Temporal And Spatial Correlation Between Impervious Surface And Surface Runoff

With the acceleration of urbanization,the increase of urban impervious surface,the frequent occurrence of urban runoff pollution,waterlogging and other problems,resulting in increasing losses,the relationship between urban impervious surface and surface runoff has become a global concern.Therefore,it is of great significance to study the temporal and spatial correlation between impervious surface and surface runoff for guiding the process of urbanization,guiding regional development planning and improving regional ecological environment.Taking Hangzhou city as an example,this paper proposes a linear spectral decomposition method combining double exponents to obtain impervious surface coverage,vegetation coverage and soil coverage,which improves the accuracy of traditional linear spectral decomposition method.This method was used to extract the impervious surface coverage,vegetation coverage and soil coverage of the main urban area of Hangzhou from 1990 to 2017,and then the landscape pattern index was calculated.Then,the results of linear spectral decomposition combined with double exponents are used as data input of SCS-CN model to simulate surface runoff in Hangzhou from 1990 to 2017.Finally,correlation analysis and regression analysis are used to analyze the landscape pattern index of impervious surface and surface runoff.The temporal and spatial evolution characteristics of impervious surface and simulated surface runoff are studied,and the relationship between impervious surface and simulated surface runoff is obtained.In order to verify the regional adaptability of the results,the main urban area of Beijing was selected as the validation area.The results show that:1)The method and conclusion presented in this paper have good regional adaptability and are not restricted by the north and South regions.The linear spectral decomposition method combined with double exponents can effectively improve the accuracy of extracting impervious surface,vegetation and soil,and provide high-precision data input for SCS-CN model.The method of simulating surface runoff by SCS-CN is indirectly verified by overlapping with waterlogging points.The simulated surface runoff has higher accuracy.2)The aggregation degree of impervious surface in Hangzhou research area is relatively high in recent 30 years,and the growth rate tends to be stable.The proportion of impervious surface area in ShangCheng and XiaCheng areas is the highest,and the impervious surface is the densest.The growth rate and intensity of Jianggan area,Xihu area and Gongshu area are relatively large.The simulated surface runoff in Hangzhou research area has been increasing continuously in recent 30 years,and the runoff of 220-240 mm is from the central urban area.The simulated surface runoff in ShangCheng and XiaCheng areas is the highest,which is consistent with the evolution trend of impervious surface.3)The spatial pattern of impervious surface is highly correlated with simulated surface runoff.The number and fragmentation of patches on impervious surface are negatively correlated with surface runoff.The proportion of patches in landscape,patch density and patch aggregation are positively correlated with simulated surface runoff.Surface runoff can be controlled by reasonably controlling the relevant landscape indicators and optimizing the spatial pattern of impervious surface.On this basis,some suggestions to prevent urban waterlogging are put forward,such as increasing land use types such as green space and garden,reducing large areas of impervious surface patches,and dividing impervious surface into more small patches.