外洪溃堤一、二维耦合模型与内涝模型叠加在防洪保护区内的应用探讨

Discussion on application of superposition of 1-D and 2-D coupling model for dike failure due to outside flood and water-logging model to flood control protection area

针对防洪保护区河道洪水的漫滩、溃堤及其与内涝叠加耦合预测的难题,以模拟溃堤洪水遭遇区域内涝情况下洪水演进过程为目标,采用基于非结构网格的Roe格式离散控制方程,利用Mike-flood提供的标准连接、侧向连接实现一维与二维模型间的耦联,将溃口口门概化为宽顶堰并添加控制策略实现堤防溃决模拟。采用二维水动力模型耦合降雨径流关系计算净雨过程,建立与区域内涝模型叠加联用的一、二维水动力耦合模型。以中运河南片防洪保护区内洪水演进为例进行分析,结果表明:中运河右堤胡家险工溃决后,洪水向下游演进至房亭河与中运河交汇处的运西洼地内,最大淹没水深位于房亭河与中运河交汇处。模型能够较合理的反映区域内涝分布、地形及主要道路和涵洞对洪水演进的影响,可为区域内防洪抢险工作提供可靠依据。

Aiming at the superposition and coupling prediction of the river flooding,dike failure and water-logging in flood control protection area,the simulation of the flood routing process of that the dike failure flood encounters regional water-logging is taken as the objective,the coupling between 1-D and 2-D models is realized with the unstructural mesh-based discrete control equation of Roe format through the standard connection and lateral connection provided by Mikeflood,and then the simulation of dike failure is realized by means of generalizing the failure-breach into a broad crested weir and adding control strategy,moreover,the net rainfall hydrograph is calculated with 2-D hydrodynamic model coupled with rainfall runoff relation for establishing 1-D and 2-D hydrodynamic coupling models which are superposed and jointly used with the regional water-logging model. The result from the analysis made by taking the flood routing in the flood control protection area of the Mid-Grand Canal in Henan Province as a case shows that： after the failure of Hujia Dangerous Section on the right dike of the Mid-Grand Canal,the downward flood routing extends to Yunxi Depression at the confluence of Fangtinghe River and the Mid-grand Canal and the maximum inundated water depth occurs at the confluence of both the rivers. The model can more reasonably reflect the impacts from waterlogging distribution,landform,main roads and culverts within the area on the flood routing,thus can provide a reliable basis for the flood control and risk elimination therein as well.