永宁江流域洪水情景模拟分析

Flood Scenario Simulation Analysis of Yongning River Basin

永宁江流域地势复杂,从山区延绵到沿海平原,洪涝致灾因子多样。下游城市区域快速发展导致原有产汇流过程改变,进一步加剧流域防洪排涝压力。以永宁江流域为例,针对河道洪水构建一维水动力模型,以上游长潭水库下泄洪水作为干流上边界,以山区支流洪水作为支流上边界,以偏不利潮型作为下边界,并采用历史台风洪水进行率定和验证;构建一、二维耦合水动力学模型,模拟洪水漫堤后在地表的演进过程。结果表明,构建的水动力模型能较好地模拟洪水水位变化。基于一、二维水动力耦合模型,分别设置5~100 a一遇设计洪水与2019年"利奇马"台风历史洪水2类情景方案进行模拟推演,分析永宁江流域洪水淹没范围并给出相应对策与建议。

The terrain of Yongning River basin is complex.From mountainous area to coastal plain,there are various flood causing factors.The rapid development of urban areas in the lower reaches leads to the change of the original production and concentration process,which further aggravates the pressure of flood control&drainage in the basin.Taking the Yongning River flow area as an example,a 1D hydrodynamic model is constructed for the river flood.The discharge flood of Changtan Reservoir in the upper reaches is used as the upper boundary of the main stream,the flood of mountain tributaries is used as the upper boundary of the tributaries,and the unfavorable tidal pattern is used as the lower boundary.The historical typhoon flood is used for calibration&verification;a 1D&2D coupled hydrodynamic model is constructed to simulate the evolution process of flood overtopping on the surface.The results show that the hydrodynamic model can better simulate the change of flood water level.Based on the 1D&2D hydrodynamic coupling models,two scenarios of 5~100 a return period design flood and 2019 typhoon Lichima historical flood are set for simulation&deduction,the flood inundation range of Yongning River basin is analyzed,and the corresponding countermeasures&suggestions are given.