山东省降雨侵蚀力与气候指数关系研究

Relationship Between Rainfall Erosivity in Shandong Province and Climate Indices

基于山东省18个气象台站1961—2010年的逐日降水资料,采用月降雨侵蚀力模型计算降雨侵蚀力,利用Mann-Kendall非参数检验法对近50 a来山东省降雨侵蚀力的时间变化趋势进行分析。运用皮尔逊相关系数、连续小波(CWT)、交叉小波变换(XWT)和小波相干谱(WTC)分析降雨侵蚀力与太平洋年代际涛动(PDO)、厄尔尼诺/南方涛动(ENSO)指数的相互关系和周期变化特征。结果表明,山东省年降雨侵蚀力呈下降趋势,特别是20世纪80年代以来,降雨侵蚀力下降趋势更为明显;分季节来看,除春季和冬季降雨侵蚀力呈增加趋势外,其他季节与年际变化趋势保持一致,呈下降趋势。月尺度上,7月降雨侵蚀力最大,12月最小,月际差异明显。山东省降雨侵蚀力与PDO和多元ENSO指数(MEI)的相关性存在明显的空间差异,与山东省降雨侵蚀力的负相关性从东南沿海向西北内陆逐渐递减。年际尺度上,山东省降雨侵蚀力存在0. 8~2 a尺度的年际振荡周期表现出与两大气候指数相似的变化特征。高能量区,山东省各区降雨侵蚀力与PDO和MEI指数的共振周期分别约为4~5和3~4 a。低能量区,山东省各区降雨侵蚀力与PDO显示出4 a左右的年际振荡周期,但显著性水平有所不同;降雨侵蚀力与MEI指数在不同时间段呈现出不同的共振周期。

Although water erosion is a key factor causing soil degradation,quantification of spatial and temporal variability in rainfall erosivity remains insufficient.Forced by the daily precipitation data from 18 meteorological stations,a monthly rainfall erosivity model was used to estimate the rainfall erosivity of Shandong Province from 1961 to 2010.Its temporal variation and trends were determined by means of Mann-Kendall trend test.Also,the relationship between rainfall erosivity and large-scale climatic oscillation were examined such as the Pacific decadal oscillation(PDO),nino/southern oscillation(ENSO)using the Pearson correlation coefficient,continuous wavelet transform(CWT),cross wavelet change(XWT)and wavelet coherence spectrum(WTC).The results show that annual rainfall erosivity experienced a downward trend during the past 50 years,especially since the 1980s.Summer and autumn rainfall erosivity exhibits the same trend with annual rainfall erosivity during the same periods,whereas upward trends occurs in the spring and winter rainfall erosivity.Seasonally,maximum rainfall erosivity occurs in July and minimum in December.The correlation between rainfall erosivity with the Pacific PDO and ENSO decreases from southeast coast to northwest inland.Rainfall erosivity of Shandong province reveals an approximately 0.8-2 year periodicity,which is similar to those for PDO and ENSO.In high energy area,the rainfall erosivity shows covariance with PDO and ENSO with periodicity of 4-5 years and 3-4 years,respectively.In low energy area,rainfall erosivity has a 4-year periodicity,which is same with PDO,but distinct from ENSO.These results are vital for soil and water conservation,and ecological restoration in Shandong Province.