长江入海水沙通量与三角洲演变模式关系  

Relationship between delta evolution and water-sediment fluxes from the Yangtze to the sea

作　　者：杨云平[1] 李义天[1] XUE Guoqiang 

机构地区：[1]武汉大学水资源与水电工程科学国家重点实验室,武汉430072 [2]School of Engineering,University of Glasgow,United Kingdom

出　　处：《水力发电学报》2014年第2期162-167,共6页Journal of Hydroelectric Engineering

基　　金：重大水利工程影响下河口水沙和地貌变化过程(2010CB429002);国家十二五科技支撑项目(2012BAB04B04);中央高校专项基金(201220620212)

摘　　要：为了研究流域水沙变化对河口三角洲演变模式的影响，建立了长江口三角洲地貌演变速率和流域入海水沙通量响应曲线，明确了历史时期和近期入海流量和输沙率改变对三角洲演变模式影响。结果表明：流域入海流量无明显的变化趋势，输沙率和含沙量均表现为阶梯性减小趋势，近期（2003．2010年1流量年内分配比例10月和11月减小，12月至次年3月增加，输沙率洪季减小幅度大于枯季：河口三角洲演变模式经历了淤涨～淤涨减缓～侵蚀的过程，建立了其冲淤速率和流域入海水力要素关系曲线，表明输沙率对三角洲淤涨中贡献大于流量，但大水年或枯水年流量影响不容忽视；近期水沙组合发生明显变化，促使三角洲淤涨的水沙组合比例减少，侵蚀比例增加，平衡状态中，流量引起淤涨比例增加，输沙率引起淤涨比例减少，表明流量在三角洲演变模式中的作用有增强趋势。This study develops response curves of the geomorphic evolution rate of the Yangtze delta and the river basin water-sediment fluxesinto the sea to reveal the influences of water-sediment changes on river delta evolution and to describe the changes in these fluxes caused by the impoundment of Three Gorges reservoir. Results show that the water flux took a trend of little change while the sediment discharge and sediment concentration experienced a stepped decrease.In recent years （2003- 2010）, the flux distribution ratio was decreased in October and November and increased from December to March of the following year, and the decrease in sediment discharge in the flood seasons was greater than that in the dry seasons.The estuary delta experienced evolutionfrom accretion to slower accretion and then to erosion.The curves of erosion rate versus hydraulic elements of the river flow into the sea that were developed in this study, show that the sediment discharge had an impact on the delta accretion greater than thewater flux did, but the latter cannot be neglected for flood years or dry years.Under the significantchanges in the combinations of water and sediment flows caused by thereservoirimpoundment, the proportion of combinationsfavorable for delta accretion was reduced while the one for delta erosion was increased. The equilibrium states showed an increase in the accretionproportion of water flux and an decrease in the accretionproportion of sediment discharge, indicating a trend of the water flux＇s increasingly strongerroleon the delta evolution in recent years.

关 键 词：河流泥沙工程学 通量 输沙率 演变模式 三角洲 长江河口 

分 类 号：P737.1[天文地球—海洋地质]