| After the devastating floods in the Yangtze River Basin,people paid more attention to the problem of flood control in wetlands..The source of the flood can be not only rainwater,but also the flood discharge from the upstream dam,the artificial break,the dam break,and the tide to the inland.This requires us to have a full understanding of the flood and to respond to possible floods in advance,so it is particularly important to be able to predict the water situation in advance.With the improvement of numerical simulation technology and the rapid development of computer performance,the use of numerical simulation for flood evolution has become a mainstream trend.The numerical model not only can deduct locally limited measured information into the whole computational domain,but also verify historical floods,simulate real-time floods,and predict future floods.The simulation results can provide data support for relevant departments to make flood prevention and mitigation decisions,which makes numerical simulation have important practical application value.Wetland flow belongs to two-dimensional shallow water flow.After reading the research results of a large number of domestic and foreign scholars,this paper starts from the most basic Navier-Stokes equations and derives a more concise Reynolds equation based on actual engineering needs and numerical calculation conditions.According to the characteristics of shallow water flow,ignoring the change of physical quantity in the vertical direction and averaging the N-S equations along the depth,the two-dimensional shallow water equation is derived.Then the paper elaborate the discrete principle and flux calculation method of the HydroInfo two-dimensional hydrodynamic model for the shallow water equation.Secondly,through the simulation of three classical two-dimensional dam-breaking examples,the calculation results of HydroInfo are in good agreement with the measured data,which is in line with the physical laws.It is verified that the HydroInfo model has good ability to capture shock waves with high resolution.The HydroInfo model is comparable to the MIKE21 FM in accuracy and can meet the accuracy requirements,and the meshing is more reasonable and reliable,and can be applied to practical engineering applications of complex terrain.Finally,after fully collecting the basic data such as hydrology and topography of Nenjiang Bay Wetland Park,a two-dimensional unsteady hydrodynamic model was established based on HydroInfo.After parameter calibration,the model can reflect theactual situation.According to different working conditions and flood magnitude,nine different flood calculation schemes are determined for simulation.According to the influence degree of different schemes on the water level and flow field of Nenjiang Bay wetland,combined with flood control planning and engineering requirements,the conclusion that the new road in Nenjiang Bay should be reduced by 1 metre is given.The research results provide reliable reference for flood control decision-making,and provide theoretical basis and data support for the reasonable planning of Nenjiang Bay Wetland Park.It shows that it is feasible to use HydroInfo software to simulate two-dimensional shallow water with complex terrain. |
