City Flood Simulation And Risk Assessment System Based On Cellular Automata

Due to the rapid development of urbanization,a large number of natural wetlands and rivers have been covered by impermeable artificial surfaces,resulting in ineffective surface runoff.In addition,urban flooding is becoming more and more common due to the increase in heavy rainfall caused by the greenhouse effect and the limited drainage capacity of urban drainage systems due to aging and lack of maintenance,posing a major threat to the sustainable development of cities and the safety of their residents.Therefore,this paper focuses on the study of rainfall and runoff processes that cause urban flooding,and develops effective non-engineering measures such as risk assessment and management strategies to prevent and reduce losses caused by urban flooding,and provide scientific basis and data references for urban disaster management.This article takes Lanzhou City as a case study to analyze the causes of its urban waterlogging.Firstly,based on the principle of selecting risk evaluation indicators,the factors affecting the risk are identified,and a risk evaluation system is constructed.Secondly,the fuzzy comprehensive evaluation method is used to complete the waterlogging risk assessment,and a simulation and risk assessment system for urban waterlogging is designed and implemented.Finally,the study is demonstrated through the application of data from Lanzhou City.The main contents of this article are as follows:(1)When constructing an urban flood mode l,the accuracy and timeliness of the model are the main considerations.By analyzing the mechanism of urban waterlogging,most current flood models have certain shortcomings,such as high data requirements,complex operations,and low computational efficiency.Therefore,this paper proposes an urban flood model based on cellular automata,which extends the characteristics and components of cellular automata from five aspects: cellular space,cellular status,neighborhood space,evolution rules,and boundary conditions,to meet the requirements of flood simulation.The evolution rule is the core module of cellular automata,which is responsible for the process of runoff confluence on the urban surface.A Pythonintegrated flood model is developed in this paper,which inputs data,simulates rainfall processes,calculates runoff confluence,and outputs the maximum flood depth.(2)This article comprehensively analyzes the formation mechanism of urban waterlogging disasters.Under the guidance of the indicator selection principle,eight evaluation indicators were selected from three aspects: the danger of disaster-causing factors,the sensitivity of disaster-prone environments,and the vulnerability of disasterbearing bodies,to construct the risk index system of waterlogging in Lanzhou.In this study,a city flood model was used to simulate the flood process in Lanzhou under five different rainfall recurrence conditions,and the depth and scope of inundation in each region under different rainfall conditions were obtained,which were combined with inundation frequency data obtained from Sentinel-1 remote sensing images as disastercausing factors for calculation.Due to the complexity and uncertainty of urban waterlogging,the fuzzy comprehensive evaluation method was adopted for risk assessment,and the weights obtained from the analytic hierarchy process and entropy method were comprehensively processed based on GIS and RS technologies.Python code was used to construct the steps of fuzzy comprehensive evaluation,and the results of the danger,sensitivity,vulnerability,and comprehensive risk assessment of urban waterlogging under different rainfall scenarios were finally obtained.(3)This study designs the overall architecture of a system based on the Django,Geo Django,and Django-Raster frameworks.To meet the requirements of flood simulation and risk assessment,the Postgre SQL database is selected,and the system’s data storage architecture is built using the spatial database extension function of Post GIS.The data display interface is built using the Cesium 3D map engine and Vue front-end framework to provide users with a more realistic visual effect.