近60年广西西江流域年输沙模数特性分析

Characteristic Analysis of Annual Sediment Transport Modulus of Xijiang River Basin in Guangxi over Last 60 Years

利用Mann-Kendall秩次相关检验、Spearman秩次相关检验和Mann-Whitney-Pettitt突变点分析研究西江流域年输沙模数的趋势和突变成分;利用Kriging插值法对年输沙模数的均值和趋势等进行空间插值;绘制双累积曲线和利用水文分析法研究年输沙模数的变化成因。结果表明:西江流域年均输沙模数在20世纪60—70年代上升,但在80年代又持续下降;多年输沙模数20世纪60年代从西部和东部到东北部逐步减小,70年代从外部到中部逐步减小,80年代从西北部和东部到南部和东北部逐步减小,90年代从西北部和东部到中部和东北部逐步减小,2000—2009年从东部和西部向北部逐步减小;一般情况下上游多年平均输沙模数大于中下游的多年平均输沙模数;在不受降水变化影响的情况下,西江年输沙模数的变化主要是人类活动影响流域侵蚀产沙的结果,降水变化对输沙模数的贡献率为6.3%~12.3%,人类活动的贡献率为87.7%~93.7%。

Mann-Kendall rank correlation test, Spearman rank correlation test and Mann-Whitney-Pettitt abrupt change point analysis were performed to study the trend and mutation components of the annual sediment transport modulus of the Xijiang River Basin.Then, the kriging interpolation method was used for spatial interpolation in the mean and trend of the annual sediment transport modulus.After a double cumulative curve was drawn, the hydrological analysis method was employed to examine the causes of the changes in the annual sediment transport modulus.The results show that the average annual sediment transport modulus of the Xijiang River Basin increased in the 1960 s—1970 s but kept decreasing in the 1980 s.The multi-year sediment transport modulus drops gradually from west and east to northeast in the 1960 s, from outer to central in the 1970 s, from northwest and east to south and northeast in the 1980 s, from northwest and east to central and northeast in the 1990 s, and from east and west to north in 2000—2009.In general, the multi-year average sediment transport modulus of the upper reaches is greater than that of the middle and lower reaches.Without the influence of precipitation change, the variation of the annual sediment transport modulus of the Xijiang River mainly results from human activities affecting the erosion and sediment yield of the basin.The contribution rate of precipitation change to the sediment transport modulus is 6.3%~12.3%,whereas that of human activities is 87.7%~93.7%.