The Spatial Distribution Research Of Population In Lanzhou City Over The Past30Years

The spatial distribution of population is influenced by nature, hi story, society, economic,policy and so on.It is one of the most significant issues in human geography. As the capital of Gansu province,Lanzhou occupies a prominent position in northwest China. For the population distribution variety in Lanzhou has special characteristics,so studying on the population distribution of Lanzhou can help us to know the regulations of population distribution in northwest China.Base on demographic data at a street level, the essay analyzes the spatial evolution of population density in Lanzhou in recent30years, by a comprehensive application of software ArcGIS and GS+Version7. The result shows:①During the evolution of spatial pattern in population density in Lanzhou, with the growth of spatial distance, positive correlation of population density is gradually weakening and negative correlation is gradually strengthening. The spatial autocorrelation range continuously increases. The influence coverage of high density area towards low density area is increasing year by year. The random elements that arouse the spatial difference in population density are increasing continuously, and structuration differentiation that space correlation causes is more and more outstanding. The regional difference in population density distribution is enlarging as a whole. It can be predicted that, in a period from now, the difference remains and in a short term there will no any great changes about it at a short. This illustrates that population distribution in Lanzhou is always in an imbalanced state.②From the changes of population density gravity in different years, it can be seen that, the population distribution is partially on the east. The tendency of space pattern in population distribution bears its regularity, which is high on the east and low on the west as a whole. In Two-center space pattern formed by increase peak in Chengguan District and Xigu District, the population density is gradually reducing from center to the surrounding. The general tendency of population density in different years has not taken place any great changes. The high and low population gravity focuses on Chengguan District and Qilihe District, which shows the gradual and stable eastward tendency and low population density center is moving at a relatively speed. The moving directions of the gravity of high and medium population density and low population density are opposite, which shows that difference of population density in districts is enlarging. Meanwhile, as for high population gravity and medium density center, the area of research units of population gravity in different levels is different. The street area which is high in population density is commonly small, and the street area that is low in population density is generally large.③The differences in population density between the streets in main urban areas existed in30years ago. And the revolution is under combined influences by nature element, history element, policy element and economy element. Among them, nature element is the direct factor that influences population density; history element is the key factor that influences the difference in population density; policy element plays a controlling and leading role in the revolution of space structure in a city; the difference in social and economic development directly influences mechanical growth of population, and makes population gravity transfer. Therefore, economy element is the decisive factor that influences population density distribution.The population extremely uneven distribution brought a series of problems such as environmental pollution, traffic congestion, housing shortage and the rise of unemployment rate. Through these aspects of establishing multicenter urban layout structure, adjusting the industrial spatial arrangement, speeding up the construction of its infrastructure and leading the urban-rural population to mobile rationally and in order to optimize the spatial distribution of population constantly and guarantee the sustainable development of the city.