近60年长江中游宜昌站水沙变化与驱动因素分析

Analysis of Annual Runoff and Sediment Variation and Driving Factors at Yichang Station in Yangtze River over 60 Years

根据长江中游宜昌站1952~2015年长时间序列径流泥沙资料,运用Mann-Kendall趋势检验法、小波分析法和均值差异T检验等方法,揭示宜昌站径流泥沙的演变规律及其驱动因素。结果表明:(1)径流量无显著下降趋势,而输沙量下降趋势明显;(2)径流量在2005年发生突变,输沙量在2002年发生突变;(3)通过小波分析发现年径流量和年输沙量存在以20~24a为主周期的变化规律;(4)年径流量可分为1952~1955,1961~1968,1979~2001年3个多水期和1956~1960,1969~1978,2002~2015年3个少水期,输沙量可分为1952~1993,1998~2002年2个多沙期和1994~1997,2003~2015年2个少沙期;(5)年输沙量显著减少主要为水库拦沙、河道采砂和水土保持工程等人类活动所致。

According to the long-time series data of annual runoff and sediment at the Yichang Station in the Yangtze River during1952-2015, this paper revealed the evolution characteristics and driving factors based on Mann-Kendall, wavelet analysis and aver-age difference T methods. The results indicate that:(1) The annual runoff shows a slightly decreasing trend while the annual sedi-ment shows an obviously decreasing trend.(2) The runoff occurred mutation in 2005 while the sediment in 2002.(3) Wavelet anal-ysis demonstrates that the change characteristics of annual runoff and sediment show a main period from 20 to 24 years.(4) The annual runoff series can be divided into three high-flow periods(1952-1955, 1961-1968, 1979-2001) and three low-flow period(1956-1960, 1969-1978, 2002-2015) respectively. In addition, the annual sediment series can be divided into two high-sediment periods(1952-1993, 1998-2002) and two low-sediment periods(1994-1997, 2003-2015) respectively.(5) The significant reduction of the annual sediment are mainly resulted from sediment-trapping of reservoirs, sand mining on river channels, soil and water conservation projects.