西江干流径流年际及年内变化趋势分析

Study on interannual and annual variation characteristics of runoff in the main stream of Xijiang River

为了分析西江干流径流年际变化趋势及年内分配规律,根据天峨、迁江、梧州三站60多年实测径流资料,采用Mann-Kendall趋势检验法、R/S法、有序聚类法、滑动T检验法等多方法分别对径流年际变化的趋势性和突变性进行分析;同时,对表征径流年内分配的各指标进行趋势性检验和未来变化趋势预测。结果表明:三站的M-K统计量Z值分别为-2.47、-2.38和-1.47,Hurst指数分别为0.72、0.83和0.80,均大于0.5;天峨站和迁江站的突变点均为2002年,梧州站的突变点为1954年和2002年;西江径流60多年来显著减少,且具较强的持续性;径流年内分配不均,多集中在4月-9月,占年径流的75%左右;2002年后径流年内分配显著性地趋于均匀,集中程度和变幅亦显著性地变小,集中期前移12日左右。

In order to study the interannual variation trend and annual distribution of runoff in Xijiang River,we used Mann-Kendall trend test,R/S method,ordered cluster method,and sliding T test to analyze the variation trend and abrupt changes of interannual runoff,and we conducted trend tests and prediction of the future change trend for each index of annual runoff distribution.The analysis was based on the measured runoff data of the main stream of Xijiang River for over 60 years.The results showed that M-K statistic values in the three stations were -2.47,-2.38 and -1.47 respectively.The Hurst indexes of the three stations were 0.72,0.83 and 0.80 respectively,all greater than 0.5.The abrupt change points at Tian＇e and Qianjiang stations were both in 2002,while the abrupt change points at Wuzhou station were in 1954 and 2002.Xijiang River runoff has significantly declined over the past 60 years with a strong continuity.The annual distribution of runoff was uneven.The runoff concentrated during April to September,which accounted for about 75% of the annual runoff.After 2002,the annual distribution of runoff showed a remarkable tendency towards uniformity; the degree of concentration and variation amplitude both significantly decreased,and the concentration period moved about 12 days forward.