变化环境下西江下游高要段水沙变化及原因分析

Variation Characteristics and Influencing Factor of Runoff and Sediment in the Gaoyao Reaches of Xijiang River under Changing Environment

利用累积距平法和累积双曲线法,对西江下游梧州水文站及高要水文站1974—2018年年径流量和年输沙量的变化趋势进行分析对比,探究在人类活动影响下西江下游高要段水沙变化特征。结果表明:在排除降水因素的影响后,梧州水文站与高要水文站年径流量变化具有一致性,表明高要水文站径流变化主要受到梧州水文站上游水利工程投产运行的影响。1974—2018年高要水文站年输沙量的突变点出现在1998年,1998年以后,输沙量呈下降的趋势,这与上游水利工程蓄水截沙及水土保持等因素有一定关系;梧州水文站1974—2018年年输沙量的突变点出现在1993年,1993年以后,输沙量呈下降的趋势;1993—1998年高要水文站年输沙量仍呈现增长趋势,这与以罗定江流域为代表的区间水土流失有关;随着梧州水文站上游水电站的陆续建成,1992年岩滩水电站投入运行,2006年龙滩水利枢纽投入运行,流域水利工程累积库容也随之增加,对泥沙的拦截量同时增加,流域输沙量呈减少的趋势。

The variation trends of annual runoff and annual sediment transport of Wuzhou Hydrological Station and Gaoyao Hydrological Station in the lower reaches of Xijiang River from 1974 to 2018 are analyzed and compared by using the cumulative anomaly method and cumulative hyperbola method,so as to explore the variation characteristics of water and sediment in the Gaoyao section of the lower reaches of Xijiang River under the changing environment.The results show that:After excluding the influence of rainfall factors,the annual runoff of Wuzhou hydrology station and Gaoyao hydrology station are consistent.This shows that the change of flow rate of Gaoyao hydrology station is affected by the operation of upstream water conservancy project of Wuzhou hydrology station.The abrupt change point of annual sediment transport from 1974 to 2018 in Gaoyao hydrology station was in 1998.After 1998,the sediment transport showed a downward trend.The abrupt change of annual sediment transport from 1974 to 2018 in Wuzhou hydrology station occurred in 1993.After 1993,the sediment transport showed a downward trend.From 1993 to 1998,the annual sediment transport volume of gaoyao hydrology station still showed an increasing trend,which was related to soil erosion in the region represented by Luoding river basin.With the increase of hydropower stations above the section of Wuzhou hydrology station,Yantan hydropower station was put into operation in 1992,and Longtan hydropower station was put into operation in 2006,the accumulative storage capacity of water conservancy projects in the basin also increased,and the sediment interception increased at the same time.Under the combined action of water conservancy project and soil and water conservation measures,from 1999 to 2018,the sediment transport capacity of Gaoyao hydrology station showed a decreasing trend.