近45年来浏阳河流域极端降水变化

Change in Extreme Precipitation in Liuyang River Basin During the Past 45 Years

利用1969—2013年浏阳河流域12个雨量站的降水资料,结合百分位方法定义极端降水阈值,采用线性回归、滑动平均、Mann-Kendall检验、累积距平联合滑动t检验和Morlet小波分析等方法分析了极端降水指数的演变规律。结果表明:(1)极端降水量、极端降水强度、极端降水比率表现为上升趋势,10年上升率分别为7.3mm,9.5mm/d,0.3%,极端降水日数表现为下降趋势,下降率为-0.054d/10a。(2)极端降水量、极端降水强度分别在1991年、1992年存在明显突变,极端降水日数、极端降水比率突变不显著。(3)极端降水指数均存在7~8a,10~11a和25~27a的主周期,且丰枯交替变化明显。研究结果对于指导浏阳河流域的防洪减灾具有重要意义。

Based on daily precipitation data from 12 weather stations in Liuyang River Basin during the period of 1969—2013 and the percentile-based threshold method,the extreme precipitation indices were analyzed by using linear regression,moving average,Mann-Kendall test,accumulative anomaly combined with moving t test and Morlet wavelet.The results indicated that:(1)extreme precipitation,precipitation intensity and precipitation ratio displayed increasing trends at the rates of 7.3 mm/decade,9.5 mm/d and 0.3%,respectively,while the number of extreme precipitation days represented a decreasing trend at the rate of -0.054d/decade;(2)abrupt changes in the extreme precipitation and precipitation intensity were detected in 1991 and 1992,respectively,while the number of extreme precipitation days and the ratio of extreme precipitation ratio to the total precipitation amounts were not statistically significant;(3)the extreme precipitation indices had the main oscillation cycles of 7~8 years,10~11 years and 25~27 years,respectively,together with clear alternation between dry and wet years.The results are of great importance in flood control and disaster reduction in Liuyang River Basin.