长江源区水沙变化特征及成因分析

Processes of runoff and sediment load in the source regions of the Yangtze River

基于3个水文控制站的历史资料和6个国家级气象站点的同期气象资料,采用Mann-Kendall趋势分析和双累计曲线等方法,揭示了长江源区不同时间尺度下的水沙演变特征,定量评估了水沙变化的主要影响因素。结果表明:1956-2017年长江源区径流量呈现出显著增加趋势,尤其是21世纪以来径流量增加最为明显。空间分布显示,沱沱河以上地区径流量增加更为显著,尤其是夏、秋两季径流量增幅最大。输沙量年际波动较大,变化趋势呈现出明显的区域差异和季节差异。沱沱河站和新寨站输沙量变化趋势分别为32.73万t/10a和-2.05万t/10a(p<0.01),均以夏秋两季的变化幅度最大。直门达以上地区输沙量总体变化趋势不明显。水沙年内分配呈现出明显的不均匀性,沱沱河站水沙年际变化较直门达站剧烈。气候变化对长江源区径流增加的贡献率为91%,人类活动等因素对输沙量变化的贡献率为80%。

Based on the historical data of three hydrologic stations and climate data of six national meteorological stations,the processes of runoff and sediment load,as well as its influence factors were studied in the source regions of the Yangtze River by Mann-Kendall test and double mass curve.Results show that runoff in Tuotuohe and Zhimenda station increased significantly with a rate of 93 and 448 million m3/decade during 1956-2017,especially since the 21st century.Geographically,the increasing trends is more notable in Tuotuo river area.Significant upward and downward trends were observed in Tuotuohe and Xinzhai station,respectively.Generally,there was no significant trend during the past 62 years in the source region of the Yangtze River.Climate change causes a greater influence on runoff,while sediment was mainly affected by human activities.