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本文运用Mann-Kendall统计检验、线性倾向估计和小波分析等方法对长江上游川江段气象水文要素的长期变化趋势及周期性进行了分析。研究表明:①川江段气温、径流呈不同程度的减少趋势,而降水则呈小幅度增加趋势,年变化率分别为气温-0.0017℃、降水0.3023mm、宜昌径流-6.6668m3/s、寸滩径流-9.5840m3/s,其中寸滩径流量减少趋势十分显著,通过了5%显著水平的信度检验;②川江段气温、降水、径流序列具有不同的周期成分,如年平均气温具有4年、8年和23年主周期,年降水具有3年、6年和16年主周期,寸滩站径流具有3年、8年和16年主周期,宜昌站径流具有3年、16年和45年主周期,且在时域分布上也是不均匀的;③另一方面,在气温略有降低、降水略有增加的气候组合下,川江段径流却呈现减小的变化趋势,同时川江段寸滩站和宜昌站的年径流量从20世纪90年代后期至今在变化特征上也表现出相反的趋势,这是因为人类活动所致还是气候变化影响所致,还有待深入研究。
In this paper, long-term trend and periodicity of meteorological and hydrological elements in the upper reaches of the Yangtze River are analyzed using Mann-Kendall statistical test, linear tendency estimation and wavelet analysis. The results showed that: (1) The temperature and runoff in the Chuanjiang section decreased with different degrees, while the precipitation showed a slight increase trend with annual rates of -0.0017 ℃, precipitation 0.3023mm, Yichang runoff -6.6668m3 / s, -9.5840m3 / s, of which the trend of decrease in runoff of Cuntan was very significant and passed the reliability test with a significant level of 5%. ② The temperature, precipitation and runoff sequences in the Chuanjiang section have different periodic compositions. For example, the average annual temperature has 4 years, 8-year and 23-year main cycles, annual precipitation with 3, 6 and 16 year main cycles, Cuntan station runoff with 3, 8 and 16 year main cycles, Yichang station runoff with 3, 16 and 45 years On the other hand, under the combination of climate with a slight decrease in temperature and a slight increase of precipitation, the runoff in the Chuanjiang section showed a decreasing trend. At the same time, The annual runoff of Yichang Station and Yichang Station also shows the opposite trend in the change characteristics since the late 1990s, which is due to the human activities or the impact of climate change, which needs further study.