Effect On The Spatial Distribution Of Impervious Land-use In The Process Of Urban Surface Runoff

In recent years,the rapid development of social economy has promoted the progress of urbanization,and the proportion of impervious area in the total area of the city has gradually increased,resulting in increased surface runoff,increased peak flow,and earlier peak emergence time.Changes in the production and confluence mechanism have triggered various water disaster phenomena.As people pay more and more attention to urban water disasters,it has become an important task for urban water disaster management to accurately and effectively grasp the impact of impervious spatial distribution on changes in urban runoff production.Based on the indoor artificial rainfall runoff experiment,six different landscape pattern indexes are used to characterize the distribution of impervious surface,and the experimental monitoring data and statistical results are analyzed to analyze the impact of spatial distribution of impervious surface on the process of urban runoff generation under a fixed rainfall intensity.mechanism.On this basis,taking a certain area of Handan City as the research area,a regional SWMM model was constructed,and the flow generation and convergence process of the spatial distribution pattern of impervious surface in the experimental plan under various typical rainfall scenarios was simulated and analyzed.The following results were mainly obtained.(1)The existing experimental data analysis shows that only the separation index,the spread index and the runoff coefficient have a strong correlation,and the runoff coefficient decreases with the increase of the spread index and the separation index.When the spread index is 80%～85%,the corresponding runoff coefficients are mostly concentrated here;when the separation index is 3%～6%,the corresponding runoff coefficients are evenly distributed here;the rest of the landscape pattern index and runoff coefficient,The relationship between peak present time and peak flow is weak.(2)The results of the model simulation show that the decentralized impervious surface spatial distribution model is more suitable for the prevention and control of waterlogging under short-duration and low-intensity rainfall scenarios.Specifically,when the return period is 0.5a and 1a,the decentralized impervious surface spatial distribution model has a better control effect on runoff than the centralized impervious surface spatial distribution model;the return period is 2a At the time of 5a,the spatial distribution of the two types of impervious surfaces had relatively small differences in the regulation and control of surface runoff.By exploring the influence of the spatial distribution of impervious surface on urban surface runoff generation and convergence,scientific planning is provided for improving the urban runoff generation and convergence conditions,so as to achieve the purpose of reducing flood peak flow,delaying peak occurrence time,and improving urban waterlogging prevention and control capabilities.Provide reference basis for planning and stormwater management.