嫩江流域径流量多时间尺度特征分析

目前在全球气候变化与人类活动的双重影响下,陆地水文循环发生了深刻的变化,近50年来,嫩江流域径流过程发生了巨大变化,加剧了水资源的短缺和时空变异性,并带来一系列突出的水与生态环境问题.本文根据嫩江、石灰窑、同盟、江桥、大赉水文站1956年～2006年51a的径流资料,采用Morlet小波对嫩江流域径流序列进行了多时间尺度研究,结果表明:流域径流演变过程存在明显的多时间尺度特征,具有8a、20a、45a多尺度的周期变化规律,且以45a尺度的年代周期信号最强,表明45a尺度的年代周期变化最为明显;嫩江、江桥气象站的降水周期与上述径流资料基本一致,说明降水的变化是流域径流演变过程的重要自然控制因素.

Discussion on Multiple Time Scales of Runoff Variation in the Nenjiang River Basin

The Nenjiang River is one of the most important rivers in the northeast of China. In the past 50 years, global climate change and the increasing density of human activities have greatly changed the water cycle and induced a series of environmental problems. The runoff and precipitation variations in the Nenjiang River Basin are studied in order to contribute to the rational and scientific management of water resource. Shihuiyao station on the upper stream, Tongmeng station on the middle stream as well as Jiangqiao and Da lai stations on the lower reaches of the Nenjiang River are selected in the paper. Based on the runoff data observed in 1956~2006 by hydrological stations in the Nenjiang River Basin, the characteristics of the multiple time scales and driving forces of annual runoff are studied by using wavelet analysis and other mathematical methods. The results show that there are obvious multiple time scales in the annual runoff variation process. The long-term cycle of runoff time-series in Nenjiang is about 45 years, with the strong energy and it is the most obvious. The other long-term time-series cycle is about 20 years, with a smaller energy. The short-term cycle of runoff time series in Nenjiang is about 5 to 8 years. The 45 years can be divided into three periods: from 1956 to 1968, Nenjiang River was in high water period; from 1968 to 1981 it was in low water period; and from 1981 to 1996 it was in high water period again. At present, Nenjiang River is in low water period. It is predicted that it will turn to high water period in the year 2010. The wavelet analysis of the precipitation data from Nenjiang and Qiqihar station shows that: the precipitation cycle is similar to the runoff cycle in the Nenjiang River Basin. The long-term cycles of the time series are also 45 and 20 years respectively, while the short-term cycle of precipitation time series is also about 5 to 8 years. And the 45 years and 5 to 8 years pattern is more obvious with the strong energy. Its changing pattern in the 45 years and its present status are the same with that in the runoff variation process. It can be concluded that the variation process of annual runoff is mainly influenced by the precipitation, and the variation cycles of runoff and precipitation are consistent.