Analysis of extreme precipitation values and rainfall pattern changes in Wuhan based on minute data

In order to investigate the key disaster-causing factors affecting the severity of urban waterlogging, namely rainfall intensity and rainfall pattern characteristics, based on minute precipitation observation data from Wuhan meteorological station from 1954 to 2024, methods such as extreme value statistics, frequency analysis, trend analysis, wavelet analysis, and fuzzy identification of rainfall patterns were used to carry out an analysis of the variation characteristics with extreme precipitation and rainfall patterns in Wuhan.The results showed that: (1) The precipitation duration within 360 minutes is the period with the greatest variation in precipitation intensity and amplitude. Among them, the precipitation intensity within 60 minutes shows the most significant change. The annual extreme precipitation values from 30 to 1440 minutes generally show a slightly increasing trend overall, but the trend is not significant. One-third of the years have an annual extreme precipitation value that is more than the normal value, with a strong intensity. Among them, the historical extreme precipitation values within 30 to 180 minutes are 0.9 to 1.2 times higher than the normal value, and those within 360 to 1440 minutes are 1.3 to 2 times higher.(2) The periodic variations of the annual precipitation extremes in Wuhan mainly include three time scales of approximately 5 years, 15 years and 25 years. Among them, the 25-year cycle is relatively significant in different precipitation durations.(3) The generalized extreme value distribution method with the highest accuracy was selected to fit the recurrence rainfall of Wuhan. The results indicate that the measured precipitation extremes with a short duration of 30 to 60 minutes reach or approach the high-risk level of a 100-year event, those between 180 to 720 minutes fall between the 50-year and 100-year event levels, and those at 1440 minutes are close to the 50-year event level.(4) The main rain types during the heavy precipitation process in Wuhan are type I and Type IV, accounting for 50.7% of the total. From the perspective of decades, the 1950s and 1970s were dominated by type I and type IV respectively, while other decades were dominated by type I and type IV. From the perspective of precipitation duration, short-duration heavy precipitation within 60 minutes was mainly type I and Type III, 60 to 180 minutes was mainly type I and typee VI, and over 180 minutes was mainly type VI. From the monthly distribution, the peak period of heavy precipitation was from May to July, dominated by type I and type IV, and in August it was dominated by type I. The research results can provide reference for exploring the quantitative relationship between precipitation and waterlogging degree, as well as flood prevention and disaster reduction.