MIKE 21二维非恒定流模型在北京市延芳淀湿地洪水影响分析中的应用
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摘要
为了研究拟建在北运河滩地上的延芳淀湿地对河道防洪安全的影响,控制湿地建设规模,不增加北运河50年一遇洪水出境洪峰流量,搭建了北运河MIKE 21二维非恒定流模型,模拟湿地建设前后北运河50年一遇洪水演进情况。采用2016年北运河"7.20"洪水监测数据,对模型进行了参数率定;分析了延芳淀湿地建设前后,50年一遇洪水下北运河河道及滩地槽蓄能力、河道水位、流速、流势等水力条件的时空变化。结果表明:滩地内建设延芳淀湿地降低了北运河槽蓄能力,减少了滩地消减洪峰量值,但通过调整湿地地形高程,仍能满足规划要求;湿地建设同时抬升了北运河洪水位,改变了洪水流势,对河道堤防建设有一定影响。研究成果不仅能够为延芳淀湿地的设计建设提供相关水力条件支持,也可以为北运河河道治理及防洪预案修订提供参考。
In order to study the impact from the planned Yanfangdian Wetland to be constructed on the floodplain of the North Grand Canal on the flood control safety of the river channel and then control the construction scale of the wetland without the increase of the peak flood outflow of the flood with the return period of 50 years from the North Grand Canal,a MIKE 21 2-D unsteady flow model for the North Grand Canal is established herein for simulating the flood routings of the flood with the return period of 50 years from the North Grand Canal before and after the construction of the wetland. The parameter rating of the model is made with the monitoring data of the "7. 20 Flood"of the North Grand Canal occurred in 2016,and then the temporal and spatial variations of the hydraulic conditions therein,such as the water storage capacities of both the river channel and the floodplain,the water level of river channel,the flow velocity,the flow regime,etc.,under the condition of the flood with the return period of 50 years before and after the construction of the wetland are analyzed. The result shows that channel water storage capacity of the North Grand Canal is to be reduced along with the decrease of the magnitude of flood peak clipping by the construction of Yangfangdian Wetland within the floodplain,however,the planning requirement can be met through adjusting the elevation of the terrain elevation of the wetland. Meanwhile,the construction of the wetland raises the flood level of the North Grand Canal and changes the flow regime of flood,which has certain impact on the construction of the embankment for the river channel. The study result can not only provide the support of hydraulic condition for both the design and construction of Yanfangdian Wetland,but also can provide references for improving the river channel and revising the flood control pre-scheme for the North Grand Canal.
In order to study the impact from the planned Yanfangdian Wetland to be constructed on the floodplain of the North Grand Canal on the flood control safety of the river channel and then control the construction scale of the wetland without the increase of the peak flood outflow of the flood with the return period of 50 years from the North Grand Canal,a MIKE 21 2-D unsteady flow model for the North Grand Canal is established herein for simulating the flood routings of the flood with the return period of 50 years from the North Grand Canal before and after the construction of the wetland. The parameter rating of the model is made with the monitoring data of the "7. 20 Flood"of the North Grand Canal occurred in 2016,and then the temporal and spatial variations of the hydraulic conditions therein,such as the water storage capacities of both the river channel and the floodplain,the water level of river channel,the flow velocity,the flow regime,etc.,under the condition of the flood with the return period of 50 years before and after the construction of the wetland are analyzed. The result shows that channel water storage capacity of the North Grand Canal is to be reduced along with the decrease of the magnitude of flood peak clipping by the construction of Yangfangdian Wetland within the floodplain,however,the planning requirement can be met through adjusting the elevation of the terrain elevation of the wetland. Meanwhile,the construction of the wetland raises the flood level of the North Grand Canal and changes the flow regime of flood,which has certain impact on the construction of the embankment for the river channel. The study result can not only provide the support of hydraulic condition for both the design and construction of Yanfangdian Wetland,but also can provide references for improving the river channel and revising the flood control pre-scheme for the North Grand Canal.
引文
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