Study On Spatial Comprehensive Evaluation Methodology At County Scale Based On GIS Grid Modeling

Because our country is restricted by “blocking segmentation” of regional space management and "assimilation" model in development orientation for a long time,the lack of differentiation "top-level design" space development guidance triggered some failure of regional resources and environmental degradation,frequent natural disasters and other issues to some extent,and resulted space,economic,social,institutional,environmental,ecological and other complex issues.Aiming at the above problems,the concept of the main functional area was born,which were gradually promoted from the two levels,namely,the state and the provincial level.The objective of study on main function area is to reasonably plan the future economy,population,land use and spatial distribution pattern of urbanization,making the allocation of resources in the area rational and promoting coordinated and effective development of the society.With the transformation of the social principal contradiction in our country,the national spatial planning has entered a new era,and to build spatial planning system with Chinese characteristics have been our country's important mission.Taking main functional area of the country and the province as the foundation,promote the quaternity,namely,spatial evaluation,spatial overlay(that is,the "rules"),space layout and space policy advancing in the city and county territory,among which the land suitability evaluation of space development conditions on the one hand is the traditional advantages of geography field,on the other hand,it also need to be deepen in the aspects of goal-directed,index system,unit analysis,and technical route,etc.,in order to adapt to the practical demand of spatial functional identification county scale.For this,this article takes the Qijiang district in Chongqing municipality as an example,based on "regulations of technology of main functional area at the provincial level",and the present situation of land use data,meteorological data,disaster data,the environment data,social economic data and other basic data needed for spatial planning,by building county territory development suitability evaluation technology system based on GIS grid modeling,it completed district land development suitability evaluation of the Qijiang district,and through comparing different functional area model,it realized the inter-district grid recognition in land and space function in Qijiang district.The main conclusions are as follows:(1)The high-level design stemmed from the index system of "regulations of technology of main functional area at the provincial level” has a clear geographical meaning,concise and efficient approach to integration,so some indexes and algorithm can be used,but another part should be re-modeled aimed at grid unit.In use of the ecological vulnerability evaluation of space,space ecological importance evaluation,these two indexes and social economic development index,the resources environment supporting capacity index,ecological system development limited index and four comprehensive indexes in comprehensive index of land development condition.The index which have been reconstructed including 7 item parameters,namely,land resources development suitability evaluation,evaluation of river basin water resource availability and environmental pollutant emissions intensity,natural disaster risk,the density of population spatial density,GDP and traffic location advantage degree.Finally,it realizes the adaptive grid identification of Qijiang area.(2)Considering the problems of spatial scale in medium county,in order to accurately reveal the suitable pattern of spatial development in county territory,this study uses the evaluation grid unit with highest precision of 25 m * 25 m.The spatial development function index of Qijiang district is between-4.18 to 5.11.According to the spatial distribution of spatial development function index,the areas with higher spatial development function index values are mainly distributed in the central areas of the low terrain,especially concentrated in on both sides along the river,county and town nearby the Qijiang count area,showing the area is suitable for urban development;The area with low spatial development function index are distributed in mountainous areas with more complex topography and vegetation coverage.(3)Using the division model with comprehensive index of land development conditions,national spatial development condition model and fuzzy ISODATA clustering division model,conducted the grid identification of suitable pattern,among which,the proportion of urban space,agricultural space and ecological space is 20.08:37.63:42.29.The ratio of urban space,agricultural space and ecological space is 11.27:45.31:43.42.According to the fuzzy ISODATA clustering division model,the proportion of urban space,agricultural space and ecological space is 16.53:34.20:49.27.By comparing three kinds of regionalization scheme,the "three areas” and the number of features and characteristics of spatial pattern eventually determine the fuzzy ISODATA clustering division model for the optimal model,so as to complete inter-district grid recognition in land and space function in Qijiang district.