基于SPEI的中亚地区1901—2015年干旱时空趋势分析

Analysis on spatiotemporal trend of drought in the Central Asia region during 1901-2015 based on SPEI

【目的】中亚地区是位于欧亚大陆中心、远离海洋的内陆旱地,其旱地生态系统支持很大比例的人口和经济,评估干旱对该区域可持续性发展有重要意义。【方法】本研究基于1901—2015年空间分辨率0.5°×0.5°的标准化降水蒸散指数(SPEI)月数据,应用关联Mann-Kendall检验和Theil-Sen(TS)slope分析了1901—2015年中亚地区1、3、6和12个月的SPEI(SPEI01、SPEI03、SPEI06、SPEI12)的趋势空间分布情况,以评估不同时间尺度的干旱变化。【结果】研究显示(1)SPEI01在39.24%的研究区面积上呈显著下降趋势(P<0.05),且我国新疆天山山脉以南地区下降幅度最大,为-5×10-4a-1;在45.73%的研究区面积上呈显著上升趋势,其中塔吉克斯坦的上升幅度最大,为3×10-4a-1。(2)SPEI03在76.32%的研究区面积上呈显著下降趋势(P<0.05),其中吉尔吉斯斯坦下降幅度最大,为-4×10-4a-1;在15.39%的研究区面积上呈显著上升趋势(P<0.05),其中塔吉克斯坦上升幅度最大,为3×10-4a-1。(3)SPEI06和SPEI12的趋势空间分布基本相同,且哈萨克斯坦的下降幅度最大,分别为-3×10-4和-5×10-4a-1,塔吉克斯坦的上升幅度最大,分别为5×10-4和6×10-4a-1。【结论】中亚地区年和季节降水的时空变化影响水资源的时空分布,造成不同区域不同时间尺度的湿润化和干旱化趋势。对于哈萨克斯坦中部、土库曼斯坦西南部和我国新疆天山以南地区出现的短期和中长期干旱化趋势以及中亚大面积区域出现的季节性干旱化趋势,当地政府有必要采取相应措施应对干旱,以防治植被退化和荒漠化,保证粮食生产及其人口福祉和安全。对于其他区域出现的湿润化趋势,特别是极端降水事件增多,当地政府需进一步完善防洪和水利灌溉设施,以防止洪旱灾害扩大和实现水资源的有效利用。

[Objective]Central Asia region is a landlocked dryland located in the heart of the Eurasian continent and far from oceans,and its dryland ecosystems support a substantial proportion of the human population and economy.Thus,the monitoring and assessment of frequent drought is of great significance for the sustainable development of this region.[Method]Based on gridded monthly standardized precipitation evapotranspiration index(SPEI)with high-resolution(0.5°×0.5°),the spatial patterns of trends in SPEI for 1,3,6 and 12-month time scales(SPEI01,SPEI03,SPEI06,SPEI12)were analyzed by a contextual Mann-Kendall test and Theil-Sen(TS)slope estimator during the period of 1901–2015 to evaluate the drought variation at different temporal scales in the Central Asia region.[Result](1)SPEI01 experienced a significant downward trend in an area(P<0.05)accounting for 39.24%of the study area,and the largest decline exhibited in the south of the Tianshan Mountains in Xinjiang of western China with a value of-5×10-4 yearly;SPEI01 experienced a significant up trend in an area(P<0.05)accounting for 45.73%of the study area,of which the largest increase was remarked in Tajikistan with a value of 3×10-4 yearly.(2)SPEI03 showed a significant downward trend in an area(P<0.05)accounting for 76.32%of the study area,and the largest decline exhibited in Kyrgyzstan with a value of-4×10-4 yearly;SPEI03 presented a significant up trend in an area(P<0.05)accounting for 15.39%of the study area,and the largest rise presented in Tajikistan with a value of 3×10-4 yearly.(3)The spatial distribution trends of SPEI06 and SPEI12 were basically the same,and the largest decline was shown in Kazakhstan with a value of-3×10-4 and-5×10-4 yearly,respectively,while the largest increase was shown in Tajikistan with a value of 5×10-4 and 6×10-4 yearly,respectively.[Conclusion]The temporal and spatial variations of annual and seasonal precipitation in Central Asia affect the spatial and temporal distribution of water resources,resulting in humidification and aridification trends at different temporal scales in varied regions.For the short and medium term drought trends in central Kazakhstan,southwestern Turkmenistan and the south of Tianshan Mountains in Xinjiang,as well as seasonal drought trends in a large area of Central Asia,it is then necessary for the local government to take corresponding measures to deal with drought in order to prevent vegetation degradation and desertification to ensure food production and their population wellbeing and safety.For the trend of wetting in other regions,especially the increase of extreme precipitation events,the local government should further improve the flood control and irrigation facilities to prevent flood and drought disasters from expanding and to realize the effective utilization of water resources.