The Effects Of Urban Land Use And Vegetation Cover On The Thermal Environment

With the rapid development of urbanisation,urban spatial expansion and changes in ground cover have had a strong impact on the urban thermal environment.The study of surface thermal environment effects from the perspective of urban land use types and vegetation cover can provide theoretical references for urban planning and management.Based on remote sensing and GIS technology,this thesis extracts and analyses the characteristics and spatial and temporal changes of land use and vegetation cover in the study area in 2003,2009,2015 and 2021,and systematically studies the effects of urban land use and vegetation cover on the thermal environment.The main results and conclusions achieved are as follows:(1)The characteristics of land use and vegetation cover changes in Xuzhou urban area were analysed.The support vector machine method was selected for supervised classification,showing that vegetation covers the largest area in the study area,and the area of construction land is on the increase.By calculating the NDVI index of the study area,it showed the characteristics of poor vegetation cover status of construction land and water bodies,and high vegetation cover and good vegetation growth in areas such as cultivated land and mountains.The linear spectral mixture decomposition model was used to extract the vegetation cover of the study area,showing that the area of low and high vegetation cover areas was much larger than other areas in 2003 and 2009,while medium and medium-high cover areas were dominant in 2015 and 2021.(2)The spatial and temporal patterns of the thermal environment in Xuzhou city and the thermal environmental effects of land use and vegetation cover were revealed.The results show that the thermal environment of Xuzhou urban area is spatially heterogeneous and its distribution is basically consistent with the distribution of land use types,and the trajectory of the thermal field coincides with the expansion direction of the city.The mean values of surface temperature in different vegetation cover classes decreased with the increase of vegetation cover.(3)The effects of land use and vegetation cover on the thermal environment in Xuzhou city were clarified.An ordinary least squares model and a geographically weighted regression model were used to fit land use,vegetation cover and surface temperature as a single factor and a multi-factor model respectively,and finally the correlation between vegetation cover and surface temperature for different land use types was analysed.The results show that the correlation coefficient of the multiple linear regression of land cover proportion and surface temperature mean is lower than that of the geographically weighted regression,indicating that the correlation between land use and surface temperature is strongly heterogeneous in space;the regression analysis proves that vegetation and water bodies have a cooling effect,and construction land and bare land have a warming effect;the negative correlation between vegetation cover and surface temperature is stronger than that of vegetation index,and the fit of the geographically weighted regression The negative correlation between vegetation cover and surface temperature is stronger than that of vegetation index,and the fit of the geographically weighted regression is better than that of the ordinary least squares model;the effect of vegetation in reducing surface temperature is stronger in vegetated areas and bare land areas than in built-up areas.The thesis has 25 figures,28 tables and 144 references.