Study On Multi-Information Refined Early Warning System Of Urban Flood

Under the background of global warming and accelerated urbanization,many cities have become high-risk areas of rainstorm and waterlogging,and the problem of urban flood is becoming more and more serious.Urban flood early warning system can effectively reduce economic losses and casualties caused by floods.In this paper,a multi-information refined early warning system for urban flood was established,which integrated the vulnerability of urban disaster bearing body,inundation information and disaster information evaluation,emergency rescue accessibility.The disaster bearing vulnerability evaluation based on refined land use division and the rescue accessibility evaluation based on improved two-step moving search method were proposed.Through fuzzy comprehensive evaluation method,two-dimensional table method and shortest path method,a comprehensive early warning risk map with multi-information was obtained,which including disaster bearing body,inundation information,disaster information and rescue information.The research results can provide some reference for urban flood early warning and emergency response.This paper relies on the key project of National Natural Science Foundation of China "Research on theory and method of urban flood disaster prediction and early warning based on big data"(51739009)and the project of Henan excellent youth fund "Research on generation method of urban flood disaster emergency plan based on big data"(212300410088).The main research contents and results were as follows:(1)Urban flood vulnerability assessment.In this paper,the urban land use types were finely divided by using multi-source data identification and visual interpretation method.The building types were mainly divided into commercial area,residential area,industrial area and public service area.Secondly,according to urban economic,social,regional characteristics and other factors,the average GDP,population density and regional vulnerability indexes were selected to evaluate the disaster vulnerability of urban flood.The refined land use division and disaster vulnerability assessment can provide data support for disaster information evaluation and emergency rescue response.(2)Evaluation of inundation information and disaster information.Firstly,this paper extracted the inundation information such as inundation depth and inundation range of sub-catchments under the design rainfall scenario.Through superimposed it with the building types,the inundation information of different building types can be obtained.Secondly,the direct economic losses of various buildings were calculated according to the water depth-loss rate-loss value function of cities without disaster data.The research shows that under the scenario of once-in-a-century rainfall,the economic loss of commercial area caused by flood was the largest,accounting for 48.4%of the total loss.Through the analysis,it is found that under the same rainfall scenario,there were differences in early warning levels in regions with different economic levels.For example,under the same inundation depth,compared with industrial areas,commercial areas with high economic value need a higher early warning level.(3)Rescue accessibility evaluation.This paper evaluated the accessibility of emergency rescue response based on the improved two-step mobile search method.The study found that under normal circumstances,the service range of rescue stations within 15 minutes was as high as 96.36%,while under the once-in-a-century rainfall scenario,the road was seriously damaged,and the service range within 15 minutes was reduced to 53.56%.It can be seen that road interruption will greatly affect the emergency rescue response,resulting in a significant reduction in rescue accessibility.(4)Comprehensive early warning and platform development.In this paper,the fuzzy comprehensive evaluation method was used to calculate the comprehensive risk of study area by combining the population density,average GDP,regional vulnerability,inundation risk and loss risk.Based on the two-dimensional table method and the shortest path analysis,a comprehensive early warning risk map with multi-information refinement of disaster bearing body,inundation information,disaster information and rescue information was obtained.In addition,a multi-information refined early warning platform for urban flood was developed by using ArcGIS Engine.The research shows that the comprehensive risk in the west and south of study area was high,but under the rainstorm scenario,the rescue accessibility was significantly reduced due to serious road damage,resulting in the decline of emergency rescue capacity.Therefore,highrisk areas should be prepared for flood control in advance,and try to carry out rescue response in time when the rainstorm does not reach the peak value.