Acta Geographica Sinica ›› 2009, Vol. 64 ›› Issue (5): 629-637.doi: 10.11821/xb200905012

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Distribution of Surficial Tidal Flat Sediments in the Yangtze Estuary

YAN Hong,DAI Zhijun,LI Jiufa,ZHAO Jianchun,ZHANG Xiaoling   

  1. State Key Lab. of Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China
  • Received:2008-12-05 Revised:2009-03-03 Online:2009-05-25 Published:2009-05-25
  • Supported by:

    Natural Science Foundation of Shanghai,No.07DJ14003;Foundation of Ministry of Science and Technology of China,No.SKLEC-2008KYQN03;Shanghai Youth Science and Technology Venus Program,No.06QA14016


Large-scale and dense sediment samples and associated hydrological data were collected in July 2005 and May 2007 from submarine sectors of Chongming Eastern Shoal, Hengsha Eastern Shoal, Jiuduan Shoal and Nanhui Shoal, which are four important tidal flats located at the mouth-bar river segment of the Yangtze Estuary. Based on the above data, the grain size and related parameters, compositions, classifications in sediments and their distributed characteristics are analyzed, and then mainly impacted dynamic factors on the distributions of sediments are discussed. The results are shown as follows: sediments located at these tidal flats of the Yangtze Estuary are mainly composed of sand, silty sand and silt. The median grain size in sediments is relatively complex with a range from 2.5φ to 8φ. The distributions of sorting coefficients in sediments ranging from 1 to 2 are agreed with that of the median grain size. Moreover, it is suggested that sediments of the tidal flats is coarser, better sorted or finer, and worse sorted. The skewness and kurtosis in sediments are ranged from 0.1 to 0.8 and from 1 to 4, respectively. In addition, the distributions of the grain size parameters, including sorting coefficient, skewness and kurtosis in sediments of Chongming Eastern Shoal, Hengsha Eastern Shoal and Jiuduan Shoal are of similar characteristics because there are closely positive correlated relationships among these parameters. However, due to the location difference between Nanhui Southern Shoal and Eastern Shoal, three parameters of grain size in sediments such as sorting coefficient, skewness and kurtosis have relatively large distinctions. Moreover, the tracks of sediment transport can be described based on the distribution of sediments which may reveal sediment transport controlled by the two dominant hydrodynamic factors of current and wave. It is appreciable that coarse sediments with better sorted is subjected to dominant ebb current action and intense wave action resulted from rapidly dissipated wave energy. In addition, due to the effects of obstructed branches, guided current and broken wave actions of the Deep Water Channel Project, grain size in sediments located on two sides of the groyne is of uneven distribution characteristics.

Key words: tidal flat sediments, particle sizes, current velocity, wave, Yangtze Estuar