Study on the Trend of Population Spatial Distribution in Beijing since the Reform and Opening-up: Based on Analyzing the Data of Four Population Census from 1982 to 2010

Based on data from the third,fourth,fifth and sixth population census in 1982,1990,2000 and 2010 respectively,the research analyses the accumulative and diffused changes of population spatial distribution in Beijing so as to disclose the evolution laws of population spatial distribution in Beijing since the reform and opening-up by using methods of population gravity center and population standard deviation ellipse and tools of Arcgis software. The research conclusion shows below. During nearly 30 years,the basic trend is that Beijing's population spatial distribution pattern with the traits as population growth rate raising and population expansion. The growth rate in urban function development area and urban new development area is the highest. The population gravity center is in the north of urban core area of Beijing and keeps relatively stable with little displacement. The population density in Beijing has obvious ladder decrease from the inside out. The difference of population density between inner suburb and outer suburb widens gradually while that between urban center area and inner suburb reduces gradually. The population concentration tendency is distinct in capital function core area and urban function development area,which both locate in the urban core area and inner suburb. The obvious ladder difference reflects the population spatial distribution structure has the relative stability characteristics in the 30 years. The length of both long and short axes gradually shortens,so is the ratio of the long axis and the short axis. With the population expansion in Beijing,these changes about axes reflect that the population spatial distribution appears even stronger centripetal polarization trend and concentric concentration trend. In conclusion,it shows that Beijing is still in the population increment orientation urbanization process.Moreover,the relatively stable population gravity center and standard deviation ellipse show that Beijing is coming to the advanced process of the increment orientation urbanization while the quality orientation urbanization is becoming the main challenge in future Beijing.