三江源区近数十年河流输沙及水沙关系变化

Variations of riverine sediment and the relationship between runoff and sediment in the source region of three rivers

河川径流及泥沙在保障水资源、塑造河道形态、维持区域环境及生态系统等方面起着重要作用。为探讨三江源区河流输沙及水沙关系,基于三江源区9个水文站径流泥沙观测资料,采用Mann-Kendall趋势检验、Mann-Kendall突变检验方法分析输沙量、含沙量的变化趋势及突变特征,利用评级曲线法,分析水沙关系。结果表明:1)从输沙量来看,仅长江源区的新寨输沙量呈显著减少趋势,并在1998年发生突变;2)长江源区新寨含沙量显著减少,黄河源区的黄河沿、同仁及唐乃亥含沙量显著增加,其他水文站含沙量没有显著变化趋势,新寨和同仁含沙量分别在1999和1989年存在突变特征;3)直门达以上的长江源区及澜沧江源区水沙关系未发生明显变化,长江源区的新寨水文站控制区及黄河源区水沙关系发生变化;4)水流挟沙能力的变化表现出了明显的空间差异性,主要分为减弱、增强及稳定3种类型。河流输沙及水沙关系发生的变化,可能与气候变化和人类活动等有关,研究成果可为三江源区流域规划和生态保护,以及下游水库泥沙淤积研究等提供参考。

[Background] Runoff and sediment play an important role in the supply of water resources,shaping the river morphology,maintaining the regional environmental and ecological system. [Methods]To explore the characteristics of river sediment and the relationship between runoff and sediment in the source region of 3 rivers（ the Yangtze River,the Yellow River,and the Lancang River）,based on observation data of runoff and sediment at 9 hydrologic stations in the source region of 3 rivers,the change trends and change-point of sediment discharge and sediment concentration were analyzed using the Mann-Kendall trend test,Mann-Kendall change-point test methods,and the relationship between runoff and sediment was analyzed using the rating curve method. [Results]1） There were no significant change trend and change-point of annual sediment discharge in Zhimenda hydrologic station in the source region of the Yangtze River,Tangnaihai and Tongren hydrologic stations in the source region of the Yellow River,and Xiangda hydrologic station in the source region of the Lancang River,while the trend of annual sediment discharge in Xinzhai hydrologic station（ Batang River） in the source region of theYangtze River was reduced significantly and changed greatly in 1998. 2） The annual sediment concentration, in Xinzhai hydrologic station, in the source region of the Yangtze River, reduced significantly,while it increased conspicuously in Huangheyan, Tongren and Tangnaihai hydrologic stations in the source region of the Yellow River,and the sediment concentration did not change apparently in other 5 hydrologic stations. A change-point of sediment concentration existed in Xinzhai hydrologic station of Batang River,in 1999,and in Tongren hydrologic station of Longwu River,in1989. Exactly,sediment discharge in Xinzhai hydrologic station had presented a downward trend since1999 and contrarily an upward trend in Tongren hydrologic station since 1989. 3） Relationship between runoff and sediment did not change obviously in watershed in the source region of Yangtze River controlled by Zhimenda hydrologic station and in which,in source region of Lancang River,controlled by Xiangda hydrologic station. Adversely,the relationship varied obviously in Xinzhai control area in the source region of the Yangtze River and control areas in the source region of the Yellow River. Meanwhile,the relationship between runoff and sediment in Huangheyan hydrologic station control area changed stupendously due to adjustments stem from lakes. 4） The change of the capacity of water-carrying sediment showed an obvious distribution of spatial heterogeneity, mainly divided into three types,including weakening,enhancing and stabilizing. [Conclusions]Heterogeneity of sediment transport and relationship between water and sediment were revealed in the source region of 3 rivers,which may be concerned with climate change and human activities. The above research achievements can be useful reference to plans and ecological conservations in this region and research concerning sediment concentration in reservoirs of its lower reaches.