Analysis of land function classification and transformation in county based on remote sensing image

Land use/cover change caused by urbanization and industrialization had changed the function of land. In order to explore the evolution law of regional land function, taking Huanghua city, Hebei province as the research area, this paper first classified the land function and analyzed the spatial distribution characteristics and law of land function in 2008-2014 using geographic information system (GIS) and remote sensing (RS) data, and then the biological production function and the value of the ecological environment function were calculated using production capacity accounting model and net primary productivity model to reveal the evolution process of land function value. In the course of land function classification, based on the tree classification method, the two-level classification systems were adopted. According to the main function of land and the difference of land use pattern, the research area was divided into 6 functional categories and 21 functional subcategories. In order to show the result of land function classification, fully reflect the relationship between the various land functions within the region and reflect the land function type, combination and distribution law of the study area, the land distribution maps of Huanghua city in 2008 and 2014 were drawn respectively taking the leading principle as the basic principle. Then it output the function information in graphic mode. It could be seen through the comparison, the functional area of the biological production in the land function category increased most. It totally increased by 3648.8 hm². It showed that in recent years Huanghua city used land development and consolidation, brick kiln reclamation, fertilization and irrigation, and salt and alkali elimination method. The other functions had improved. It had the ability to provide people with agricultural products. The land area of land biological production was significantly increased. The land area of the ecological environment function was reduced by 8238.3 hm². In recent years, with the rapid development of regional economy, a large number of ecological and environmental function land changed to other functional land use, especially the tidal flat wetland and water area (a total change area of 6246 hm²), and the land with biological production function (3622.1 hm²). The salt field was transformed to raw material supply function by 2124.96 hm². Most of the rest was converted to the load bearing function. Load bearing capacity of the land area had increased by 2265.6 hm². This paper took the biological production function and ecological environment function as an example. The change of function value was analyzed. Production capacity of agricultural land represented the size of the functional value of biological production. Main idea was that in the first place the crop yield per unit area and the corresponding agricultural land use index were established. Then the agricultural land classification unit use indices were substituted into the corresponding function equation. It could be calculated to achieve their yield per unit area. The classification unit of agricultural land could realize that the value of land biological production function was calculated from the yield per unit area yield multiplied by the corresponding area. Ecological service value represented ecological environment function. The value of ecosystem services was based on the spatial and meteorological data. Combining with the investigation of foreign trade, the net primary productivity and other models could calculate. By comparing the value of the function, it showed that the biological production function of cultivated lands and fields had been generally improved from 2008 to 2014; Except the unchanged "the other lands?? ecological environment function", the function values of other sub-functions decreased to different extents. The results could provide scientific basis for land function evaluation, ecological red line delineation and land use planning.