has significant impacts on flood discharge, shipping and the sustainable development of Chanjing drainage basin. This has arisen numerous water conservancy projects that have been constructed in the Changjing River drainage basin during recent decades. Anthropogenic perturbations have caused considerable changes in water and sediment discharge movement. It is important to study the middle and low Changjiang river channel erosion-deposition evolution for integrate utilizing and exploiting the Changjiang river channel, and the river evolution is always international advanced research area of land surface integrant process.On the basis of the long-term historical discharge and sediment database, the present study firstly discussed seasonal variation of water and sediment discharge. The main results are as follows: 1) the water discharge and sediment load was increase before flood peak and decrease after flood peak. The rate of water and sediment increase is larger than the rate of water and sediment decrease in channel up Hankou station, the rate of water increase was smaller than the rate of water decrease in channel down Hankou station; 2) the suspended sediment particulate diameter was fine in flood season and was coarse in dry season. The riverbed particles were coarse in flood season and fine in dry season. Moreover, the suspended sediment and riverbed particles showed a decrease trend from upstream downward; 3) the wash load of suspended sediment concentration (SSC) in flood season was higher than that in dry season. The seasonal variation of bed load of SSC was just reversal while compared with the variation of fine suspended sediment; 4) it was positive correlation between water discharge and sediment load, and the value of correlation coefficient decreased from upstream downward; 5) the evolutionshowed siltation in dry season and erosion in flood season at Yichang-Xinchang channel section and the Luoshan-Hankou channel section, and the evolution showed reversal changes at Xinchang-Luoshan section and Hankou-Datong section while comparing with above river sections.Secondly, we constructed Digital Elevation Mode (DEM) of the middle and low Changjinag River channel and rationally simulated main river channel evolution on the basis of the Yichang-Wuhan River Relief Map in 1983 and 1997, and the Wuhan-Jiangyin River Relief Map in 1972 and 2002 (1:10000). This technology can quantitatively expresses temporal-spatial distribution of riverbed erosion-deposition such as cross-section profile, vertical profile, isobaths and erosion-deposition volume. On the other hand, based on classical hydrology dynamical theory, we made use of the field measured data, and studied the coupling interaction for water velocity and riverbed erosion and deposition, suspended sediment concentration and riverbed erosion, riverbed particles and the riverbed erosion and deposition. The main results were as follows: 1) 5159×10~8tons sediment were output from riverbed of Yichang-Wuhan river section from 1983 to 1997, and 3.83×10~8 tons sediment were output from riverbed of Wuhan-Jiangyin river section from 1972 to 2002, this riverbed erosion mainly resulted from increase dams construction; 2) the middle and low Yangtze River channel can be divided as follow sections. Yichang-Gongan erosional section, Shishou-Jianli depositional section, Shangchewan-Honghu erosional section, Luxikou-Wuhan depositio更多还原