鲁南地区降水量长期变化趋势对干旱的影响

Secular Variation Tendency of Precipitation and Droughts in South of Shandong

使用鲁南地区临沂(1951—2005年)、枣庄(1958—2005年)2个代表站逐月降水资料,利用累积距平及滑动t检验法、K-W检验法及SPI指数,分析鲁南地区降水量的长期变化趋势及干旱频率变化特征。结果表明:鲁南地区的年降水量于1970年代中期前后发生显著突变,突变后年降水量减少12%以上,其中汛期降水量减少16%以上,冬半年降水量变化趋势不显著。干旱年全部发生在年降水量突变后。对比鲁南地区降水量改变点前后气象干旱发生频率及持续时间发现,就干旱季节而言,临沂各季干旱频率均明显增大,枣庄春夏秋三季干旱频率明显增大;就干旱强度而言,各级干旱频率均明显增大,均以中度干旱频率增大最显著;就干旱持续时间而言,以持续3个月以上干旱频率增大最显著,干旱持续时间有明显延长趋势。

Based on the monthly precipitation date from 2 stations in the South of Shandong Province, the secular variation tendency of precipitation and the drought frequency are analyzed with the accumulated anomalous, skids the t-test and Kruskal-Wallis assay method. The results show that there is a evident decrease of the precipitation in the south of Shandong Province since 1950s, and a sudden change spot in the mid 1970s. After the chang spot, the precipitation reduced above 12%, especially in the rainy season, the precipitation reduced remarkably, above 16%. The dry season precipitation change was not remarkable. The droughts all happened after the sudden change spot. The dry season frequency and their intensities obviously increase since the sudden change spot. The frequencies of the 3- dry- month are high and the periods of continuous droughts are obviously long.