近60年西江水沙时空演变特征分析

Spatial-temporal Change of Runoff and Sediment in Xijiang River Basin during The Last 60 Years

西江是珠江流域最大的河流,在滇、黔、桂、粤四省区经济社会发展中发挥着非常重要的作用。本研究基于22个水文站点的径流泥沙观测资料,对西江流域主要河流水沙变化的进行了分析。研究结果表明:(1)西江干流及其主要河流水沙年内分配高度集中在汛期,径流量占全年的比例在78.2%~81.9%,输沙量占全年的比例在95.9%~98.1%。(2)西江干流年平均径流量为2118.5×10~9m^3、平均输沙量为6187.7×10~4t,其径流主要来源于黔江、郁江和桂江,三者的贡献率达到87.8%,其泥沙主要来源于黔江和郁江,二者的贡献率达到91.3%。(3)近60年来西江干流、郁江年径流量呈现显著性减少的趋势;西江干流、郁江、黔江、桂江、红水河和北流河年输沙量呈现显著减少的趋势。(4)西江干流年径流量变化存在40~45年的主周期和25~28年的次周期,年输沙量变化存在20~23年的主周期,以及10~13年和4~6年的次周期。(5)在泥沙含量发生突变年份的前后时间段内,西江干流、黔江、郁江、红水河、刁江和北流江的挟沙能力明显增强,可侵蚀搬运的沉积物明显减少。西江流域水沙变化不仅与气候变化有关,而且还还与流域内生态工程建设和水利工程建设等人类活动密切相关。

Xijiang Rive is the largest river in Pearl river basin,it plays an important role for the economic and social development in Yunnan,Guizhou,Guangxi and Guangdong province. Based on the runoff and sediment data of 22 hydrological stations in Xijiang river basin,the spatial-temporal change of runoff and sediment are analyzed in this paper. Results indicate that the runoff and sediment mainly concentrate in flood period in mainstem and tributaries of Xijiang river,the proportion range of runoff and sediment in the flood period are 78. 1% to 81. 9% and 95. 9% to 98. 1%. The annual average runoff and sediment of Xijiang river mainstem are respectively 211. 85 billion cubic meters and 61. 877 million tons,the runoff mainly come from Qianjiang river,Yujiang river and Guijiang river,which have contributed the 87. 8 %of total annual runoff,and the sediment is mainly from Qianjiang river and Yujiang river,which have contributed the 91. 3% of total sediment in Xijiang river mainstem. During the past 60 years,the annual runoff shows a significant decreasing trend in Xijiang river mainstem and Yujiang river,and the annualsediment yield also exhibits a significant decreasing trend in Xijiang river mainstem,Yujiang river,Qianjiang river,Guijiang river,Hongshui river and Beiliu river. The annual runoff shows periodic variations with the main periods being 40 to 45 years and the secondary period of about 25-28 years,and the annual sediment with the main periods being 20 to 23 years and the secondary period of about 10-13 years and 4-6 years. There were periodic variations with the main Dcriods being 9 to 1 0 years and the secondary period of about 3 years.Before and after the mutation of sediment concentration,there present a significant increase in the sediment-carrying capacity and a significant decrease in the eroded sediments in Xijiang river mainstem,Yujiang river,Qianjiang river,Diaojiang river,Hongshui river and Beiliu river.The change of runoff-sediment relationship is affected not only by the climate change,but also by the construction of ecological conservation projects and water conservancy project.