| The study under the support of GIS extracts urban boundary information in four periods of 1960,1976,1992 and 2008 by the determined rules of urban land, integrating ALOS images and relief maps, And then rebuilds the spatial expansion in Yanji around 50 years. Further, by the means of objective-oriented technology and Supplementary information, urban land data in 1999 and 2008 in Yanji are extracted.By analyzing land area change, calculating the area and rate of expansion of urban land and combining urban non-agricultural population in Yanji in each period, this paper explains the main reason of the changing in urban land. Using coefficient of elasticity of urban land to analyze the reasonable degree of the rate of expansion of urban land, it showes that urban land expansion in Yanji undergoes three stages of stagnation development, high strength development and unreasonable development.Based on the spatial gravity transfer model and fractal model analyze spatial characteristics of urban land expansion around 50 years in Yanji and shows that the position of gravity in Yanji has an obvious change in different period towards different directions; Urban land was mainly based on expansion of the marginal in 1960,1976 and 1992, which began to transfer to the filling of the marginal.By analyzing the type of land use urban, we find its irrational structure, the proportion of industrial land and residential land is slightly less and a serious shortage of municipal land. Expansion of urban construction land occupation of cultivated land is serious, and takes up most of the paddy field for the quality. By analyzing transfers of urban land use area, we know that commercial land use mainly in urban centers reflect in land development, commercial land converted to other land is not obvious, residential land, industrial land, public land for commercial construction sites is a noteworthy; A large proportion of industrial land into residential land, accordingly, one of the main manifestations is residential land converse to industrial land. In 2008 urban land is apart from the conversion of urban land in 1999, but also from urban fringe areas of agricultural land to urban land conversion. According to the radius of urban land use dimension to analyze the type of land use and the land type of gathering and dispersion degree, we know the center to the periphery spatial patterns of the "commercial-residential-Industrial". In analysis of the spatial characteristics of urban land, we explain the spatial patterns change through expansion of discrete points from block-single center-longitudinal growth-like the evolution of multi-axis model.Based on the nature factors of topography, hydrology, climate and the Social-economic factors of population, economy, industryand policy, we analyze driving mechanism of the evolution of urban land space from different angles. |
