Flood Risk Analysis And Assessment Based On Hydrodynamic Model

Flooding is a devastating natural disaster,and the harm to human beings and the ecological environment cannot be underestimated.In order to ensure the safety of people’s lives,promote economic development,maintain social stability and protect the ecological environment,flood prevention and disaster reduction work is particularly important.In flood prevention and disaster reduction,engineering measures and non-engineering measures are combined with each other and complement each other to better serve the purpose of flood control.In the nonengineering measures,the hydrodynamic model can be established for numerical simulation,combined with relevant methods and evaluation systems,the preparation of flood-related charts,the understanding of flood development trends,and the intuitive reflection of flood risk distribution,which provides strong technical support for flood prevention and mitigation,and arranges and prepares for future flood prediction and prevention,so as to better reduce the losses caused by floods.In this paper,the hydrodynamic model is established for numerical simulation,flood risk elements are obtained,and the flood inundation map is realized by combining the flood characteristic method.According to the flood risk elements,the comprehensive risk element assessment system is selected to realize the mapping of the flood risk map,and finally the flood risk analysis and assessment of the relevant area are carried out by combining the flood inundation map and the flood risk map.The main findings of this paper are as follows:(1)A one-and two-dimensional coupled hydrodynamic model was constructed.Through the analysis of the research progress and software of hydrodynamic model,the model construction method and model software suitable for the research in this paper are selected,that is,the one-two-dimensional coupling hydrodynamic model using IFMS software.Considering the comprehensive situation of the study area,the roughness range of one-dimensional river channel was selected with reference to the soil type conditions,which greatly reduced the blindness and workload of selecting the preliminary roughness value based on experience and reference to adjacent rivers.Through historical flooding,the roughness rate of the onedimensional model was determined,and the roughness of the model was verified by combining the roughness of the two-dimensional region,and the error met the specification requirements and the model accuracy was good.(2)According to the flood inundation map and flood analysis results,the total area of flood inundation showed that the total area of flood inundation showed progression with the increase of the recurrence period.Topography and topographic conditions can lead to the development of flood water from low submerged water depth to high submerged water depth,and from flood diffusion to flood accumulation.The completeness of the dike is closely related to the risk of flooding outside the river.(3)In this paper,three flood risk elements are selected for flood risk assessment,the comprehensive risk degree is introduced,and the flood risk assessment system is constructed,and the flood risk map corresponding to the recurrence period is obtained by calculating the comprehensive risk degree of a single recurrence period,and the flood risk map of the full recurrence period is compiled by assigning the value to the standard grid by the area-weighted average method.(4)The flood risk assessment for the study area is as follows: the very high risk and high risk areas are mainly concentrated in the scope of the river,and the risk level of the river channel is gradually reduced from the inside to the outside.Compared with small rivers,the risk level of large rivers is higher,and the risk level outside the river channel is related to the conditions of the embankment,the more complete the dike,the lower the risk level,and in general,the flood risk in urban areas is lower than that in town-level and rural areas.The proportion of flood area in the medium-risk level is the largest,and the proportion of flood area in the very highrisk level is the smallest.