Abstract:

By choosing terrain，land cover, climate and water conditions as the evaluation factors, we used GIS as the main technology platform with 250 m×250 m grid as the basic unit and moving window, evaluated the natural environment suitability of human settlements in Chongqing based on the human settlements environment index (HEI) model. Through the quantitative analysis on GIS, it revealed the geographical characteristics and space model of human settlements natural environment suitability. By adopting the method of natural breaks (Jenks), the sequence of the sample values were divided into five grades：level 5 area that was highly suitable (0821-0681); level 4 area that was moderately suitable; level 3 area that was low suitable; level 2 area that was critically suitable; level 1 area that was unsuitable. It turned out that: (1) From west to east，and also from north to south, the index of nature suitability for human settlement in Chongqing decreased progressively and the index of nature suitability for human settlement in Chongqing was between 0255 and 0821. The suitability of the metropolitan area and the one hour economic circle were generally higher. The suitability of the northeast and southeast of Chongqing were lower. (2) The influence of the hydrological suitability on the nature suitability was not significant, and there was still a part of population distributing in the unsuitable area. In these partitions of nature suitability for human settlement in Chongqing, level 1 and level 2 areas were more limited by nature factors with bigger area proportion, higher hydrological suitability of these regions, yet lower terrain and climate suitability, lower leeward slope precipitation and lower soilvegetation suitability, so they were unsuitable for people to live. However, there was still 1481% of the population distributing in these areas. Critically suitable area ranked first, accounting for about 3453% of the total area of Chongqing; the low suitable area ranked second, about 2252% of the total; the highly suitable area ranked third, about 2114%；the moderately suitable area accounting for about 17.84% of the total area of Chongqing , and the unsuitable area ranked last, only about 396%. (3)On the other hand, the population of the region was concentrated in regions with higher nature suitability, and about 8519% of the population of Chongqing was concentrated in level 1 of common suitable region and above that level, the corresponding area accounted for 615% of the area in study area. The change of the population density in Chongqing went along with the increase of nature suitability for human settlement. Therefore, the spatial pattern of nature suitability for human settlement was reasonable in this paper, and it could better reflect the nature suitability and restrictive characteristics in different areas, and quantitatively reveal the spatial pattern and geographical difference of geographical environment in Chongqing. The research results in the paper could provide a scientific basis for the correct analysis of the spatial distribution of population in Chongqing, the formulation of effective policies, and sustainable development of society and economy