Quantitative risk assessment of flash floods based on investigation and evaluation of flash flood disaster in Chongqing

Abstract

Abstract Quantitative risk assessment of flash flood is crucial for the development of disaster prevention and mitigation strategies. Based on investigation and evaluation of flash flood disaster and the natural geographic conditions, a flash flood risk assessment framework was constructed considering hazard, vulnerability and resilience. Chongqing, known as the mountain city, was selected as a case study. Results indicate that the risk value of flash flood in Chongqing is between 0.25 and 0.66. The areas of extremely high-risk zone, high-risk zone, medium-risk zone and low-risk zone in Chongqing are 1,707,200, 2,773,800, 2,570,100 and 1,183,700 square kilometers, respectively, which the percentage of area in high risk and above areas is as high as 54.41%. Extremely high-risk areas are mainly concentrated in Wuxi in the northeast of Chongqing, Youyang in the southeast of Chongqing, and Nanan, Rongchang and Hechuan districts in the main urban metropolitan area, while high-risk areas are mainly located in Chengkou in the northeast of Chongqing, Pengshui and Shizhu in the southeast of Chongqing, and Jiangbei and Tongnan districts in the main urban metropolitan area. It is worth noting that extremely high-risk zones are distributed more than 50% in Dadukou, Hechuan, Nanan, Rongchang, Shapingba, Wuxi and Youyang districts, and high-risk zones are distributed more than 50% in Chengkou, Jiangbei, Nanchuan, Pengshui, Shizhu, Tongnan and Yunyang districts, suggesting that these districts should be given more attention in flash flood disaster defense.