Analysis of drought and flood characteristics in Hubei Province in recent 62 years

Using the surface meteorological observation data of 76 national meteorological stations in Hubei Province from 1961 to 2022, the drought and flood processes based on the meteorological drought composite index (MCI) and effective precipitation index (EP) are first identified. Then we analyze the spatial-temporal distribution of the frequency of the drought-flood processes, the characteristics of the drought-flood year, the drought-flood transitions over the past 62 years, and the characteristics of drought and flood processes since 2010. The results show that the frequent occurrence area of droughts and floods in Hubei Province is generally characterized by the flaky distribution with floods in the east and droughts in the west, while floods in the south and droughts in the north. The occurrence frequency of droughts and rainstorm floods shows a fluctuating decreasing and increasing trend, respectively. The droughts mainly occur in spring and summer-autumn with a decreasing trend in frequency, but an increasing trend is found in the summer-autumn droughts and extreme droughts. Comparatively, the rainstorms mainly concentrate in summer and show an increasing trend in frequency. The annual variation of drought-flood year is characterized by continuous droughts for 2-4 years, continuous floods for 2-3 years, or alternation of droughts and floods. In some years, droughts and floods coexist in the same year, while abrupt drought-flood transitions are also found. However, there has been no drought-flood coexistence in the same year since 2010. The annual variation of the number of stations with drought-flood transition fluctuates greatly, showing a five-stage increasing characteristic with the maximum value of each stage decreasing. Since 2010, the drought and flood events show characteristics of extreme enhancement, sudden increases, and successive droughts and floods.