1951-2015年洞庭湖水沙变化特征分析

Analysis of characteristics of annual runoff and sediment in Dongting Lake during 1951-2015

基于洞庭湖入湖(湖南四水、荆江三口)和出湖(城陵矶)的主要控制性水文站1951-2015年实测水沙数据,运用5a滑动平均法、M-K非参数检验法、小波分析法等,对洞庭湖进出湖水沙变化的趋势性、突变点、周期性进行分析.结果表明:1)洞庭湖水沙均呈现出下降趋势,其中以荆江三口中的藕池口输沙量下降趋势最为显著,以217.9万t/a的速度衰减,其次为城陵矶输沙量,以84.934万t/a的速度衰减;2)除湖南四水径流量未发生突变外,洞庭湖水沙序列均发生了突变;3)湘资沅澧四水径流量第1主周期分别为35、23、35、23a,输沙量分别为35、20、35、20a;荆江三口松滋口、太平口、藕池口径流量第1主周期分别为25、27、17a,输沙量分别为27、30、15a;城陵矶径流量第1主周期为33a、输沙量为23a.

Based on the measured data of runoff and sediment from 1951 to 2015 of the main controlled hydrological stations in the Dongting Lake(the Four Rivers in Hunan Province,Three Outlets of Jingjiang River)and out of the lake(Chenglingji),we analyzed the trend,abrupt change points and periodicity of runoff sediment in and out of the Dongting Lake’s characteristics by the 5 amoving average method,Mannkendall(M-K)Nonparametric test method and wavelet analysis method.The results show:1)The annual runoff and sediment discharge of Dongting Lake showed a downward trend;among them,the sediment discharge of Ouchi Lake in the Three Outlets of Jingjiang River was the most significant,with the rate of2.17 9×106 t/a decreasing,followed by the sediment discharge of Chenglingji with the speed of 8.493 4×105 t/a.2)The annual runoff and sediment at the Dongting Lake has been mutated,in addition to the runoff along the Four Rivers no mutations occurred.3)The first main cycle of the Xiangjiang River,Zishui River,Yuanjiang River,Lishui River’s runoff was respectively 35,23,35,23 aand sediment’s was 35,20,35 and 20 a;the runoff of the three outlet was respectively 25,27 and 17 aand the sediment was 27,30 and 15 a;the first main cycle of runoff in Chenglingji was 33 a,sediment discharge was 23 a.