基于MIKE FLOOD耦合模型的洪水淹没风险分析:以北京市某科学城为例

MIKE FLOOD coupling model-based flood inundation risk analysis: a case of a science city in Beijing

为科学制定城市空间发展及相关规划,对城市暴雨洪水进行精细化模拟,以北京市某科学城为例,利用MIKE FLOOD平台,基于基础地理、河道断面、闸坝工程、暴雨洪水、防洪规划及调度等数据构建了河道一维、研究区二维的大尺度、高精度耦合模型,模拟范围包括山区120 km^(2)、平原区267 km^(2)。根据设计洪水和2021年潮白河生态补水实测数据进行了模型参数率定和验证,准确模拟了现状和规划情景下的河道洪水漫溢及洪水淹没情况。结果表明:模拟水位与率定及验证水位差均不大于0.20 m,纳什系数接近于1,均方根误差较小。模型对包含山区和平原区的大区域范围及精细化河道断面和网格尺度模拟结果较好,适用于科学城洪水淹没风险分析。现状条件下,科学城内仅沙河牤牛河基本满足20 a一遇防洪标准,20 a、50 a和100 a一遇洪水条件下科学城淹没面积分别为0.45 km^(2)、0.76 km^(2)和3.06 km^(2),淹没主要集中在沙河中游部分河段以及沙河、雁栖河下游入河口处两岸。规划条件下,科学城内河道基本满足防洪标准,未发生洪水淹没。

In order to make refined simulation of urban rainstorm and flood for scientific formulation of urban spatial development and related planning, a science city in Beijing is taken as the study case herein, and then a large-scale and high-precision coupling model of 1-D river channel and 2-D study area is established with MIKE FLOOD platform based on the relevant data of basic geography, river section, sluice and dam project, rainstorm-flood, flood control planning, flood dispatching, etc.;for which the simulating range includes the mountainous area of 120 km^(2) and the plain area of 267 km^(2). In accordance with the design flood and the measured data of the eco-water supplement for Chaobaihe River in 2021, the model parameters are calibrated and validated, and then the river flood overflow and flood inundation under the current and planning statuses are correctly simulated. The results show that the differences between the simulated water level and the calibrated and validated water levels are all less than 0.20 m, while the Nash coefficient is close to 1 with small root mean square error. The simulated results from the model including the large scale and refined river section and grid scale simulation in mountainous and plain areas are better, thus are adaptable for the flood inundation risk analysis of the science city. Under the current condition, only Shahe Mangniu River basically meets the flood control standard with the flood return period of 20 a within the science city, while the inundated areas in the science city are 0.45 km^(2), 0.76 km^(2) and 3.06 km^(2) respectively under the conditions of the floods with the return periods of 20 a, 50 a and 100 a and the inundations are mainly concentrated at the part of the mid-reaches of Shahe River as well as both the banks of the downstream river entrances of Shahe River and Yanqihe River. Under the planning condition, the rivers inside the science city basically meet the flood control standards without flood inundation.