基于SPEI的贵州省分区干旱时空演变特征

[目的]干旱对贵州省水循环及水资源管理系统造成严重破坏,科学合理地认识干旱时空演变对抗旱减灾及社会稳定至关重要。[方法]利用贵州省18个气象站点1960 2012年逐月降水和平均气温数据计算标准化降水蒸散指数SPEI评估干旱,采用M-K趋势检验、B-G分割法、极点对称模态分解法ESMD和反距离权重插值法分析了贵州省分区分时段干旱时空演变特征。[结果]贵州省月、季和年尺度SPEI序列均呈波动下降趋势,其中夏季和冬季SPEI序列变化未通过显著性检验,且20世纪60 90年代,贵州省各分区干湿变化具有较强的一致性,21世纪各分区的干湿变化不具有明显的一致性;以黔西北年SPEI为例,基于ESMD分解法得到3个模态分量IMF和1个趋势项R,从R看出干旱指数整体上呈波动“减小-增大”趋势,分析IMF1-IMF3振荡可得黔西北地区干旱具有2.1、7.6和26.5a的周期特征,且年代际周期26.5a在干旱变化中起主导作用,ESMD法在非线性、非平稳时间序列周期及趋势分析中应用效果较好;依据B-G分割法检测结果,得到1960 1986年、1987 2003年和2004 2012年3个研究时段,2004 2012年黔西北地区的冬旱强度和黔西南地区的春旱频率达到最大,分别为1.82和77.78%,2004 2012年四季干旱强度明显增大,且1986 2012年贵州省高强度干旱呈现由北向南转移趋势,1960 2003年四季干旱高频区呈现由东南向西北转移趋势,1960 2012年各分区四季干旱频率呈现增加趋势。[结论]贵州省各分区呈干旱化趋势,且干旱频率和强度呈现不同程度的增加。

Evaluating the Spatiotemporal Evolution of Drought in Guizhou Province Using the SPEI Index

【Objective】Drought could alert hydrological cycle and damage water resources management. Understanding its spatiotemporal evolution is hence essential to regional development. The purpose of this paper is to analyze the spatiotemporal change in drought in Guizhou province.【Method】Monthly precipitation and average temperature measured from 18 meteorological stations in Guizhou province were used to calculate the standardized precipitation-evapotranspiration index from 1960 to 2012. The M-K test, B-G segmentation algorithm, extreme-point symmetric mode decomposition method and the GIS were used to analyze the spatiotemporal evolution of the drought.【Result】The monthly, seasonal and annual SPEI all showed oscillating decrease; there is no significant difference in SPEI between summer and winter. Dry-wet alternation was consistent across the province from the 1960 s to 1990 s, but became inconsistent after the 21 st century. Using the ESMD method, we obtained three IMF components and a R trend component, which showed an increase in drought index. The IMF1-IMF3 analysis showed that the drought had three periods: 2.1 years, 7.6 years and 26.5-year period. The B-G segmentation algorithm gave three distinctive periods: 1960 to 1986, 1987 to 2003 and 2004 to 2012. From 2004 to2012, the northwest endured more droughts in winter, while the southwest saw more drought in spring. There were more droughts in 1987—2003 than in 2004—2012. From 1960 to 2003, the drought appeared to have shifted from southeast to northwest.【Conclusion】Across the province, there has been an increase in droughts in both frequency and severity.