Seasonal Droughts from 1961 to 2016 in the Six Basins Across Yunnan Province

Abstract

【Objective】 Climate change will increase the frequency of extreme weathers such as drought and flooding. The aim of this paper is to analyze the seasonal droughts occurring from 1961 to 2016 in the six main basins across Yunnan province. 【Method】 The analysis was based on monthly precipitation measured from 124 meteorological stations across the province from 1961 to 2016. The basin rainfall was calculated using the corrected Thiessen polygon method, and the CSPI (corrected SPI) method was used to calculate the drought index by dividing droughts into moderate drought, severe drought and special droughts. Seasonal drought intensity, occurring time of the droughts at the meteorological stations in different basins were used to analyze the spatiotemporal variation in the drought across the province. 【Result】 There are 6 spring drought type meteorological stations, 69 winter drought type meteorological stations and 49 strong winter drought type meteorological stations across the province. The drought in all basins occurred mainly in winter and spring. Spatially, Jinsha basin saw the severest droughts in in winter and spring, followed by Honghe and Lancang basins. Temporally, there have been a decrease in winter and spring droughts in all six basins over the 65 years. 【Conclusion】 The corrected Thiessen polygon method and CSPI method are adequate to calculate spatiotemporal variation in droughts at basin scale. There were local seasonal droughts occurring in the middle reaches of Jinsha basin (Kunming and Chuxiong) and the middle reaches of Honghe basin and the lower reaches of Lancang basin (Jinghong and Pu’er).

Keywords

• basin drought
• corrected spi
• modify thiessen polygon
• drought difference
• yunnan province