Analysis of recent changing characteristics and tendency runoff and sediment transport in the upper reach of Yangtze River

This paper statistically analyses the runoff and sediment transport of the major stations in the upper reaches of Yangtze River. Compared with the annual runoff and sediment transport before 1990,there were three major changes of annual sediment transport in the term of 1991-2002:the Yichang station decreased about 1.3×10⁸t;the Pingshan station at the Jinsha River increased about 0.35×10⁸t,and the percentage(compared with Yichang station)also increased from 51.8% to 71.9%;and the Beibei station increased about 0.985×10⁸t,and the percentage also decreased from 25.7% to 9.1%. Through several non-parameter statistical methods such as the moving average check,the Spearman order correlativity check and the linear regression check,the paper concludes that the trend of runoff evolvement at the Pingshan station is not distinct, and nor is that of the sediment transport increased;but trends of the runoff and sediment transport decreased are very distinct; the trend of runoff evolvement at the Yichang station is not distinct,and the trend of sediment transport increased is distinct. The major factors correlated with the runoff and sediment transport changes such as the rainfall,water-and-soil conservation measures,reservoir trap and artificial inducements of soil etc. are also introduced.