丘陵-平原复合小流域多致灾因子洪涝减灾分析

Analysis of Flood Disaster Reduction with Multiple Causing Factors in Hilly-Plain Composite Small Watersheds

我国东南沿海地区常因复杂的洪涝致灾因子和复合的地形特征,导致流域行洪不畅而引发洪涝灾害,建立适合此流域特征的洪涝模拟模型,并通过洪涝减灾分析制定有效的防洪减灾手段十分必要。利用流域数字高程数据、河网数据、土地利用数据等资料,建立模拟沿海丘陵-平原复合流域洪涝过程的水文-水动力耦合模型,探讨基于工程调度的降低洪涝风险的方法。选择浙江省沿海城市—临海市的大田港流域作为研究区域,充分考虑研究区丘陵汇流、水库下泄、潮位涨落、河道初始水位、闸门泄洪等流域特征要素,设计模型边界条件,模拟不同设计洪水以及工程调度影响下研究区的洪水演进过程和洪水淹没情况。结果表明,所建立的模型能够较好地模拟丘陵-平原复合小流域的河道洪水演进过程。对于极易造成洪水淹没的重点防洪区域,通过调节内河初始水位和控制流域内的防洪挡潮闸门有效的缓解了大田港下游主城区和灵湖景区的洪水淹没情况。大田港流域东北侧区域与山丘接壤,下游工程调度对该区域洪水淹没的缓解效果延时。情景模拟结果为研究区洪涝灾害的预演、预报、预警以及预案提供了数据支撑,为城市防洪工程和平原排涝工程的进一步推进提供依据,为沿海丘陵-平原复合型小流域多致灾因子导致的洪涝灾害提供了解决思路。

In the southeastern coastal areas of China,complex flood disaster factors and compounded terrain features often lead to poor flood discharge in watersheds,resulting in flood disasters.Therefore,it is essential to establish a flood simulation model suitable for the characteristics of this watershed and formulate effective flood control and disaster reduction measures through flood mitigation analysis.By utilizing watershed digital elevation data,river network data,land use data,etc.,a hydrodynamic-hydraulic coupled model simulating the flood process in a coastal hilly-plain composite watershed is established to explore methods for reducing flood risk based on engineering scheduling.The Datian Port watershed in Linhai City,Zhejiang Province,is selected as the study area,taking into account watershed characteristics such as hilly convergence,reservoir discharge,tidal fluctuations,initial river channel water levels,and floodgate discharge.Model boundary conditions are designed to simulate the flood evolution process and inundation situation in the study area under different design floods and engineering scheduling influences.The results indicate that the established model can effectively simulate the flood evolution process in the composite watershed of hills and plains.For key flood-prone areas,adjusting the initial water level in the river and controlling flood tide gates in the watershed effectively alleviated flood inundation in the downstream main urban area and Ling Lake scenic area of Datian Port.The downstream engineering scheduling delayed the relief effect on flood inundation in the northeast area of the Datian Port watershed,bordering the hills.Scenario simulation results provide data support for the pre-assessment,prediction,early warning,and contingency planning of flood disasters in the study area,laying a foundation for the further advancement of urban flood control and plain drainage projects and offering solutions for flood disasters caused by multiple disaster factors in coastal hilly-plain composite watersheds.