Numerical Simulation Of Sea Dikes Breaching Flood By Typhoon Storm Surge

As the important water retaining structure, sea dikes play a significant role in ensuring safety in the coastal area,it is also the important guarantee of social economic sustainable development. However, the sea dikes breach tends to happen during typhoon storm surge events due to problems with ground settlement, seawater corrosion, the flood can greatly increase the casualties, economic loss and environmental damage. With the development of economy, the government at all levels pay more and more attention to the safety of sea dikes. Therefore, to improve the disaster prevention and mitigation capacity, it is necessary to compute the sea dikes breaching flood under the condition of storm surge.A wetting and drying scheme-was introduced to improve the marine numerical model Ecomsed2D barotropy mode, which would be appropriate for tidal current simulation on broad mudflat. Combined with the sea surface boundary conditions provided by the Veno wind field model and Fujita-Takahashi pressure field model, a numerical model of storm surge was applied to a reclamation project in the south of Zhejiang, and simulate the storm tide of3typical typhoons in front of the dike, as well as the probable maximum storm surge along the12designed typhoon path.Most of the existing dam-break models are being focused on the study of inland rivers and reservoirs flood, and the study on sea dikes breaching flood caused by marine dynamics is very little, up to now, the papers about the sea dike breaching flood due to typhoon storm surge in the macro-tidal sea area like Zhejiang. Based on the improved Ecomsed model, a comprehensive model combinded with storm surge and sea dikes breaching flood is built for the first time. The finite volume algorithm is used to solve the governing equation. The numerical flux is computed by the HLL approximate Riemann solver to, and the water surface gradient was evaluated by the weighted average of both upwind and downwind gradients. Taking the numerical simulation results of storm surge as boundary conditions of seadikes breaching flow, the model first simulated the flood of the reclamation with different storm tide.The flooded area and depth varying with time were obtained. The time and spatial variation law of submerged depth as well as flow velocity caused by "0608" typhoon was mainly analysed. In addition, the impact of key parameters of model on the flood was discussed, such as the width of dike-breaked, the roughness. Ultimately, the study aims to provide the base of safety design and risk assessment of reclamation project, so as to reduce the loss of sea dikes breaching accident as well as raise the management standard in the construction period and running period.