An evaluation on changes of rainstorm characteristics in Shanghai Municipality/

Yi Wenlin; Gu Shenghua; Yu Hui; Ding Guochuan

doi:10.3969/j.issn.1000-1123.2024.18.008

Abstract：Affected by acceleration of urbanization and overall impact of global climate change,the total amount and intensity of precipitation in cities of China have increased.High frequency of extreme rainstorm poses serious challenges to the safety of cities for flood control.In order to further extend the flood forecast period and enhance capabilities to cope with flood disasters,the time series of rainstorm characteristic samples was analyzed by using wavelet analysis and Mann Kendall trend test methods,according to the historical data of 32 representative rain gauging stations in Shanghai.The characteristics of rainstorm frequency,intensity,duration and shrouded area in the history shows that they are all periodic.The results indicate that the number of rainstorm is at increase stage from 2023 to 2026,and shall gradually be decreased after 2027.The number of rainstorm shall be at the trough around 2030,with relatively less events.In terms of rainstorm intensity,according to the prediction of fitting trend line,it will have a growth period in the next five years,and the maximum 3h and 6h sliding average will increase by about 20 mm until 2027.In terms of the duration of rainstorm,it is at growth period from 2023 to 2026 and will be at the peak around 2024,with a relatively long rainfall duration.In terms of rainstorm coverage area,it is at increase stage from 2023 to 2024,and will enter into shrinking stage after 2025.Around 2029,it will be at the shrinking trough,and the coverage area is relatively small.