RECENT CHANGES IN RUNOFF AND SEDIMENT LOAD AND THEIR TENDENCY IN THE UPPER CHANGJIANG RIVER

摘要

This paper statistically analyse the runoff and sediment load changes at the major stations in the Upper Changjiang River. Compared with the annual runoff and sediment load before 1990, there were three major changes of annual sediment load in the period of 1991-2002; the annual decrement was about 0.13 x 10~9t at Yichang Station; the annual increment was about 0.035 x 10~9t at Pingshan Station and the percentage (accounted by Yichang station) also increased from 51.8% to 71.9%; the annual decrement was about 0.0985 x 10~9t at Beibei Station and the percentage also decreased from 25.7% to 9.1%. Based on the analysis of several non-parameter statistical methods such as moving average check and Spearman order correlativity check, the paper concludes that the runoff changing tendency at Pingshan Station is not distinct, but the sediment load increasing tendency is distinct; the runoff and sediment load at Beibei Station decreased tendency aer very distinct; the runoff changing tendency at Yichang Station is not distinct, whereas the sediment load increasing tendency is distinct.