2006年特大枯水期间长江中下游河床沙与悬沙沿程变化特征  

VARIATION OF BED-LOAD AND SUSPENDED SEDIMENT ALONG MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER DURING THE PERIOD OF THE EXTREME LOW DISCHARGE IN 2006

作　　者：闫虹[1] 戴志军[1] 李九发[1] 赵军凯[1] 张小玲[1] 陈吉余[1] 

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200062

出　　处：《长江流域资源与环境》2008年第A01期82-87,共6页Resources and Environment in the Yangtze Basin

基　　金：上海市科委重点基金资助项目(062512076);上海市科技启明星资助项目(06QA14016)

摘　　要：基于2006年10月长江中下游沿程不同断面的河床沙、悬沙以及流速等相关水文泥沙现场观测资料,采用数理统计学与泥沙运动力学相结合的方法,对极端气候与流域重大工程作用下,长江中下游水沙的沿程变化以及悬沙与河床沙交换等进行分析。流量自宜昌向下游方向总的趋势是沿程增大,观测时段与多年同期平均流量(33 500 m3/s)相比少了近57%,而在沙市河段流速最大值达1.1 m/s;近底层水体含沙量较低,平均值为0.079kg/m3,与多年平均(50年)含沙量相比减少了90%。大通站实测悬沙含量与多年10月平均相比减少了近86%;河床沙组成以细砂和中砂为主,悬沙组成以粘土和粉砂类为主。与多年平均值相比,河床沙变化并不大,悬沙显著细化。中游河段河床沙中略细的粘土和细粉砂组分含量较上下游为多,而悬沙中略粗的中粗粉砂组分含量较上下游为多,断面垂向差异大;同时,从水流、含沙量、河床沙和悬沙颗粒组成及河道类型等多因素同步分析,表明长江中游河道泥沙交换相对频繁,河床稳定性相对较差,下游河道泥沙交换相对较少,河床稳定性相对较好。Based on the hydrological data including current velocities, bed loads and suspended sediments in the different segments along mid-lower reaches of the Yangtze River （MLRYR） in October 2006, both changes of water and sediment and exchanges between bed-load and suspended sediment in the Yangtze River in response to the extreme low discharge and impounding of the Three Gorge Reservoir were discussed by combined methods of sediment dynamics and statistical techniques. The results shown as follows：It was an increased trends for the discharge along the MLRYR, The discharge during the surveyed period was nearly 57% lower than that in the same period of the normal years, l here was the biggest value of 1. 1 m/s for the current velocity occurred in the Shashi gauge station along MLRYR. The relatively low suspended sediment concentration （SSC） could be found in the near bottom layer,and the average SSC of 0. 079 kg/ma was 90% lower compared with those during 1955-2005. In addition,the SSC measured in Datong Station in Oct. 2006 was 86% lower compared with those in the same period during 1955-2005. The bed-load of the MLRYZ was mainly composed of fine sand and medium sand, and the suspended sediment was mainly composed of clay and silt. Meanwhile, the change of composition in bed-load and suspended sediment was respectively small and obvious fine compared with those in the normal years. The percent of medium and fine sand in bed load located in the middle reaches was larger than those in the upper and lower reaches. Similarly,the percent of relatively coarse silt in suspended sediment located in the middle reaches was larger than those in the upper and lower reaches. In addition, based on the analysis of multi-factors including current, SSC, bed-load, grain size composition of suspended sediment and river channel type,it could be indicated that middle reaches of the Yangtze River has relatively poor stability due to frequent exchange of sediment in this region. However, the lower reaches of Yangtze River has rela

关 键 词：长江中下游 特枯水情 河床沙 悬沙 泥沙交换 

分 类 号：TV87[水利工程—水利水电工程] TV142.3