关键词: 长江, 大通流量站, 输沙量, 时间序列分析, 河口

Abstract: The discharge of the water and sediment of the Yangtze River affect directly the evolvement of the Yangtze River delta,and even the change of material flux towards the sea. Datong station is the first interface in the Yangtze River estuary. There are nearly 50 years field data for the sediment and water discharge (1953~2001). In this paper, probability statistics and time series method such as Kendall method, order clustering method, Entropy spectral analysis were used to analyze the sediment discharge. The runoff discharge has been stable in Datong while sediment discharge has been declining obviously over the past 49 years. The change of sediment discharge decreases mainly in the form of jumping, taking on the rule of stepdown once every 16 years.In 1968 and 1984 the hopping site of step down was observed. The sediment discharge decreases greatly in Datong. After the hopping site (1984), the average sediment discharge per year decreases 26.4 % compared with the years before 1984, and even the maximum didn＇t exceed the average for years before 1984. The decline of sediment discharge is mainly related with activities of humanbeings. The main reason for sediment discharge decrease is the implementation of soil and water conservation along the Yangtze River since late 1980＇s with the effect of sediment trapping in the Yangtze drainage area.

Key words: the Yangtze River, Datong hydrometric station, sediment discharge, time series analysis, ｅstuary