长江大通站水沙年际变化分析

Analysis of Water and Sediment Variation of Datong Station

本文首先基于长江大通水文站径流量、输沙量等实测资料，采用传统分析法和时间序列法等方法，对大通站水沙时间序列进行年内分配变化和年际变化分析并进行了趋势预测。研究结果表明：（1）年径流量略有下降趋势：在1955年、1988年、2003年发生上升或下降突变；年径流量呈明显丰枯交替现象，存在32a、20a、6a尺度的周期变化．在32a尺度上的振荡最为强烈。（2）年输沙量呈明显下降趋势；在1969年，1987年，2003年呈连续阶段性下降：存在20a、10a、6a的周期变化，其中20a为全时域周期振荡。（3）水沙变化趋势预测：径流量将进入一个20a左右的枯水期，在8-10a内将呈下降趋势；目前输沙量在10a内都将位于一个少沙周期，且在4—5a内都将呈下降趋势。

Based on the measured data of runoff and sediment of Datong hydrological station, the traditional methods and time series method have been used to analyse the interannual and annua distribution variations of the time series of runoff and sediment of Datong station. The rule of fluvial processes is studied related to the analysis results. Then the article forecast the tendency of riverbed evolution. The result shows： （1）The runoff process is stably and slightly decreasing, with slightly mutations in 1955, 1988 and 2003. The runoff series shows a wet-dry alternate phenomenon, and has 32a, 20a, and 6a periodic oscillations, which oscillate the most obviously in 32a. （2）The trend of sediment process is obviously decreasing stage by stage in 1987, 1969 and 2003. The sediment series has 20a, 10a, 6aperiodic oscillations, and the 20a periodic oscillation is full time-domain.（3）The variation tendency of runoff and sediment is as： runoff series are about to enter a low water period and will keep decreasing in 8-10a. The sediment series are in a low discharge period, and will keep decreasing in 4-5a.