秦巴山区降雨侵蚀力时空变化特征

Spatiotemporal Variation of Rainfall Erosivity in Qin-Ba Mountains Region

降雨侵蚀力时空变化特征的研究对区域土壤侵蚀风险评估及水土保持规划具有重要的意义。利用秦巴山区及周边地区共63个气象站1961～2016年的逐日降雨量数据计算各站的降雨侵蚀力,借助Kriging空间插值法、Mann-Kendall趋势检验、Pettitt突变检验等方法分析了秦巴山区降雨侵蚀力的时空变化特征。结果表明:秦巴山区年均降雨侵蚀力为3 696 MJ·mm/(hm^2·h·a),年内变化呈单峰型,7月最大,占全年的26. 6%;四季中,夏季最大,冬季最小。代际间,20世纪80年代的降雨侵蚀力最大,90年代最小。年际间,年降雨侵蚀力存在明显的阶段性,但未表现出显著的趋势性和突变性特征。秦巴山区多年平均降雨侵蚀力呈南高北低的分布格局,不同地区年均降雨侵蚀力变化于787～8 858 MJ·mm/(hm^2·h·a)之间;整体而言,年降雨侵蚀力随纬度增加而减小,随海拔升高而减小。

The investigation of the spatiotemporal heterogeneity of rainfall erosivity is significant in regional soil erosion risk assessment as well as water and soil conservation planning. Based on long-period( 1961-2016) daily rainfall data from 63 meteorological stations located in Qin-Ba mountains region and its surrounding area,this study calculated values of rainfall erosivity and analyzed the spatial and temporal variation of rainfall erosivity using Kriging spatial interpolation method,Mann-kendall trend test,Pettitt test and other methods. Results showed that the regional average annual rainfall erosivity was 3 696 MJ · mm/( hm^2· h · a). The rainfall erosivity showed a unimodal intra-annual variation with a maximum value in July accounting for 26. 6 % of the total year and also had a strong seasonal pattern with maximum rainfall erosivity in summer and minimum in winter. The rainfall erosivity reached its maximum in the 1980 s and minimum in the 1990 s. The annual rainfall erosivity had distinct phases,whereas had no significant trends and mutations. It turned out that the spatial distribution of the average annual rainfall erosivity in the region increased from north to south varying from 787 to8 858 MJ·mm/( hm^2·h·a). Furthermore,the average annual rainfall erosivity of Qin-Ba mountains region generally decreased with the increasing of latitude( P<0. 01) and altitude( P<0. 01).