Observed trends of different rainfall intensities and the associated spatiotemporal variations during 1958-2016 in Guangxi, China

In a changing climate, drought and flood hazards become more frequent, posing high risks to human life and property. The Guangxi Zhuang Autonomous Region is selected as the study area. The flood and drought records, and the daily precipitation data at 23 stations from 1958 to 2016 are adopted. The temporal and spatial trends of precipitation intensities, precipitation days and the corresponding proportions relative to the total amounts are examined using the Mann-Kendall trend test. The influence of the rainfall intensity on floods and droughts in Guangxi is also investigated. During the past 59 years in Guangxi, there is a significant decrease in light rain, and an increase in rainstorm in general. The larger the rainfall intensity is, the more stations show increasing trends of the corresponding rain events on different time scales (the monthly, seasonal or annual scale). Significant decreasing trends of the number of days with light precipitation are found over entire Guangxi, while increasing trends of the number of days with rainstorm events are widely distributed in most parts of Guangxi. There is a decrease in the number of stations indicating increases in proportion of light precipitation days, while an increase in the number of stations showing increases in proportion of rainstorm days. A significant increase in flood hazards is detected since the 1990s. The precipitation in Guangxi tends to be intensified in the future. The frequency and intensity of drought and flood events are very likely to increase, posing challenges to future agricultural production, water resources planning and management.