1960—2012年长江中下游极端降水与极端径流时空演变研究

利用1960—2012年间的长江中下游地区75个站点的逐日降水观测资料,基于11个极端降水指标,采用趋势分析、滑动平均、Mann-Kendall检验等方法对长江中下游地区各个子流域的极端降水事件的时空变化以及极端降水的集中度和集中期进行了研究.同时,分析了长江中下游干流区域4个水文站点的极端径流的变化情况,以期综合全面地分析极端事件的演变情况.结果表明:1)极端降水在各个子流域的大部分地区都表现为增加趋势,其中汉江流域西北部、中游干流区域东部、洞庭湖西部、鄱阳湖北部以及下游干流东北部显著增加;2)极端降水在总降水量中所占比例较大,这表明降水的形式更加趋于集聚化,并且比例自西北向东南逐渐减少,这表明越往西北部极端降水造成灾害的概率越大;3)长江中下游干流区域几个主要水文站点的极端径流各项指标均表现为较为显著地减小的趋势,极端降水和极端径流的变化趋势差异较大,这可能与人类活动有关(三峡工程).

Research on Spatio-temporal Variation of Extreme Precipitation and Extreme Run off in the Middle and Lower Reaches of Yangtze River from 1960—2010

Using the daily precipitation data of 75 stations in the middle and lower reaches of Yangtze River from 1960 to 2012. Based on 11 extreme precipitation indices, the temporal and spatial characteristics as well as the precipitation concentration degree and con-centration period of extreme precipitation events are studied by means of trend analysis, sliding average and Mann-Kendall test. At the same time, the extreme runoff variations of 4 stations in the middle and lower reaches of the Yangtze River are discussed, so as to analyze the evolution of extreme events comprehensively. Our results show that: (1) The extreme precipitation events in most areas showed an increasing trend, especially the northwest of Hanjiang River Basin, the east of middle Yangtze River, the west of Dongting Lake, the north of Poyang Lake and the northeast of lower reach of Yangtze River;(2) The extreme precipitation accounts for a large proportion of total precipitation, which indicates that the form of precipitation tends to be more agglomeration. In addition, the ratio gradually decreases from northwest to southeast, which also indicates that extreme precipitation in the northwest is more likely to cause disaster;(3) The extreme runoff indices of the main stations in several regions of the middle and lower Yangtze River show obvious decreased trend, the trend of extreme precipitation and extreme runoff are large, this may be related to human activities ( Three Gorges Project) .