基于SPEI干旱指数的陕西省干旱时空分布特征分析

陕西省属于生态脆弱区且旱灾频发。基于陕西省1956-2016年18个气象站点的实测气象资料,利用Penman-Monteith模型计算年尺度标准降水蒸散指数(SPEI),并结合滑动平均、MK检验、小波分析和Kring空间插值法等方法探讨了陕西省61年来的干旱时空变化特征。结果表明:从时间变化上看,陕西省SPEI指数呈现在波动中下降趋势,表明全省正在向干旱化发展,但总体变化趋势不显著;全省干旱影响范围自1986年起呈现显著扩大化趋势; SPEI指数在1980年出现突然减小的变异点; SPEI指数周期存在多时间尺度特征,具有5,16和30a的三个主震荡周期;从空间变化上看,全省有不同程度干旱发生,各站点分布差异较大且不均衡,干旱频率由大到小依次为中旱轻旱特旱重旱,重旱发生频率最低,高值中心位于延安站,中旱发生频率最高且分布范围最大,高值中心位于略阳站和汉中站。此研究可为全省防灾防旱,农业生产以及政策制定提供科学依据。

Analysis on the drought temporal-spatial distribution characteristics of Shaanxi Province based on SPEI

Shaanxi Province is an ecologically fragile and drought-prone area. Based on the measured data of 18 meteorological stations from 1956 to 2016, the annual scale standard precipitation evapotranspiration index (SPEI) was calculated using the Penman-Monteith model. The drought temporal-spatial distribution characteristics of Shaanxi Province during the past 61 years was discussed by combining with sliding average, MK method, wavelet analysis and Kriging spatial interpolation method. The results showed that the SPEI of Shaanxi Province is decreasing in fluctuation from the perspective of time process, indicating an inconspicuous trend that Shaanxi Province is gripped by more severe droughts. In addition, the drought extent in Shaanxi Province has shown a significant expansion trend since 1986. The SPEI shows a aberrance point that suddenly decrease in 1980 and the SPEI cycle has three main oscillation periods of five years, 16 years and 30 years. There are different degrees of drought over the spatial variations, and the difference of station distribution is both big and uneven. The frequency of drought from big to small is moderate drought, mild drought, extreme drought and heavy drought. The frequency of heavy drought is the lowest, whose high value center is located at Yan''an Station, whereas the frequency of moderate drought is the highest and it''s distribution range is the largest, whose high value center is located at Lueyang Station and Hanzhong Station. This study provides a scientific basis for drought disaster prevention, agricultural production and policy formulation in whole Shaanxi Province.