Impact And Simulation Of Impervious Surface Spatial Pattern Changes On Urban Waterlogging

With the rapid urbanization,impervious surface such as construction land gradually replace the permeable surface such as green space.This shift has led to a decrease in soil infiltration rates and underground runoff,an increase in surface runoff,as well as an overloading of drainage system,which increase the possibility of urban waterlogging.Therefore,an accurate understanding of the impact of impervious surface spatial pattern on urban waterlogging is of great significance to assist the government’s decision-making and alleviate waterlogging issues in urban areas.This study takes Lin’an Sports Culture Exhibition Center and its surrounding area as an example.Firstly,construct an urban waterlogging model based on Info Works ICM(Info Works Integrated Catchment Management).Then,we collected 12high-resolution remote sensing images from 2010 to 2022 to rebuild the impervious surface proportional change dataset.Through multi-scenario simulation,we obtained the the results of urban waterlogging process parameters such as surface runoff,number of overflows and total overflow volume at nodes,proportion of overloaded pipelines,maximum waterlogging depth and extent.And the impact of impervious surface proportional change on urban waterlogging was quantitatively analyzed.Meanwhile,based on the impervious surface proportion in 2022,considering the influence of water flow direction,pipe network distribution and landscape pattern,seven impervious surface spatial distribution scenarios(S1-S7)in three groups were designed to analyze the best impervious surface spatial distribution scenarios for each group.Finally,four optimal impervious surface spatial distribution schemes(Y2-Y5)were designed and simulated to analyze the impact of impervious surface spatial distribution change on urban waterlogging.The results are as follows:(1)An urban waterlogging model was constructed using Info Works ICM.Historical rainfall events on July 31st,2022 and September 13th,2022 were used to calibrate and verify the model parameters.The simulation results showed that the waterlogging depth error range of was between-0.3 cm and 0.5 cm,and the relative error range was between 8.82%and 20%,which indicated the model was reliable.(2)The proportion of impervious surface presented an increasing trend from2010 to 2022.Its area increased from 62385 m~2 in 2010 to 338344 m~2 in 2022,with a total increase of 442.35%.The impervious surface showed an expanding trend from southwest to north-central.The simulation results displayed that the surface runoff,the number of overflows and total overflow volume at nodes,the proportion of overloaded pipelines,as well as the maximum waterlogging depth and extent were positively correlated with the impervious surface proportion.(3)The simulation results of designed impervious surface spatial distribution showed that under the same rainfall condition,the S1 scenario(concentrated in the upstream)of the first group,the S5 scenario(concentrated along the road)of the second group and the S6 scenario(evenly distribution)of the third group had the smallest surface runoff,presenting a better urban waterlogging mitigation effect.(4)The simulation results of the optimization scheme showed that,compared with Y1 scheme(land use in 2022),each optimization scheme can reduce the surface runoff and the node overflow,alleviate the overload pipeline and reduce the maximum waterlogging depth and extent.Among them,Y3 scheme(impervious surface distribution along the road)and Y5 scheme(comprehensive distribution)were better than other schemes in alleviating urban waterlogging.Y5 scheme was best in reducing the surface runoff and the overload pipelines,which reduced the surface runoff of 93.48 m~3 at most.Y3 scheme had the best performance in reducing the total overflow volume of nodes,the maximum waterlogging depth and extent.After comprehensive considering mitigation effect of urban waterlogging and the actual spatial distribution as well as rationality of impervious surface,Y5 scheme had the best effect.This study quantitatively analyzed the impact of impervious surface spatial pattern changes on urban waterlogging from the perspectives of impervious surface proportional change and spatial distribution change.It can serve as a basis for optimizing urban spatial patterns and play an important role in enhancing the prevention and control capacity of urban waterlogging and the level of urban planning and design.