Flood risk analysis for Yaohu Lake dyke based on coupled hydrodynamic model
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摘要: 鄱阳湖赣江尾闾药湖联圩防洪保护区水系繁多,频繁受到洪水侵袭,因此极有必要对该地区开展洪水风险分析。建立了能够模拟溃堤洪水水流演进的一、二维耦合水动力模型,并利用糙率分区、河道地形还原等技术进行优化,提高了模型精度。将该模型应用于药湖联圩防洪保护区,计算区域采用非结构化三角形网格进行剖分,设定溃口发生瞬时溃堤,溃口流量满足水量平衡原理,演进结果合理可靠。对演进计算结果进行洪水风险分析,结果表明:鸡鸣洲、大王庙、司家闸溃口洪水淹没面积分别为10.62,56.67,18.36 km2,淹没分布基本遵从地形高低原则,保护区内的淹没水深基本都大于3 m,区内洪水淹没范围大小和影响人口数量与溃口位置有关。Abstract: The Yaohu Lake dyke flood protection area in Poyang Lake region has various water systems and complicated hydrological condition. The inundant flood hits the entire region during the flood period, so the corresponding flood risk analysis in this region has a great significance. A 1D and 2D coupled hydrodynamic model to simulate the evolution of levee-breach flood is developed in this study, and the model is optimized by roughness partitioning and river topography reduction, which improves the model's precision. The system is applied to Yaohu Lake dyke flood protection area, and the calculation area is divided into unstructured triangular grids. The instantaneous dike break is set up, and the breach flux meets the principle of water balance. The evolution result is reasonable and reliable, based on which the flood risk analysis is carried out. The analysis results show that the areas flooded due to the breaches of Jimingzhou, Dawangmiao and Sijiazha are 10.62, 56.67 and 18.36 km2 respectively. The submerged distribution basically follows the principle of topography, and the submerged water depth in the protected area is basically deeper than 3 m. And the inundated area size and the impacted population are related to the breach's position.
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Key words:
- hydrodynamics /
- 1D and 2D coupled model /
- Yaohu Lake dyke /
- flood risk analysis /
- levee-breach flood
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表 1 网格糙率取值
Table 1. Grid roughness values
土地类型 糙率 备注 村庄 0.070 居民地 树丛 0.065 幼林、竹林、疏林、成林、灌木林 旱田 0.060 旱地、城市绿地、园地、草地、苗圃、
荒草地、高草地、半荒草地、迹地水田 0.050 表 2 溃口水量平衡验证
Table 2. Water balance verification of breaches
溃口编号 溃口名称 进洪量/m3 保护区内水量/m3 相对误差/% 1 鸡鸣洲 4.028×107 4.025×107 0.07 2 大王庙 1.058×108 1.058×108 0 3 司家闸 3.384×107 3.382×107 0.06 表 3 洪水风险数据统计
Table 3. Statistics of flood risk data
溃口编号 淹没面积/km2 淹没耕地面积/hm2 受影响人口总数/(万人) 最大淹没水位/m 最大淹没水深/m 1 10.62 681.55 0.45 27.01 >3 2 56.67 3 953.21 2.45 22.67 >3 3 18.36 775.87 0.74 22.13 >3 -
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