雅砻江中上游径流变化特性的小波分析

根据雅砻江流域中上游雅江(1970~2004年)、洼里(1972~2004年)两水文站月径流资料,采用Db3小波函数分析径流特性和变化趋势.结果表明:雅江站径流总体呈增长趋势,但增长速度已经变缓;洼里站径流在1993年前呈稳定增长趋势,但在1993年后径流减少趋势越来越明显;而雅江-洼里区间径流量一直呈减少趋势.利用复Morlet小波通过连续小波变换分析径流的周期特性,并用小波方差识别主周期.结果表明:雅江站径流序列存在10~11 a的第一主周期和5 a左右、2~3 a的次主周期;洼里站径流序列存在9~10 a的第一主周期,5 a左右、2~3 a的次主周期和一个1 a左右的不明显周期.

Wavelet analysis of runoff variation characteristics in upper-middle reaches of Yalong River

Based on the monthly runoff series of the two hydrologic stations——Yajiang and Wali on the upper-middle reaches of Yalong River,the wavelet analysis method is adopted to analyze runoff variation characteristics of this watershed.That is to analyze the trend of runoff series with Db3 wavelet function;the result of which indicates that: at Yajiang station the runoff increases as a whole,but the increasing velocity has slowed down;while at Wali station the runoff had been increasing stably before 1993;but after then,it descended more and more;for Yajiang-Wali section,its runoff had been descending all the time.Continuous wavelet transform(CWT) is carried out to identify the periods of runoff series with complex Morlet wavelet,wavelet variance is employed to identify dominant periods.The results indicate that: there are 10 to 11 years' first dominant periods and approximate 5 years,2 to 3 years' sub-dominant periods at Yajiang station;and there are 9-10 years' first dominant periods,approximate 5 years,2-3 years' sub-dominant periods and an approximate 1 year's unobvious periods.