长江河口南支河道近期演变与自动调整过程研究

基于长江河口1997年以来大量的数字地形图和水文泥沙实测资料，分析研究了工程影响下南支河段河床自动调整过程。结果表明：三峡水库蓄水以来，在来水量未变、来沙锐减背景下，南支河道水流流态较平稳，而河床持续冲刷，但2006年以后河床冲刷强度减小，现逐渐向冲淤平衡发展；河槽断面趋于窄深，白茆沙和新浏河沙沙体的变化对南支河段的稳定性影响较大，南北港分流口冲淤变化频繁，新浏河沙护滩工程起到了一定的“固滩、限流”作用，但并不能阻止新浏河沙和南沙头护堤前沿河床冲刷的势态。建议对扁担沙沙尾采取适当的工程整治措施。 

Recent evolution and self-adjustment processes of south branch of Yangtze River estuary

Based on the digital topographic map and hydrological sediment data since 1997 and the recent hydrologic field observations, the self-adjustment process of south branch in Yangtze estuary under the influence of Xinliuhe shoal protection works and Three Gorges Project are analyzed. The results indicate that the water fluvial regime is stable and the riverbed is in continuous erosion state under the condition of sharp sediment decrease and unchanged discharge since the completion of Three Gorge Project; the river bed is continuously scoured but the intensity has become smaller and has a new balance tendency since 2006; in the same period, the cross sections are narrower and deeper, the changes of Baimao and Xinliuhe shoals exert significant influence on the stability of the channel; the erosion and deposition of south and north passage bifurcations changes frequently; the constructed Xinliuhe shoal protection works and Nanshatou channel submerged dike projects play a great role in shoal fixing and flow limiting, but can not prevent the trend of intense erosion at the front areas of Xinliuhe shoal and Nanshatou channel. Some effective measures should be taken to the tail of Biandan shoal.