沱江上游径流周期性与季节影响分析

依据沱江上游三皇庙水文站近50 a的流量资料，采用小波分析方法对多年月径流量与各年汛期流量进行多时间尺度的周期性分析和突变点检验。通过小波方差图得到各序列变化的主周期；尝试应用X-11季节调整方法对月流量序列进行季节因子提取，分析得到月径流量的多年变化走势和季节影响特点。结果表明：月流量存在3个突出的主周期，分别为1~2,11,21 a，此外还有3 a和5 a两个不明显周期；汛期流量则表现明显为3,5,13 a的3个主周期；每年的汛期月流量季节因子影响明显高于整体水平，受季节因素影响显著，其中7月份季节影响因子呈逐年增大，年际变化平稳，8,9月季节影响因子年际变化剧烈。

Periodic and Seasonal Impact of Runoff in the Upstream of Tuojiang River

Based on runoff series in the past 50 years measured at Sanhuangmiao hydrologic station in the upstream of Tuojiang River,we adopted wavelet analysis to analyze the monthly runoff over years and the flood season flow in each year to find out the catastrophe points and period characteristics at multi-time scales.Wavelet variogram was used to identify dominant periods,and X-11 seasonal adjustment method was applied to extract the seasonal factors from monthly runoff series in order to obtain the trend and the seasonal impact.Results indicated that: the monthly runoff series exhibited three dominant periods of 1-2 years,11 years,and 21 years and two sub-dominant periods of 3 years and 5 years,while the flood season flow was featured by three obvious dominant periods of 3 years,5 years,and 13 years.The impact of seasonal factors on monthly runoff in flood seasons were higher than that in other months.The seasonal factors in July increased steadily by years,and changed remarkably in August and September.Researches on runoff change would contribute to the exploitation of water resources and the optimal scheduling of water resources in canal irrigation areas.