松滋江堤防洪保护区洪水风险研究(Ⅱ)——风险分布特征

Flood Risk of Flood Protection Region Enclosed by Songzi Levee in Complex River NetworkⅡ:Risk Distribution Characteristics

长江中下游地处冲积平原,洪水灾害较为频繁,沿江堤防是生命财产和生产设施的第一道屏障。其中荆江河段洪水峰高量大,且两岸支流众多、江湖关系复杂,防洪形势尤为严峻。以上荆江松滋江堤防洪保护区为研究对象,分析了可能产生的堤防溃口;在对复杂的荆江-洞庭湖水系进行概化的基础上,建立一二维耦合数学模型,研究了1000 a一遇洪水条件下松滋江堤发生溃决后长江干流及防洪保护区内的洪水演进过程,并以最大淹没水深、淹没时间、最大流速、受影响人口及洪水损失为风险要素,分析了保护区内的洪水风险分布情况。文章共分为2篇,此为第二篇,旨在阐述保护区内洪水演进过程及风险分布特征。结果表明,涴市横堤发生溃决后造成的洪水损失最为严重,在实际防汛工作中需要重点关注。

Located in alluvial plain,the middle and lower Changjiang River suffers from frequent flood disasters.Embankment is the first barrier to protect life and property along the river.The Jingjiang River reach in the middle Changjiang River is exposed to a more serious flood control situation because of large amount of high flood peak and complex river-lake relation.In this research,the flood risk in the flood protection region enclosed by Songzi Levee of upper Jingjiang River reach is assessed.The flood routing process in mainstream Changjiang River and the studied flood protection region in the presence of levee break during a 1000-year event flood is simulated using a 1-D and 2-D coupled mathematical model with generalized river network of Jingjiang River and Dongting Lake water system.Maximum flood depth,inundation duration,maximum flow velocity,affected population,and flood losses are selected as risk elements to analyze the distribution of flood risk.The article is divided into two parts.Present here is the second part to expound the flood routing process and risk distribution characteristics in the protected zone.In practical flood control,attention should be paid to the Yuanshi levee which would give rise to the most severe loss once breach occurs.