Study On Urban Waterlogging Simulation And Early Warning System Based On Multi-source Information Fusion

With the rapid development of urbanization and the change of global climate,the urban waterlogging has become frequently,which has seriously affected the people’s lives and property and public transportation safety.The paper takes the typical area within city proper of Xi’an as the research object.The causes of urban waterlogging were analysised based on the systematic analysis of the historical waterlogging in Xi’an city.The SWMM model of research regional was established.The different scenarios were designed according to the causes of urban waterlogging.The changes of waterlogging were obtained by simulating the node flooding and conduit surcharge based on different scenarios,which could provide the reference for urban waterlogging response.The modern information technology was applied to the urban waterlogging response,the monitoring and early warning system of urban waterlogging integrating monitoring,simulation,warning and information display was designed,which could provide technical and decision-making support for urban flood control and disaster reduction.The main results of this paper are as follows:(1)The causes of waterlogging in Xi’an city were analyzed systematically.The heavy rainfall is the main causing disaster factor of urban waterlogging.In recent years,the heavy rainfall and waterlogging in Xi’an city were occured from April to October.By analyzing the change characteristics and driving mechanism of precipitation from April to October in Xi’an city,it can be known that the precipitation intensity and heavy precipitation of Xi’an city increased.The development of urbanization changed the urban land structure,which has the influence on the regional regional rainfall-runoff process.The ArcGIS was used to analyze the land use change of Xi’an city from 1995 to 2018.The results showed that the the areas of grassland,farmland,woodland and waters were reduced,and the area of construction land was increased,which were lead the water holding,stagnant water and infiltration capacity of surface were reduced,the confluence time was shortened,and the surface runoff was increased.These phenomena in Xi’an city such as the relatively low recurrence period of drainage pipe,the confluence of rainwater and sewage pipes,the reduced density of drainage network and the relatively low management level of drainage facilities,which were reduced the city drainage capacity and easy to cause urban waterlogging phenomenon.(2)The waterlogging simulation of Xi’an city was carried out based on SWMM model.The SWMM model of the research area was constructed.Three scenarios of different rainfall,different urbanization level and different pipe network level were designed according to the causes of urban waterlogging.The urban waterlogging simulations were carried out based on the three scenarios.With the improvement of rainfall recurrence period and urbanization development level,these things such as runoff coefficient,surface runoff,the number of water accumulation nodes and the time of water accumulation increased,which increased the risk of waterlogging occured.In different rainfall scenarios,most of the rainwater pipe network recurrence periods in the study area were less than three years,and the drainage capacity remained to be improved.All pipes with diameter of 0.3m were overloaded,and accounting for the largest proportion of the overloaded pipes.Therefore,the pipes with diameter of 0.3m in the study area were changed to simulate the waterlogging in different pipe network level scenarios.With the increase of pipe diameter,the flow of pipeline system increased,and these things such as the flow over the surface,the number of water accumulation nodes and the time of water accumulation decreased,which reduced the risk of waterlogging occured.(3)The monitoring and early warning system of urban waterlogging was constructed based on multi-source information fusion.The monitoring and early warning system of urban waterlogging integrating monitoring,simulation,warning and information display was designed based on three-dimensional geographic information system platform,adopting J2EE technology architecture,invoking the SWMM.dll,integrating data of spatial geographic,remote sensing,meteorological and hydrological,flood control project and other.The system includes three thematization services of waterlogging basic information service,waterlogging simulation service,and waterlogging monitoring and early warning service.Based on the system,we can realized the inquiry,analysis and display of waterlogging basic information,the simulation of node flooding and conduit surcharge,the dynamic monitoring and grading early warning service of waterlogging,which could provide decision support for quick response and scientific reply to urban waterlogging,improve urban flood control and disaster reduction capacity,and reduce disaster losses.