沭西片防洪保护区洪水淹没风险特征

沂沭泗流域沭西片防洪保护区外河洪水有山区性洪水特征,其特点是洪峰水位高、历时短、总洪量小,溃堤洪水过程的精确计算是保护区洪水分析的关键和难点。为了精确模拟溃堤洪水过程及其在保护区演进规律,构建了一二维实时动态耦合水动力学模型。河网一维水动力数学模型采用1993年、2003年和2012年的实测洪水资料进行了率定与验证;防洪保护区和骆马湖二维水动力数学模型采用区域调研和查勘测量等方式对模型进行了校正和优化;河道与保护区采用溃口进行耦合计算,实现河道与保护区水量实时交互过程的模拟,模型可以作为洪水淹没要素的计算平台。以沂河50年一遇洪水马头溃口为例,溃口进洪历时13.2 h,洪峰流量537 m³/s,进洪量833万m³;保护区内洪水演进速度快,淹没区总面积107.7 km²。结果表明,沂河马头上、下游河段发生溃决,洪水将沿着白马河向下游演进,可以结合淹没水深、洪水路径和到达时间对人员和财产转移进行转移和安置。

Risk Characteristics of Flood Inundation in Shuxi Flood Protection Area

The flood of Shuxi Flood Protection Area in Yishusi Basin has the characteristics of mountainous flood,which has the characteristics of high water level,short duration and small flood volume.The accurate calculation of dike break flood process is the key and difficult point of flood analysis in flood protection zones.In order to accurately simulate the flood process and its evolution in the reserve,a one and two-dimensional dynamic coupling hydrodynamic model has been established.The one-dimensional model was calibrated and verified by the measured flood data in 1993,2003 and 2012.The two-dimensional model of flood protection area and Luoma Lake has been corrected and optimized by regional investigation and survey.The real-time interactive process of water flow between river channel and nature reserve has been simulated by coupling calculation,which can be used as the calculation platform of flood submergence factors.Taking Matou breach of Yihe River as an example,the flood duration of the breach is 13.2 h,the peak flow is 537 m³/s,and the flood volume is 8.33×10⁶m³.The velocity of flood in the protected area is fast,the flood inundated area is 107.7 km2.It is proved that the breach flood of Matou will evolve along the Baima River to the downstream.People and property could be transferred and resettled by the submerged water depth,flood path and arrival time.