Spatial Temporal Evolution Characteristics Analysis Of Taiyuan Built-up Area In Recent 50 Years Based On Landsat Images

Since the beginning of the 21st century,the urbanization of all countries in the world is progressing faster and faster.Urbanization refers to the process of human society changing from a traditional rural society to a modern urban society dominated by non-agricultural industries such as industry and service industry.The most obvious characteristics in the process of urbanization is the expansion of urban construction area,established as an important reference to direct urban area expansion,accurate insight into the trend of the development of the urbanization and scale,can not only on the city development path of mastery,and can provide scientific reference for future urban development in direction and the suggestion,which plays a good auxiliary decision-making function for the future planning and evolution of the city.Remote sensing data has the characteristics of wide monitoring range,strong timeliness and rich historical data sources.Since the beginning of this century,a large number of remote sensing images have been used as data sources for the research of the built-up areas.In view of this,this paper uses remote sensing data to obtain the boundary of built-up areas,selects the image data of Tai Yuan in the past 50 years as the research object,and explores the track and law of urban development in the process of urbanization of Tai Yuan.Based on the data obtained in recent 50 years,the paper extracts the information of green land vegetation,water resources and bare land in the built-up area of Tai Yuan City,and analyzes the characteristics of land use distribution in the built-up area of Tai Yuan City deeply through the development and evolution law of the proportion of green land resources and water resources in different years.The data sources of this study are mainly based on the data of NASA Landsat series,USGS platform data and the data of Local Space Viewer platform of 31 images.After obtaining the remote sensing image data,the original image data are processed by radiometric calibration,atmospheric correction,image fusion and image enhancement.The OIF optimal index method was used to obtain the optimal band combination of the image data of different sensors,and the image data in each study period were obtained through the image data processing steps.The boundary of built-up area was obtained by manual visual interpretation method combined with the auxiliary correction effect of Google historical image data.Indicators such as expansion intensity,expansion speed,compactness,fractal dimension,urban gravity center migration model and expansion elasticity coefficient were introduced to evaluate the evolution characteristics,expansion rules and reasonability of built-up areas in the past 50 years.By referring to the statistical yearbook data,the multiple regression model among the built-up area,human geography,social economy and other 10 indicators are established to discuss the main driving forces of the expansion of built-up area in Tai Yuan.Based on the 15 m and above the resolution of the image,by Arc GIS and ENVI software using maximum likelihood supervised classification of corresponding time node within the internal classification of land use types,the built-up area from 1990 to 2020 internal classify land use type,to obtain the evolution law of internal green land,water and other resources.Suggestions are made for the future development planning of the built-up area.Through this study,the following points are obtained:(1)In the past 50 years from 1973 to 2020,the built-up area of Tai Yuan has expanded by15.12 times,with an average annual increase of 7.85 km~2/a.The compactness of the built-up area in Tai Yuan is generally low.Combined with the geographical location of Tai Yuan,which faces mountains from east to west,it shows that the expansion of the built-up area is obvious in the north-south direction.The center of gravity of the city has migrated more than 3500 m along the southwest direction of about 30°.The expansion of the built-up area of Tai Yuan has experienced the pattern of rapid growth,steady growth and steady growth successively.The expansion mode of the built-up area in Tai Yuan as a whole is not coordinated with the population growth and the urban structure.The urbanization progress is faster than the population growth.The development of the built-up area needs to be further optimized.(2)The main factors that caused the expansion of the built-up areas in Tai Yuan were economic factors,followed by the scale of population expansion and the output value of industrial chain.Among the results of this research,GNP and per capita GDP are the most important driving forces for the expansion of Tai Yuan built-up area.Population expansion is also one of the leading factors,so the future expansion and construction of Taiyuan built-up areas need to consider the local economic conditions.(3)By comparing the statistical data of the built-up areas in the past 40 years,it is found that since 1990,the built-up areas in Tai Yuan mainly occupied by residential areas accounted for more than 80%of the total area,which experienced a pattern of decrease and then increase successively.The proportion of green area inside the built-up area is maintained at about 14%,and the proportion of water resource area is kept at 1%.The proportion of undeveloped land area was the largest in 2013,and decreased sharply in the past 10 years,indicating that the internal building facilities in the built-up areas were gradually full.