Research On Performance Change And Ecological Effect Of Impervious Land In Nanchang City

One of the main manifestations of urbanization is the derivation of impervious surfaces.A large number of natural surfaces are converted into artificial surfaces.Hard pavement and other building materials make water permeability poor and surface runoff changed during rainfall,which will produce and aggravate various ecological effects such as heat island effect,urban waterlogging,biodiversity degradation,and enhanced land use carbon emission capacity.Therefore,it is necessary to carry out research on the changing characteristics of impervious land and its interaction with the urban ecological environment.It has important theoretical support and practical significance for improving urban living environment and promoting high-quality urban development.This article is based on the remote sensing images of Nanchang in 2000,2010and 2020.The spectral index extraction model,the linear spectral mixture decomposition model,and the multi-feature impervious surface estimation model are used.The most accurate impervious surface information is obtained through the accuracy comparison.The evolution characteristics of impervious surface in Nanchang City from 2000 to 2020 were analyzed by using land use transfer matrix,hot spot analysis and spatial autocorrelation.Through Pearson’s correlation analysis,the ecological environment response caused by the expansion of impervious surface was determined.Build a comprehensive ecological effect evaluation index system,and analyze the correlation between impervious surface coverage and comprehensive ecological effect index.In order to propose detailed and effective optimization measures for impervious surface,the common panel data model,spatial quantile model and spatial Durbin model were used to analyze the influencing factors of impervious surface from the perspective of social economy.The PLUS model is used to simulate the spatial distribution of the impervious surface in Nanchang in 2030,and determine the key control areas for the impervious surface in the future.The management priorities and prevention and control suggestions are put forward for Nanchang City and the high-coverage areas and counties of impervious surface,which can provide reference for relevant cities with rapid growth of impervious surface.The results of the study are as follows:（1）Verified by root mean square error and mean absolute error.The impervious surface information obtained by the multi-feature impervious surface estimation model is highly accurate.In 2000,2010,and 2020,the impervious surface areas of Nanchang were 516.13km²,648.63km²,and 1075.12km²,accounting for 6.64%,8.34%,and 13.83%of the total land area,respectively.The growth of impervious surface shows an increasing trend.From 2000 to 2020,the transfer amount of impervious surface was mainly from cultivated land,water area and forest land.From2000 to 2020,the extreme thermal mass in Nanchang was widely distributed in the central urban area,and at the same time,the extreme thermal mass and sub-thermal mass rapidly covered the surrounding districts and counties in a carpet-like manner.The high-value growth of impervious surface in Nanchang is significantly clustered in hotspot areas.In 2000,2010,and 2020,the global Moran’s I of the impervious surface in Nanchang was all greater than 0.The overall impervious surface distribution in Nanchang showed a significant neighborhood distribution,mainly in the pattern of high-high aggregation and low-low aggregation.（2）The impervious surface affects the urban climate,hydrology,biology,green space,CO₂and other ecological and environmental factors.The Pearson correlation analysis shows that the impervious surface has a significant positive correlation with surface temperature,surface runoff,and carbon emissions.There was a significant negative correlation between impervious surface and water network density,habitat quality and vegetation index.From 2000 to 2020,the trend distribution of impervious surface and surface temperature in each district and county was positively correlated with a power function.The impervious surface and surface runoff of each district and county showed an exponential function positive correlation trend.The better the fitting degree of the impervious surface and the water network density in each district and county is a linear function,and the two are negatively correlated.On the premise of good fitting degree,the impervious surface and habitat quality of each district and county have a negative influence on the development of the power function.There is a negative correlation between the impervious surface and the vegetation index in each district and county,and a linear function is more suitable for the relationship between the two.There is a positive correlation between the impervious surface and carbon emissions in each district and county with a well-fitted exponential function.The comprehensive ecological effect index of Nanchang City is continuously decreasing,and the negative impact of impervious surface on the comprehensive ecological effect index first increases and then weakens.（3）Socio-economic indicators such as economic development index,real estate investment,total industrial output value,total population,and passenger traffic all have significant promoting effects on the impervious surface.At the significance level of 10%,the impact of the economic development index in the 0.1-0.5 quantile range of the impervious surface first decreased and then increased.The impact of real estate investment in the 0.6-0.9 quantile range of impervious surfaces first decreased and then increased.The gross industrial output value volatile growth in the range of0.2-0.9 percentile of the impervious surface.The total population volatile growth in the 0.6-0.9 quantile range of the impervious surface.The correlation coefficient of passenger traffic volatile drops in the 0.1-0.9 quantile interval of impervious surface.Considering the spillover effect of the impervious surface,the socioeconomic index,real estate investment,gross industrial output value,and passenger traffic have a positive impact on the impervious surface in the adjacent area,and the total population has an inhibitory effect on the impervious surface in the adjacent area.（4）The PLUS model can better simulate the quantity and spatial distribution of impervious surface in the future.In 2030,the impervious surface of Nanchang City will increase to 1410.48km²,accounting for 18.15%of the total land area,an increase of 335.36km²compared with 2020,an increase of 4.32 percentage points.Under the trend of urban development,the impervious surface of all districts and counties showed a significant growth trend,and the districts and counties with the largest growth were Xinjian District and Jinxian County,which increased by 101.87km²and90.90km².In the future,the fragmentation degree of impervious surface landscape will be weakened,the spatial connectivity of patches will be enhanced,and the degree of interference by human activities will increase.（5）For Nanchang City,it is recommended to adopt the management idea of"regulating the central urban area and preventing and controlling the surrounding districts and counties".Combining the coefficients of various social and economic factors,on the basis of strengthening the adjustment of the level of economic development,real estate investment,and total industrial output value,the quality of life of the people is guaranteed,and the urban framework is expanded.Promote the ability of population agglomeration,and enhance the regional carrying capacity and attractiveness of cities and towns.As far as the Xinjian District and Jinxian County are concerned,in order to prevent the deterioration of the ecological environment in the districts and counties where the impervious surface expansion will be the most serious in the future,the key is to find a balance in the new urbanization.Promote urbanization with people as the core,and improve the system and mechanism for healthy development.Implement the balanced development of the real estate market and reduce real estate construction and excessive investment in the region.