Author(s): Qiang Ma; Sijia Hao; Wangyang Yu; Lin Sun; Yizhu Lu; Wenlong Song; Changjun Liu

Linked Author(s): Qiang MA, Wangyang Yu, Yizhu Lu, Changjun Liu

Keywords: Extreme event; Flash flood; Disaster investigation; Modelling analysis; Henan province

Abstract: Nowadays, the occurrence of extreme rainfall becomes more frequent and often causes serious economic losses and casualties. In July 2021, the Henan province of China has suffered the heaviest rainfall in history. The maximum hourly rainfall in Zhengzhou city reaches 201.9mm/h which is the newest record in China. The Wangzongdian county is around 40km away from the Zhengzhou city, with 5.3km2 area, 28 villages and 1,394 residents. The county is surrounded by hills and the extreme rainfall led to a serious flash flood disaster that destroyed dozens of houses and made many casualties. With the data collected from field investigation, a numerical model was set up to analysis this flash flood disaster. The results shown that: (1) the upstream mountainous catchment has produced the flash flood with very short response time to the downstream, (2) the extreme rainfall fell on the bare soil at upstream has produced big amount of discharge mixed with heavy sediment that blocked the river channel at one arch bridge which let a small “dam break” occurred, and (3) many culverts has also blocked and then changed the flow pass to make the overflow entered the villages through the road. This disaster is a typical flash flood event with characteristics of (1) sudden extreme rainfall covered almost whole catchment, (2) very short response time, and (3) heavy sediment in the flow to block and modify the river path. The knowledge we learnt from this analysis could be helpful to guide the emergency management in the future.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221317

Year: 2022