基于一二维耦合模型的洪水风险区划研究

Flood risk zoning based on 1D-2D coupled model

萍水河湘东段区域受洪水灾害影响较大,历年损失严重。本文使用MIKE FLOOD构建了萍水河湘东段区域洪水演进一二维耦合模型,结合2019年实测水位过程和调查洪痕等资料验证了模型合理性。根据研究区设防情况,确定了20年、50年和100年一遇3种设计洪水计算方案,并分别提取了3种计算方案下的洪水风险特征要素(包括最大淹没水深、最大演进流速和淹没历时等),使用综合风险度法开展了萍水河湘东段区域洪水风险区划研究。结果表明:萍水河湘东段区域洪水风险区划分为极高、高、中和低风险4个等级;其中,中下游无堤防保护区域洪水风险等级为极高或高风险;湘东区县城区域洪水风险等级主要为高风险和中风险,县政府驻地区域属于洪水灾害高风险等级区。本文洪水风险区划成果可为湘东区防洪规划及非工程措施建设提供科学依据。

The region of Xiangdong district of the Pingshui river has been affected by flood disasters,suffering serious losses in previous years.This paper uses MIKE FLOOD to construct a 1D-2D coupled model of the regional flood evolution of the Xiangdong district of the Pingshui river,whose rationality is proved by analyzing the information on the measured water level process and survey flood marks in 2019.According to the study area fortification,this paper determines three calculation options of P=5%,P=2%and P=1%for design flood.The study on the regional flood risk zoning of the Xiangdong district of the Pingshui river is made by using the comprehensive risk method,taking into account the factors of flood risk characteristics such as maximum inundation depth,maximum travel velocity and maximum inundation duration.The results show that the regional flood risk in the Xiangdong district of the Pingshui river is classified into four levels:extremely high,high,medium and low risk.The middle and lower reaches of the river without dike protection have a high risk rating and are classified as the regions with extreme high or high flood risk.The flood risk in the Xiangdong urban regions is mainly in high or medium level,and the area of the county government is in the high flood risk level.The results can provide a scientific basis for flood control planning and construction of non-engineering measures in Xiangdong district.