Characteristics of the temporal and spatial evolution of rainfall under the influence of urbanization: a case study of the Beijing-Tianjin-Hebei region

With rapid urbanization in recent years, the frequency of extreme rainfall events has increased in major cities around the world during the flood season, and the social and economic losses caused by heavy rainfall are becoming increasingly serious. The results show that (1) the overall duration of rainfall exhibits a downward trend, and the overall spatial performance gradually decreases from east to west. (2) The mountainous areas are prone to light and moderate rainfall events; the plains are more prone to rainfall events at levels above moderate rain, especially rainstorms and heavy rain events; the probability of light and moderate rainfall events in the suburbs is close to that of the urban areas, but the probability of rainfall events at levels above heavy rain is less than that of the urban areas; the probability of rainfall events of all levels in the outer suburbs is higher. (3) Increase in rainfall in urban areas compared to the southern suburbs is greater. (4) With increasing urbanization, the built environment in the mountainous areas and plains has continued to grow, and the original underlying surface conditions have changed.