Urban Waterlogging Risk Simulation And Influencing Landscape Factors

Due to the advancement of urbanization and the impact of climate change,urban flood events occur frequently,causing great damage to people’s health and property safety.The construction idea of "sponge city" arises at the right moment,giving full play to the retention and absorption function of urban green space can reduce rainwater runoff from the source.However,there are few studies on flood analysis and impact of landscape factors on regional large-scale.Therefore,the study on the driving effect of the current spatial differentiation of green space pattern on waterlogging risk areas can provide suggestions for the improvement of green space spatial pattern and urban development planning in landscape.In this paper,SCS-CN model was used to simulate the surface runoff under different rainfall return periods,and surface submergence analysis was carried out according to the catchment area,so as to obtain the submergence range and submergence depth under different rainfall return periods.Then,the macro and micro patterns of urban green space are analyzed by using landscape spatial pattern analysis and landscape metrics.Based on the above two steps,the driving force of landscape factors was studied by using Geodetector.According to the above methods,the following conclusions can be drawn:(1)With the increase of rainfall return period,the risk level of waterlogging in the study area will increase significantly,and the submergence area will expand significantly.(2)By analyzing the macro pattern of urban green space,it is found that the core area of urban green space is mostly distributed in the outer circle of the city,and there are few core green space in the central area of the city,and the core area and the edge area are relatively high.(3)By analyzing the micromorphology of urban green space,it was found that the fragmentation degree of green space outside the study area was low and the internal connectivity was strong,while the fragmentation degree of green space in the central area was high and the internal connectivity was poor.(4)Geodetector was used to explore the driving forces of macro and micro patterns on urban waterlogging pattern.It was found that the macro green space pattern had a weak explanation for the differentiation of water depth pattern,and the patch density had the greatest influence among the single factors of micro green space pattern.(5)With the increase of rainfall return period,the interaction of micro-green space morphological factors on water depth pattern gradually weakened,and slope factor can significantly enhance the impact of other landscape factors on water depth pattern.According to the research in this paper,the simulation of urban waterlogging risk area is carried out to obtain the risk area,which can provide reference for the deployment of waterlogging control facilities in the risk area,so as to reduce the impact caused by urban waterlogging.When improving urban green space,more attention should be paid to the influence of micro-green space form on water depth pattern.When the rainfall return period is small,the influence of urban waterlogging can be reduced by improving patch density and patch number.When the rainfall return period increases,the influence of topography on runoff collection should be considered.