四川省不同行政层级城镇的人口迁移

Population Migration at Different Administrative Levels in Sichuan Province

四川省作为中国第四大人口大省，区域内部的自然和经济条件差异很大，人口在不同行政层级间的迁移导致不同层级人口增减不一。以市、县、小城镇三个行政层级为研究单元，研究四川省城区、县城、镇区人口的时空变化，结果发现：①四川省各等级居民点集中分布在成都平原、川东北、川南经济区，从各行政层级上看，城区人口比重较大，但规模等级结构较小且不完善；县城人口主要集中在10～20万和2～5万两个规模等级，空间上呈现东大西小的局势；小城镇镇区人口规模以1万以下为主。②成都平原、川东北和川南经济区城区人口比重大于镇区大于县城，攀西和川西经济区县城人口比重较大。从前期和末期比重的变化来看，成都平原经济区市区活力较大，且小城镇的增长快于县城；川东北和川南经济区小城镇和县城具有较大的人口集聚作用；攀西经济区县城对人口具有极大的吸引力；川西经济区县城人口比重减少，镇区人口比重增加。③从中心城市和小城镇的空间关系来看，平原和丘陵地区小城镇分布呈现倒u形特征，地形越复杂，小城镇分布越趋于均衡；不同地形区小城镇镇区人口增减不断波动，总体呈现在地形条件较好处，增长间隔大，地形起伏越大处，增长间隔越小的规律。

As the fourth largest population province in China, Sichuan province has great differences in natural and economic condition, which influence the growth of population at different administrative levels. This paper analyzes the temporal and spatial variation of population in three administrative levels-town, county and city. The results show that： （1） Settlements are concentrated in the Chengdu Plain, the Northeastern and Southem economic zone. From the perspective of different administrative levels, the proportion of population in cities is large, but the grades of population＇ s hierarchical structure are low and imperfect; the population scale in counties is mainly 100 000-200 000 and 20 000-50 000, demonstrating the population pattern of greater in the east than in the west; the population scale in towns is below 10 000. （2） Population proportion ranks the first in cities, the second in towns, and the third in county in the Chengdu Plain, the Northeastern and Southern economic zones. While the situation is on the contrary in Pan-Xi and Western economic zones, where it＇s the countries that have the largest population proportion. From the comparison of the early and late proportion, cities in the Chengdu Plain economic zone grow fastest, and towns grow faster than counties; towns and counties in the Northeastem and Southern economic zones have large effects on population agglomeration; counties in the Pan-Xi economic zone are attractive; in the Western economic zone the population proportion has been increasing in towns but decreasing in counties. （3） The distribution of towns shows inverted U-shape in plain and hilly areas. The more complex the terrain is, the more balanced the distribution of towns is; The population growth is fluctuating in different types of counties. In general, the growth interval is greater when the hypsography is smaller.