开封市7.20特大暴雨城市内涝风险评估

Urban waterlogging risk assessment of 7.20 heavy rainfall in Kaifeng City

河南7.20特大暴雨由于降雨强度大、历时长、洪灾多发引起了广泛关注,特大暴雨导致郑州、开封等城市出现严重内涝。针对城市内涝风险评估问题,对开封市12个自动内涝监测站点数据进行筛选和分析,构建了由短期风险、长期风险2个维度9个影响因子组成的半结构多层次多目标指标体系,在输入层采用信息熵权向量,在准则层对短期风险、长期风险2个子系统采用熵值权向量、对等权向量、决策偏好权向量3种赋权方法,构成改进风险模糊评价模型。对12个站点的内涝风险进行5个级别(极高、较高、中等、较低、极低)的评估。结果显示:在短期风险评估中,5号站点为极高风险,10号站点为中等风险;在长期风险评估中,6号站点为较高风险,8号站点为极低风险;在目标层的最终评价中,3种方法均显示5号、2号站点风险极高,7号、8号站点风险较低。经过与开封市内涝实际情况对比,认为评价体系和改进模型具有较强的适用性,针对城市内涝风险能够给出短期风险、长期风险、综合风险精准的评估结果,为城市进行排水管网完善、内涝积水点防治等提供可靠的数据支持,为应对暴雨引发的内涝问题制定应急减灾预案和应对措施提供依据。

On July 20,2021,the heavy rain in Henan Province attracted wide attention due to its heavy rainfall intensity,long duration and frequent floods.The heavy rain caused serious waterlogging in Zhengzhou,Kaifeng and other cities.Aiming at the problem of urban waterlogging risk assessment,the data of 12 automatic monitoring stations were screened,and a semi-structural index system consisting of two dimensions of short-term risk and long-term risk and nine influencing factors was constructed.In the input layer,information entropy weight vector was adopted,and in the criterion layer,three weighting methods were adopted:entropy weight vector,equal weight vector and decision preference weight vector,which constitute the improved risk fuzzy evaluation model.Waterlogging risk was assessed at five levels(very high,high,medium,low,and very low)for 12 sites.The results show that:in the short-term risk assessment,site 5 means very high risk,and site 10 is medium risk.In the long-term risk assessment,site 6 is high risk,and site 8 is very low risk.In the final evaluation of the target layer,the three methods all show that the risk of No.5 and No.2 sites is very high,and the risk of No.7 and No.8 sites is low.Compared with the actual situation of waterlogging in Kaifeng City,the evaluation system and improved model are considered to have strong applicability.Accurate evaluation results of short-term risk,long-term risk and comprehensive risk can be provided for urban waterlogging risk,providing reliable data support for urban drainage pipe network improvement and waterlogging prevention and control.It provides a basis for making emergency disaster reduction plan and countermeasures to deal with waterlogging caused by rainstorm.