Spatiotemporal Variation of Drought in Yunnan Province Calculated Using the Standardized Precipitation Index.

[Objective] Drought is the most important abiotic stress facing agricultural management and economic development in many regions and countries. The aim of this paper is to identify the spatiotemporal variation of drought in Yunnan Province, using the standardized precipitation index (SPI). [Method] Meteorological data measured over the past 31 years from 36 meteorological stations across the province were used in the analysis. Multi-scale variations of the droughts in both time and space were calculated using SPI, GIS, nonparametric Mann-Kendall trend test and other methods. [Result] ①Both annual and seasonal SPI fluctuated temporally, but we identified a small annual increase in spring SPI, small annual decreases in summer, autumn and winter SPI. The autumn SPI varied mostly, and the winter SPI least. The annual SPI varied from -1.95 to 1.44. ②The annual drought frequency varied from 32.26% to 50.00%, with the severity of most droughts varying from mild to extreme range. Spatially, drought occurred more frequently in Wenshan, Honghe, Kunming, Chuxiong and Dehong than in other regions in the province. ③Seasonally, drought frequency in spring, summer, autumn and winter was 39.86%, 39.83%, 38.43%, and 41.33%, respectively. Although drought frequency in different seasons was close, their severity differed considerably. ④Annually, except for five meteorological stations which found increased drought frequency, drought frequency in other stations remained statistically the same. Seasonally, most stations showed decreased drought frequency in spring, eleven stations showed increased drought frequency in summer, and six and two stations showed increased autumn droughts and winter droughts, respectively. [Conclusion] Annual and seasonal drought frequency is spatially heterogeneous across the province. Droughts in the province are seasonal, with droughts occurring in spring and winter more frequently and severely. [ABSTRACT FROM AUTHOR]