Analysis Of Urban Land Expansion And Its Driving Forces In Jiajiang County

Jiajiang county,located in leshan city,sichuan province,is one of the most important ceramic industry bases in China.Since the reform and opening up,the economy,population and other factors in jiajiang county have changed constantly,and the land use situation in the county has also changed constantly,among which the obvious change should be the change of urban land brought by urban expansion.This paper takes the expansion of urban land use in Jiajiang county and its driving force as the research object,and studies the land use in the county and the expansion of urban land use.The main research process is divided into the following three aspects:(1)Study on land change.By means of remote sensing and GIS,Landsat TM images of Jiajiang county in 2000,2006,2012 and 2018 were analyzed to analyze the change of land use and calculate the change rate of comprehensive land use quantitatively.(2)Analysis and research on urban built-up areas.The built-up area of Jiajiang county was extracted by Arcgis and NDBI index,and its urban expansion intensity,urban center of gravity transfer and urban fractal index were analyzed.(3)Research on driving force of urban land expansion.A driving force analysis and evaluation model was established.Firstly,driving force factors were collected and sorted out in a large number of literatures.Then,entropy weight method was used to calculate and screen out effective driving force factors.The main conclusions are as follows:(1)According to the land use classification map and land transfer change matrix of Jiajiang county in the four years of 2000,2006,2012 and 2018,the change trend of comprehensive land use in Jiajiang county is in the state of unbalanced and rapid growth.The main land sources of urban construction land are woodland and cultivated land.The change rate of urban land use,forest land and cultivated land all show a trend of decreasing year by year,and the urbanization rate will gradually slow down in the future.(2)After the NDBI index was used to extract the urban built-up area in Jiajiang county,the calculated urban expansion intensity index showed that the urban area showed a trend of continuous expansion,and the urban land expansion intensity was in an enhanced state,and the expansion rate was gradually accelerated.The center of urban gravity shows that the trend of urban expansion is shifting from northeast to southwest,which indicates that the direction of urban land expansion is chaotic and not forward-looking.Urban fractal strength is high,which is likely to cause urban congestion and unequal distribution of urban facilities.(3)Use of entropy method and the grey correlation analysis method of driving force factors of urban sprawl in Jiajiang weight analysis filtering and correlation coefficient of sorting,established by many factors,such as economy,population,infrastructure construction,constitute a driving force of the system,and carries on the deep research,research shows that urban sprawl in Jiajiang main forces driving force for economic development,urban infrastructure construction,etc.(4)According to the obtained multiple indicators and data,the author puts forward some countermeasures and Suggestions for the future development of Jiajiang county,such as defining the central city and its development direction,making industrial intensification and rationalization development,establishing ecological protection space,and making full use of the existing construction land.