基于力学过程的蓄滞洪区洪水风险评估模型及应用

为定量评估分蓄洪工程启用过程中蓄滞洪区的洪水风险等级，创建了基于力学过程的蓄滞洪区洪水风险评估模型。该模型采用二维水动力学模块计算蓄滞洪区的洪水演进过程，利用洪水中人体跌倒失稳公式及洪水中房屋、农作物损失的计算关系式，评估各类受淹对象的洪水风险等级。然后将二维水动力学模块计算的洪水要素与两个物理模型试验值进行对比，表明二维水动力学模块的计算精度良好。最后计算了荆江分洪工程启用时分洪区内洪水的演进过程，并评估洪灾中群众的危险等级和财产损失。计算结果表明:洪水演进至140 h时，蓄滞洪区群众、房屋、水稻和棉花的平均损失率分别为85%、59%、63%和72%。模型中提出的采用基于受淹对象失稳机制的洪水风险分析方法，比以往经验水深法划分风险等级的适用性更好，不仅能为洪水风险管理及蓄滞洪区启用标准制定提供参考，也能推广应用于溃坝或堰塞湖溃决等极端洪水风险评估。

A mechanics-based model of flood risk assessment and its application in a flood diversion zone

In order to calculate the flood risk in flood diversion zones under the condition of the operation of a diversion project, a mechanics-based based model of flood risk in flood diversion zones is proposed. The 2-D hydrodynamic module is used to simulate the processes of flood inundation in a flood diversion zone. A mechanics-based formula for the incipient velocity of a human body for toppling instability, the empirical formulas for flood loss of buildings and crops are adopted to evaluate the flood risks to flooded objects. Then the 2-D hydrodynamic module was verified against the two physical experimental data of flood flows, with a favourable agreement being obtained between the predicted and measured data. Finally, the proposed model was used to predict the flood inundation process and assesse the flood risks to people and property during the operation of the Jingjiang flood diversion zone. The results show the average loss rates of human body, building, rice and cotton would be 80%, 59%, 63% and 72% at 140 h. A mechanics-based method is adopted in the proposed model for flood risk analysis, which is better than empirical methods based on water depths in evaluating flood risk. It would be helpful for flood risk management and providing a reference to the operation standards in flood diversion zones, and could be applied to risk analysis of extreme floods such as flows of dam-break and landslide dam break.