Characteristics of rainstorm with different time scales in Guizhou during 2020 flood season

Based on the hourly rainfall data in the 2020 flood season (April 15 to September 30) in Guizhou province,this paper analyzes the spatial and temporal characteristics of rainfall at different time scales in the flood season. The results show that the total rainfall in the 2020 flood season is abnormally high,which is the highest since 1961 and nearly 30% more than that of normal years. The percentage of rainfall anomaly in September is 208.6%. The total rainfall in 16.7% of the counties in the province exceeded the historical extreme value,and 3.9%,47.1%,96.5% of the stations had the maximum daily rainfall of more than 200 mm,100 mm and 50 mm,respectively. The maximum daily rainfall reached 366.25 mm and the maximum hourly rainfall reached 163.3 mm,both exceeding the historical extreme values in Guizhou. The total rainfall from 20 to 08 o'clock in the 2020 flood season accounts for 69.24 of the total daily rainfall,and the hourly heavy rainfall stations account for 76.3%. In 2020,6h heavy rain occurred at the most stations,with a frequency of 6.34%. 93.47% of the stations in the province had different degrees of sudden rainstorm event,while regional rainstorms are 53.3% more than normal.