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.