外秦淮河堤防水文失事风险分析

Risk analysis of hydrological failures of levees in external Qinhuai River

结合南京市外秦淮河堤防整治工程,放弃传统的堤防潮位频率曲线线型,采用频率统计分析的方法确定了外秦淮河堤防潮位频率曲线的线型为反高斯分布;根据该堤防现行洪水设计标准推求了反高斯分布参数λ和μ.基于推求的洪水位频率曲线,将堤防水文失事风险分为洪水漫溢风险和洪水漫顶风险.考虑洪水漫顶事件对堤防水文失事风险的贡献权重,分别建立了堤防洪水漫溢和洪水漫顶失事概率计算模型,求出外秦淮河堤防水文失事风险率为0.374%,能满足工程防洪要求.

With regard to the external Qinhuai River regulation project in Nanjing City, the inverse Gaussian distribution curve was determined as the flood level frequency curve of the river course by use of the frequency statistics technique, and the parameters λ and μ of the inverse Gaussian distribution were derived according to the current flood design standard. Based on the flood level frequency curve, hydrological failure risk was divided into flood overflowing risk and flood overtopping risk. Considering the contribution weight of flood overtopping risk to combined risk, numerical models for calculating the probability of flood overflowing and flood overtopping were established respectively. Finally, the risk factor of hydrological failure for levees of the external Qinhuai River was calculated as 0.374 %, which could satisfy the requirement of flood control projects.