基于一、二维耦合水动力模型的赣西联圩溃堤洪水风险分析

An Analysis of the Levee-breach Flood for Ganxi Dyke Based on 1D and 2D Coupled Hydrodynamic Model

鄱阳湖赣江下游尾闾赣西联圩防洪保护区水系繁多,水文条件复杂,汛期频繁受到洪水侵袭,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,并应用于赣西联圩防洪保护区。采用糙率分区、网格加密等技术进行优化,提高了模型计算精度,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:在赣江20年一遇鄱阳湖2010年实测水位过程中,保护区内洪水淹没范围大小和影响人口数量与溃口位置有关,淹没分布基本遵从地形高低原则,永建洲、李家垾溃口洪水淹没面积分别为8.46、36.57 km2,淹没水深基本都大于3 m。

Ganxi Dyke flood control reserve in Poyang Lake region has a variety of water systems and complicated hydrological conditions. The flood hits the entire region during the flood period, so the corresponding flood risk analysis in this region is of great significance. This pa- per establishes a 1D and 2D coupled hydrodynamic model to simulate the evolution of levee-breach flood water, then applied to Ganxi dyke flood control protected area. The model is optimized by roughness partitioning and mesh encryption, which improves the model precision. The calculation area is divided into unstructured triangular grids and the instantaneous dike break is set up. The breach flux meets the principle of water balance, the evolution result is reasonable and reliable. Flood risk analysis through calculating results shows that in the case of design flood with recurrence interval of 20 years in Ganjiang River and the measured water level process in Poyang Lake in 2010, the flooded area by the breaches flooding of Yongjianzhou and Lijiahan are 8.46 and 36.57 km2 respectively. The inundated area size and the impact of the popu- lation are related to the breach positions, submerged distribution basically follows the principle of topography and the submerged water depth in the protected area are basically deeper than 3 m.