1971—2010年中国干湿区降雨资源变化特征分析

降雨在农业生产领域、科学技术领域以及预报洪涝灾害、分析水资源等方面意义重大。利用全国1971—2010年743个气象站点的逐日降雨数据,基于干旱区、半干旱区、半湿润区和湿润区的干湿区划分,对年降雨量和年降雨日数按等级进行划分,运用线性倾向率、累积距平、M-K检验和滑动t检验等方法系统分析了4个干湿区内不同等级年降雨量和年降雨日数变化特征以及各区域年降雨量时间演变特征。结果表明:①过去40 a各干湿区年降雨日数分布存在差异,其中湿润区年降雨日数呈中部高、周边偏低分布趋势;②干旱区北部小雨的降雨贡献率和频率较高,半干旱区大到暴雨的降雨贡献率和频率低下;③在年代际变化中,1991—2000年湿润区年降雨量增加幅度最大,2001—2010年半湿润区年降雨量变化不明显;④各干湿分区的年降雨量近40 a突变趋势不一致,湿润区在2002年发生从多到少突变,而半干旱区未发生突变。研究成果对于预测旱涝灾害、分析水资源及治理生态环境等方面具有参考价值。

Characteristics of Rainfall Amount Variations in Wet and Dry Partitions of China from 1971 to 2010

According to daily rainfall data at 743 meteorological stations from 1971 to 2010, we classified annual rainfall amount and rainfall days by grade and further discussed the variation characteristics of rainfall amount and rainfall days and the temporal evolution of annual rainfall in four regions (arid region, semi-arid region, semi-humid region and humid region) via linear trend analysis, accumulative anomaly, M-K test and moving-t test. Results demonstrated that (1) in the past four decades, the annual rainfall days differed among the four regions, among which the humid area experienced more days of rainfall in the middle but less in the surroundings. (2) In the north part of arid region, light rainfall contributed more with high frequency, whereas in semi-arid regions, heavy rain and rainstorm contributed less with lower frequency. (3) In terms of interdecadal change, the annual rainfall amount during 1991-2000 increased most remarkably in humid region, yet not obviously in 2001-2010 in semi-humid region. (4) The trend of abrupt change of rainfall amount was inconsistent between wet and dry regions: in humid region the rainfall amount declined abruptly in 2002, while in semi-arid region no abrupt change happened.