Analysis on the concentration and decentralization of population in Lanzhou-Xining Cities Region based on the regional density functions

The exploratory spatial data analysis is used to examine the population distribution characteristics of thirty-five countries in Lanzhou-Xining Cities Region, and three high population density centers are found. To make sure which regional density function is more appropriate for Lanzhou-Xining Cities Region, the gravity-based model is used to delineate the radiation scope of these three high population density centers and then the square-root negative exponential density function shows the precedence over the others. Since the monocentric regional density function has limits in multicentric regions, such as Lanzhou-Xining Cities Region, the function based on the square-root negative exponential is used to examine the characteristic and the development trends of concentration and decentralization of population. Compared with the result of monocentric and polycentric functions, it shows the polycentric function is more appropriate in detecting the trend of population movement. And there are two different types of concentration and decentralization of population, where the different levels of population density center display different characteristics, namely, the concentration type, and the dispersion type through weaken center.