Spatial Correlation Analysis Of Urban Landscape Pattern And Thermal Environment

A clear understanding of spatial correlation between urban landscape pattern and thermal environment can provide a theoretical basis for rational layout of urban land and landscape,and help to alleviate the heat island effect of the city.In the process of rapid urbanization,the growth of urban population,human activities such as roads,railway lines,residential areas,and extension of industrial areas have caused landscape fragmentation,and the changes in landscape patterns of these cities have affected the balance of surface temperature and exacerbated heat.The expansion of the environment makes the heat island effect more obvious and reduces human well-being.Therefore,the urban heat island effect has become a widespread concern of all sectors of society.This paper takes the main urban area of Chengdu as the research object,and uses Landsat remote sensing data combined with spatial analysis,landscape analysis and statistical analysis technology to spatially visualize the landscape pattern and thermal environment in the three periods of the study area.Spatial correlation analysis was performed in GeoDa software using global and local spatial correlation analysis.The main research results are as follows:(1)Based on the decision tree classification method and the normalization index,the landscape information of the main urban area of Chengdu is extracted,and the spatial distribution information of the landscape index is obtained by using the moving window algorithm.The spatial distribution map of the landscape fragmentation is obtained by comprehensive mapping in ArcGIS.The closer the plaque is to the marginal area,the lower the value of the landscape percentage index and the connectivity index,while the separation index shows the opposite result,indicating that the plaque in the marginal region is highly fragmented.The degree of connectivity and the maximum plaque index,plaque density,diversity and uniformity show a certain similarity in spatial distribution,while plaque density,diversity,uniformity and connectivity,aggregation,and maximum plaque index space The distribution presents the opposite result.(2)The regular pattern and characteristics of the thermal environment change in Chengdu are analyzed systematically.Using the thermal infrared band information of remote sensing image,the spatial distribution map of surface temperature in the study area is obtained by image-based algorithm,and the spatial and temporal variation characteristics of the heat island in the main city area are obtained by spatial analysis and statistical analysis.The characteristics of the surface temperature change in the study area shows that the maximum temperature has raised and the minimum temperature has decreased.The expansion trend of the heat island is divergent from the center and forms a form of radiation.The expansion trend of the heat island diverges from the center to the outside to form a radiation shape.The trend of the contribution of the central and suburban districts to the entire main urban area is shrinking,and the expansion of the heat island area has shifted from the urban center to the suburbs.The change in the center of gravity of the heat island shows that the development of the main urban area is uneven and there is an offset.(3)The spatial correlation analysis between the landscape pattern and the thermal environment in the main urban area of Chengdu was carried out by using the global Moran's I and local LISA spatial correlation analysis methods.Through analysis,it is found that the percentage of landscape and patch cohesion index of forest land,water area and cultivated land are negatively correlated with temperature,and the decrease will lead to temperature increase.The percentage of the landscape and the patch cohesion index of the impervious and bare ground are positively correlated with the temperature,and the attenuation causes the temperature to decrease.The splitting index,the percentage of landscape and patch cohesion index show opposite results.The fragmentation of the impervious surface and the bare ground landscape is conducive to weakening the heat island effect of the city.The thermal landscape in the urban landscape is mainly impervious and bare land,and the cold landscape mainly includes waters,woodlands and cultivated land covered with vegetation.Based on the analysis,this paper proposes countermeasure proposals for urban heat island management from the aspects of increasing the connectivity of urban cold landscapes,constructing a green roof system,and protecting the existing cooling landscape in the suburbs.The research results provide a reference for the scientific configuration of cold landscapes(forest land and waters)and thermal landscapes(impermeable and bare land),and provide assistance for constructing reasonable urban cooling systems and exploring ways to alleviate urban heat islands.It plays an important role in improving the quality of urban ecological environment and improving urban living environment.