考虑工程合理使用年限的珠江流域多属性洪水风险评估

Assessment of Multi-attribute Flood Risk in the Pearl River Basin Considering the Reasonable Service Life of the Project

洪水具有洪峰、洪量以及历时等多属性特征。以往洪水风险评估忽略了工程合理使用年限的影响,考虑工程合理使用年限的风险指数可更好地描述工程所承担的洪水风险。基于此,选取了珠江流域典型水文站点1997-2017年的日流量资料,采用超定量法选取洪水,使洪水样本更丰富。采用Copula函数构建洪峰和洪量联合分布函数,计算联合重现期,同时考虑联合重现期和工程合理使用年限构建洪水风险指数。结果表明:相同重现期的洪峰洪量组合下,相较于其他站点,郁江发生高洪峰洪水或是大洪量洪水的风险最大,而柳江发生高洪峰同时洪量也大的洪水的风险最大(除10年一遇外);当考虑大(1)型水利工程(大坝,n=50~100 a)的合理使用寿命时,西江上发生高洪峰洪水或大洪量洪水的风险最大;柳江上发生洪峰和洪量均超过设计值的洪水的风险最大。

Flood is characterized by flood peak, flood volume and duration. The impact of the project’s reasonable service life was ignored in previous flood risk assessment. And the risk index considering reasonable service life of the project can better describe the flood risk undertaken by the projects. Based on this, this paper adopts the daily flow data of typical hydrological stations in the Pearl River Basin from 1997 to 2017, and selects floods by the peaks over threshold method to enrich the flood samples, builds the joint distribution function of flood peak and volume by Copula function, calculates the joint return period, and builds the flood risk index with consideration of the joint return period and the reasonable service life of project. The results show that: ① Under the combination of flood peak and flood volume in the same return period, compared with other stations, the risk of flood with high peak or large volume is the highest in Yujiang River, while risk of flood with high peak and large volume is the highest in Liujiang River(except 10-year return period);② When the reasonable service life of Type I large water conservancy project(dam, n=50~100 years) is considered, the risk of flood with high peak or large volume is the highest in Xijiang River;and ③ The risk of flood with high peak and large volume exceeding the design value is the highest in Liujiang River.