中国特大城市人口空间分布与次中心识别研究——以杭州、武汉、西安和沈阳为例

Population Distribution and Sub-center Identification in Chinese Megacities:Taking Hangzhou,Wuhan,Xi'an and Shenyang for Examples

多中心城市空间结构研究已经成为城市地理学的前沿热点内容,但是如何识别次级中心至今仍然没有统一的标准.基于第五次和第六次全国人口普查数据,选取我国特大城市中杭州、武汉、西安和沈阳分别作为东部、中部、西部和东北地区特大城市的代表,运用GIS探索性空间数据分析等方法,结合我国特大城市的人口时空演化特征,测度了我国特大城市人口空间结构的多中心分布特征,并提出了次中心识别标准,为探索特大城市人口的空间重组规律提供了新的思路.研究显示:(1)我国特大城市人口在保持较快增长的同时,还具有明显的"地域分异"和"圈层分化"特征;中心城区人口郊区化现象普遍存在,郊区内部人口密度差异逐步拉大.(2)人口密度在遵循圈层递减规律,其空间拓展呈现出"近郊摊大饼+远郊点状突破"和"轴向连绵扩张"两大趋势.(3)特大城市人口空间集聚总体趋势在不断增强,中心城区及相邻的部分近郊区街道共同构成了人口高密度集聚中心,远郊区则出现了集中连片的低密度人口洼地,且两类地区均呈现扩大趋势.(4)特大城市人口次中心逐步增多,特大城市空间结构呈现出多中心化且逐步增强的趋势.研究为多中心城市空间结构的识别以及城市人口空间布局优化提供了新的思路和依据.

Multi-centers structure research has been a hot spot in the forefront of urban spatial structure research.However,there is no unified standard to identify the sub-center of the city.This paper examined the spatial distribution and evolution characters of four Chinese megacities based on census data of 2000,2010 and GIS Analysis technology.Hangzhou,Wuhan,Xi＇an and Shenyang were selected to represent the megacities in Eastern,Central,Western and Northeastern regions,respectively.After the polycentric analysis of spatial structure,a new method to identify the sub-center of the city was presented in this paper.Result shows：（1）significant regional difference is found between four megacities and circle difference in each megacity.All megacities have experienced the process of suburbanization.（2）Population density difference is increasing between different towns in suburb region.Two spatial expansion models are summarized for the megacities.In first model,megacities are mainly expanded in inner suburbs as well as very few broken in outer suburbs.In second model,megacities are sprawling very far along with river,mountain or transport lines.（3）The population spatial agglomeration is very high and increasing.Both spatialagglomeration and spatial diffusion exist in the megacities.（4）Increasing sub-centers means polycentric structure has been formed and is constantly enhanced in megacities.This research provides some new thoughts for sub-center identify and suggestions for the population distribution optimization of the megacities.