Remote Sensing Monitoring Of Urban Expansion And Evolution Of Urban Thermal Landscape In Baotou City

The past 40 years of reform and opening up have been a period in which China's urbanization has created a world miracle and great achievements have been made in urban agglomeration construction.With the rapid economic development,China's urbanization rate has increased from 17.9%in 1978 to 59.58%in 2018.The number of permanent urban residents has increased rapidly from 173 million in 1978 to 831 million in 2018.The process of urban development has begun to enter a new stage of urbanization with Chinese characteristics.While promoting social and economic development and urban population growth,urbanization caused urban environmental problems and ecological damage phenomenon to the construction of human settlements.Ecological sustainable development has been impacted significantly.Among them,the rapid development leads to the change of the thermal properties of the underlying surface of the city,breaks the balance of surface energy balance,and leads to the transformation of the surrounding atmospheric circulation,thus causing the average temperature of the city far higher than the average temperature of the suburbs,and the urban thermal environment pollution.In this paper,Landsat/OLI remote sensing image data and night light data covering a span of 26 years and four periods were used to obtain the main built-up areas of Baotou city by ENVI and GIS spatial analysis technology,extract the boundaries of built-up areas,and conduct corresponding analysis on urban expansion.Use four phase of the Landsat images at the same time,surface temperature inversion,on the basis of the extension of a city,to research the urban thermal research and analyze the space-time evolution of the landscape pattern,and then explores the Baotou city with the expanding of urban area,the surface thermal environment of heat island intensity change,thermal landscape pattern evolution and characteristics of space points to the opposite sex.In general,this study provides some scientific references for the evolution law of urban thermal environment in Baotou and the evolution of urban thermal landscape pattern by urban expansion.The main conclusions are as follows:(1)The boundary of urban built-up areas in Baotou city based on weighted fusion method can reflect the urban expansion intensity of Baotou city from 1992 to 2018.Along with the social economy,traffic,population images,such as Baotou city development pattern characterized by "radiation"outward expansion,gradually built up area live from "one liang city" two chip pattern gradually close to the city center,the Kunduz shimron area,castle peak district,Jiuyuan district,east river area closely together,will fill rich original middle ground.From 1992 to 2018,the area of urban built-up areas increased from 81.551 square kilometers to 203.009 square kilometers,and the dynamic attitude of urban expansion was 3.573%.(2)Based on the BI algorithm,the surface temperature in the research area was inversed to obtain the spatial and temporal evolution rules of the urban thermal environment in Baotou from 1992 to 2018.Overall,Baotou land surface temperature in 26 years as a whole rose 3.59?,and the trend of first increased and then declining,from 2000 to 2010,Baotou around the mountain for a large number of mining industry development,cause the rock surface exposure,radiation,the surface temperature rise rapidly,after the government through to the ecological environment governance and increase urban green space,the overall urban thermal environment better.(3)Calculate the intensity of urban heat island and grade and classify the urban thermal landscape.The results are used to estimate the landscape pattern index,which reflects the influence of urban expansion on urban thermal landscape pattern.In the past 26 years,the intensity of urban heat island in baotou has been increasing,the area of urban built-up area has been expanding,the area proportion of high-temperature area and sub-high-temperature area has been decreasing,the proportion of medium-temperature area and sub-medium-temperature area has been increasing,and the low-temperature area has remained basically unchanged.(4)The thermal landscape pattern index of Baotou city was analyzed from the patch level and landscape level to reflect the impact of urban expansion on the spatial layout of thermal landscape pattern of Baotou city.With the expansion of the urban area,the patch density of the urban high-temperature area decreases on the whole,the heterogeneity of the landscape space decreases,the scale of the high-temperature patch increases,and the region continues to spread,showing an expansion trend similar to that of the urban area expansion mode.