广西钦江流域水沙年际变化规律分析

为了探究河流水沙的变化规律及影响因素,利用钦江陆屋流域1957—2016年的长时序年降水量、年径流量和年输沙率数据,采用5年滑动平均法、R/S检验法、Mann-Kendall突变检验法、累积距平法及复Morlet小波分析法分析以上序列的趋势性、突变性和周期性;运用双累积曲线法分析降水和径流输沙关系的变化;最后结合流域森林转型特征来进行分析。结果表明:(1)降水量弱上升、径流量减少、输沙率显著减少,在α=0.05和β=0.01的显著水平下,降水量和径流量无变异,输沙率弱变异。降水量在1962年、1971年、1989年和2013年发生突变,径流量在1963年、1971年、1989年和2007年发生突变,输沙率在1967年、1971年、1981年和2001年发生突变。降水量存在4类时间尺度,23 a、13 a分别为第一、二主周期;径流量序列存在3类时间尺度,14 a、9 a分别为第一、二主周期;输沙率序列存在4类时间尺度,22 a、5 a分别为第一、二主周期。(2)降水量-径流量累积关系分为两个阶段,即1957—1988年和1989—2016年,斜率分别为0.006 8、0.005 8;降水量-输沙量累积关系分为四个阶段:1957—1962年、1963—1988年、1989—1998年和1999—2016年,斜率分别为0.014、0.019 4、0.016 4、0.009,造成水沙关系变化的原因是人类活动的影响。(3)广西林业建设和森林转型的发展过程是径流量和输沙量不断发生变化的原因。

Analysis of interannual water-sediment variation law of Qinjiang River Basin in Guangxi

In order to explore the water-sediment variation law of river and its influence factors，the trend，multability and periodicity of the long time-series annual precipitation，annual runoff and annual sediment discharge from 1957 to 2016 of Luwu Watershed of Qinjiang River are analyzed herein in accordance with the data mentioned above by means of five-year moving average method，R/ S test method，Mann-Kendall test method，cumulative anomaly method and complex Morlet wavelet analysis method， and then the variation of the relationship between precipitation and the runoff-sediment transport is analyzed with the method of double mass-curve，and finally is analyzed in combination with the characteristics of forest transition within the watershed. The result shows that ( 1) The precipitation slightly increases along with the decrease of runoff and significant decrease of sediment transport rate. Under significant levels alpha = 0. 05 and beta = 0. 01，no any variations are there from the precipitation and runoff，but a slight variation is there from the sediment discharge. The precipitation abruptly changed in 1962，1971，1989 and 2013 and the runoff abruptly changed in 1963，1971，1989 and 2007，while the sediment discharge abruptly changed in 1967，1971，1981 and 2001 as well. Moreover，Four kinds of temporal scales are there for the precipitation with the first and second principal cycles of 23 a and 13 a respectively and three kinds of temporal scales are there for the runoff series with the first and second principal cycles of 14 a and 9 a respectively，while four kinds of temporal scales are there for the sediment dischargewith the first and second principal cycles of 22 a and 5 a respectively. ( 2) The precipitation-runoff cumulative relationship is divided into two phases， i. e. 1957—1988 and 1989—2016 with the gradients of 0. 006 8、0. 005 8 respectively and the precipitation-sediment cumulative relationship is divided into four phases，i. e. 1957—1962，1963—1988，1989—1998 and 1999—2016 with the gradients of 0. 014，0. 019 4，0. 016 4 and 0. 009 respectively. The causation of the variation of the water-sediment relationship is human activities. ( 3) The development processes of forestry construction and forest transition are the causes for the continuous variations of both the runoff and the sediment discharge in Guangxi.