Spatial and Temporal Evolution Characteristics of Drought in Yunnan Province from 1969 to 2018 Based on SPI/SPEI

The objective of this article is to describe the effect of precipitation and temperature on the drought characteristics of Yunnan province in China. The rainfall and temperature data from 10 national meteorological stations in Yunnan province during 1969 to 2018 were used to investigate the spatial and temporal evolution of drought in Yunnan province and the difference of drought index based on Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) at nearly 50a different time scales. The results showed that Yunnan province had a frequent alternation of drought and flood, and the larger the time scale, the gentler the SPI and SPEI changes. The recent 50a drought mainly occurred in 1980–1982, 1988–1990, 2003–2007, and 2010–2015, and there was continuous drought and the duration was prolonged. The changes of SPI and SPEI showed a downward trend in different seasons. The linear slopes of SPI and SPEI in spring, summer, autumn, and winter were − 0.0064, − 0.0088, − 0.0057 and − 0.0.0111, respectively, and the drought trend was the most serious in winter. Continuous spring drought occurred in 2009–2010 and 2012–2014. The SPEI values in 2009–2010 and 2012–2014 were − 0.80, − 0.64, − 0.75, − 1.23, and − 1.17, respectively. The spatial distribution of drought frequency in Yunnan province was greatly different, and its distribution rule was more in the north and east, less in the south and west. The drought frequency in Zhaotong (northeast Yunnan) was the highest at 36.53%, the drought frequency in Deqin and Lijiang (northwest Yunnan) were 33.11% and 33.28%, and the drought frequency in Kunming (central Yunnan) Lincang, Lancang, and Simao (southwest Yunnan) were 29.35%, 30.73%, 32.77%, and 28.35%, respectively. This study provided a scientific basis for revealing the spatial and temporal variation rules, evolution trends, regional drought, and drought impact assessment and risk management of drought in Yunnan province.