ObjectiveCentral 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.
MethodBased 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.
ConclusionThe 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.