Analysis of rainstorm and flood characteristics in the Chaobai River and Jiyun River Basins of Beijing during the "25·7" regional major flood in the Haihe River Basin

Affected by the northward uplift of the subtropical high and the westerly trough, heavy rainstorm will occur in Beijing from July 23 to 29, 2025. In order to grasp the characteristics of the "25·7" rainstorm flood, based on the measured and survey data, the causes of rainstorm, rainstorm flood characteristics, rainfall runoff characteristics, rainstorm flood recurrence period and other characteristics will be comprehensively analyzed. The results show that the rainfall area is mainly concentrated in the Chaobai River Basin and the Jiyun Basin, and the rainstorm center is located in Langfangyu, Miyun District; The rainstorm period is mainly concentrated in 6 h, and there are 10 stations with the maximum 6 h rainfall approaching or exceeding the 100 year return period; The flood process presented the characteristics of"high peak, large volume, and fast speed".The peak flow of Baihe Zhangjiafen Hydrological Station reached 4 380 m³/s, and the peak flow of Juhe Sangyuan Hydrological Station reached 2 260 m³/s, both breaking historical extremes. The research results can provide data support for future flood warning and flood control scheduling, and provide decision support for flood and drought disaster prevention work.