地理学报 ›› 2014, Vol. 69 ›› Issue (11): 1615-1627.doi: 10.11821/dlxb201411003

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长江口悬沙浓度变化的同步性和差异性

杨云平1,2(), 张明进1, 邓金运2, 李义天2, 樊咏阳2   

  1. 1. 交通运输部天津水运工程科学研究所, 天津 300456
    2. 武汉大学水资源与水电工程科学国家重点实验室, 武汉 430072
  • 收稿日期:2014-08-04 修回日期:2014-08-26 出版日期:2014-11-20 发布日期:2014-12-26
  • 作者简介:

    作者简介:杨云平 (1985-), 男, 黑龙江绥化人, 博士, 从事河口海岸演变研究。E-mail: yangsan520_521@163.com

  • 基金资助:
    科技部项目 (2010CB429002)

The synchronicity and difference in the change of suspended sediment concentration in the Yangtze River Estuary

Yunping YANG1,2(), Mingjin ZHANG1, Jinyun DENG2, Yitian LI2, Yongyang FAN2   

  1. 1. Key Laboratory of Engineering Sediment, Tianjin Research Institute for Water Transport Engineering, Ministry of Transport, Tianjin 300456, China
    2. State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
  • Received:2014-08-04 Revised:2014-08-26 Online:2014-11-20 Published:2014-12-26
  • Supported by:
    Project from the Ministry of Science and Technology of China, No.2010CB429002

摘要:

近年来长江流域入海沙量呈现阶梯性减小趋势,三峡水库蓄水后加剧了这一减小趋势,并通过传递效应影响河口悬沙浓度变化。基于长江口1950-2013年悬沙浓度数据,结果表明:① 长江口南支河段及口外海域悬沙浓度为减小趋势,且越向海域减幅越小,同时与流域入海沙量减幅差距加大;② 北支优势流变化不大,但悬沙浓度为减小趋势,主要为南支和海域大环境悬沙浓度减小所致;③ 拦门沙河段悬沙浓度的峰值区域因径流减小、潮流相对增强,2003-2012年较1984-2002年期间峰值位置向口内上溯约1/6经度,上溯距离洪季 > 年均 > 枯季;④ 1999-2009年南槽进口悬沙浓度减小,主要是再悬浮和滩槽交换引起的悬沙浓度增量小于流域和海域悬沙浓度锐减引起的减量,中段该作用相反,悬沙浓度为增加趋势;⑤ 北槽进口由于分流分沙比减小、流域和海域悬沙浓度减小及再悬浮量减小等综合影响下,1999-2012年逐年的8月份悬沙浓度呈减小趋势,中段越堤沙量作用明显高于外部坏境引起的减小量,为增加趋势。

关键词: 悬沙浓度, 入海沙量, 长江河口

Abstract:

The sediment discharge from the Yangtze River Basin has a stepwise decreasing trend in recent years. The impounding of the Three Gorges Reservoir exacerbated this decreasing trend and affected the change of the suspended sediment concentration (SSC) in the Yangtze River Estuary through the transmission effect. The SSC data of the Yangtze River Estuary during 1959-2012 showed that: (1) The SSC in the South Branch of the Yangtze River in the estuary and in the off-shore sea area displayed decreasing trends and decreased less towards the sea. At the same time, the difference in decreasing magnitude between SSC and sediment discharge became bigger towards the sea; (2) For the North Branch the preferential flow did not change much but the SSC tended to decrease, which was mainly caused by the decrease of SSC in the south branch and East China Sea; (3) Due to the decreased runoff and the relatively strengthened tide, the peak area of the SSC in the bar shoal section in 2003-2012 moved inward for about 1/6 longitude unit compared with that in 1984-2002, and the inward-moving distance was in the order of flood season > annual average > dry season; (4) In the inlet of the South Passage, the SSC decreased mainly because the increase caused by resuspension and shore-groove exchange was less than the decrease caused by the sharp SSC decrease in the basin and the sea areas. The reverse was true in the middle section, where the SSC showed an increasing trend. (5) In the inlet of the North Passage, under the combined influence of decreased flow split and sediment split ratios, decreased SSC in the basin and the sea area and decreased amount of resuspension, the SSC displayed a decreasing trend. In the middle section, because the increased amount caused by sediment going over the dyke was more significant than the decreased amount caused by external environments, the SSC tended to increase. Holistically, the sharp decrease in sediment discharge caused synchronized SSC decreases in the Yangtze River Estuary. But there were still areas where the SSC displayed increasing trends, indicating synchronicity and difference in the response of SSC to the sharp decrease in sediment discharge from the basin.

Key words: suspended sediment concentration, sediment discharge, Yangtze River Estuary