Evaluation Of Natural Environment Suitability For Human Settlement In Chongqing Based On Grid Data

With the rapid development of social economy and the appearance of diverse ecological problems, people pay more and more attention to their own living environment. Ecological environment not only directly affect the people's health and life quality, but also is related to human development and social progress.In this case, to strengthen the research about the natural condition of living environment can provide scientific basis for long-term planning of regional development and coordinante the development between regional population, resources and environment. And to analyze the spatial distribution of natural environment suitability for human settlement scientifically has a practical significance for dividing the functional district correctly and guiding the distribution of population reasonably.Topography, climate, hydrology and vegetation are the basic natural elements which directly affect the human's life and are closely related to the suitability of human living environment.Based on GIS technology, remote sensing technology and the basic data for the study area including meteorological data from 49 weather stations in Chongqing and surrounding provinces from 1971 to 2000,1:25 million Digital Elevation Model(DEM),1:10 million land use data (2007), Normalized Difference Vegetation Index (NDVI) from 2000 to 2008, geological hazard maps, population data and other relevant data, this paper builds the various types of underlying database and function models and calculates Relief Degree of Land Surface(RDLS), Temperature Humidity Index(THI), Wind Effect Index(K), Water Resource Index (WRI) and Land Cover Index(LCI) based on 100m×100m grid-scale. Next, with assessment method of individual indicators combined with a number of indicators, this paper sets up the Human Settlement Environment Index (HEI) model. Finally, it classifies the HEI based on natural breaks method and comprehensive assessments the natural environment suitability for human settlements in Chongqing quantitatively. The results show that:(1) Non-suitable region with the area of 3905.39km2 accounted for 4.84% of the total area of Chongqing, and is mainly located in the area above the altitude of 2000m of the Taba Mountain, Mt. Wu and Wuling Mountain situated in northeast and southeast of study area, where the RDLS is the largest while the climate suitability and LCI is the lowest. In short, it is unsuitable for living.(2) Low-suitable area covers an area of 12918.78km2, namely,16.02% of the total area. It is scattered in the northeast, southeast and south's mountain slopes with difficult terrain and high elevations, where RDLS is larger, the climate suitability and LCI is lower and the precipitation of leeward slope is less.(3) General-suitable district covers an area of 24072.75km2, accouting for 29.86% of the study area. It is mainly distributed in the valley, parallel ridge-valley region, low mountains and hills region which is scattered in the six districts of Chongqing city, Nanchuan district, Liangping county and other transition zones. And the situation of these regions is different:in the parallel ridge-valley region and the mountain area, the climate suitability and precipitation are good, but the RDLS is large; in the hills and some counties areas, the RDLS is low and the climate suitability is good, but the hydrological conditions are not good; in the six districts of Chongqing city, the LCI is the lowest.(4) Moderately-suitable area, covering an area of 23363.83 km2 and accounting for 28.98% of the total area, is mainly located in the northwest edge of Chongqing, including Dazu county and Tongnan county, and is scattered in the transition zone with some terrain change, where RDLS is small, the climate suitability and the LCI are good but hydrological conditions are poor.(5) Highly-suitable area, with an area of 16365.38km2, or 20.3% of the total area, includes the flat regions between parallel ridge-valleies, and the southeast, the northeast and central parts of the transition zone, where the RDLS is the smallest, the climate suitability, the LCI are the best and the WRI is not low. Although the precipitation of some places is not the most, the density of river is high, so the highly suitable area with the best natural environment is the most suitable place to live in Chongqing.In summary, Chongqing is suitable for human settlement relatively, but the spatial distribution of natural environment suitability for human settlement is highly different owing to the complex topography in study area. At the last, this paper validates the results of the study from the grid, district and country scale respectively, by studying the correlation between HEI and population density and a survey of more than 300 students from different districts and countries in Chonqqing. The conclusions imply that HEI can reflect the natural environment suitability of Chongqing very well. In addition, it can provide scientific basis and decision support for long-term planning of "Livable Chongqing", and can also provide a reference to reduce the population pressure in downtown Chongqing, based on quantitative analysis of spatial distribution of natural environment suitability for human settlement.