Spatio-temporal variations of population and population distribution with data at county level in Northwest China in 1990-2010

Based on the population data at county level,the spatio-temporal variations of population size and population concentration decentralization in Northwest China in recent 20 years were studied.The results showed that:(1) The total population continues to increase and the uneven pattern of population distribution will intensify in the next decades;(2) The proportion of population have a significant increase in the region where the population obviously increased or population generally reduced,so as the population obviously inflow areas and the population in general outflow areas;(3)From the results it can be concluded that the county total population growth reduce tend to be frequently and population concentration decentralization get to be strengthen;(4)As the key factors affecting population growth reduce and population concentration decentralization on space,natural environment and economic development will still work in the future;(5) As the urbanization become a overwhelming trend in the country,the most dramatic population changes occurred in the major cities and its surrounding counties and cities in the Northwest region can not be an exception and will become the main carrier to absorb large number of surplus labor and more and more people will settle in the city,but despite this the population out-migration is inevitable according to the environmental capacity.