Land Use/Cover Change Over Nearly Past Twenty Years In Zhongwei City Ningxia Province As Well As Evaluation Of Its Ecological Capacity

Land is the material basis and the most basic natural resources for human survival and development. Land has been utilizing since the birth of mankind. Land use / cover change reflects land use patterns and intensity that human use as production and living materials. With population growth, industrialization process, the expansion of urbanization and technological advancement, people use more land resources than ever before. Population, resources and environmental pressure has triggered increasingly serious conflicts between people and land, which seriously hampered economic and social sustainable development. Analysis and summary of land use / cover change features in Zhongwei City, and judgment on whether Zhongwei's development is in the ecosystem carrying capacity, are of great importance and practical value on land use regulation and decision-making for regional integrated environment and development of Zhongwei City.Supported by remote sensing and GIS technology, this article has made use of three satellite TM image of Zhongwei City in 1992, 2002 and 2009. By image processing and extraction of information, the article has interpreted the current situation of land use / cover of research area, and established land use / cover database. Assisted by the powerful use of GIS spatial analysis function, the article first analyzed land use characteristics of the research area, and then distinguished between the two study periods (1992-2002, 2002-2009), respectively ranging from land use change, the dynamic degree, degree of change to the aspects of spatial distribution. And the driving forces of change from the natural, social and economic aspects of land use are analyzed as well.Utilizing the LUCC database of 1992, 2002, and 2009 combined with socio-economic data and ecological footprint method, the article has calculated the ecological footprint and ecological capacity of Zhongwei City from 1999 to 2009, and made preliminary quantitative evaluation on the extent of their sustainable development.Main research results are as followed:(1) Making use of three satellite TM image of Zhongwei City in 1992, 2002 and 2009, the article has interpreted the current situation of land use / cover of research area, and established land use/cover database of 1992,2002,and 2009 by image processing and extraction of information,(2) Land use/cover area and the dynamic changes area of 1992-2002 and 2002-2009 are obtained after analyzing Land use/cover database of 1992, 2002,and 2009. The results showed that the area of cultivated land increased year by year, which were 36% and 23.5% in this two periods. Mainly for the new reclamation area increased the cultivated land; urban built-up area also increased to 11% and 15.5% respectively; grassland area decreased 1.2% in the period of 1992-2002, and then increased in the period of 2002-2009 with the rate of 0.8%; overall trend of forest area showed an increase, with 15.8% and 6.1%; unused area reduced the most, which were 9.0% and 12.2% of the two periods. It is noteworthy that current urban area are increasing at the cost of occupying the well- cultivated land.(3) Land use dynamics between 1992 and 2002 were the arable land, forest land, and construction land in sequence; however the order changed as arable land, construction land and unused land between 2002 and 2009. It shows that cultivated area kept the fastest growth during the research period.(4) As the development and utilization of land resources increased, the degree of land use in the research area shows a trend of increase after a reduction. The specific degree index of land use of 1992-2009 fell to 291.54 from 294.09, then went up to 292.35.(5) The land use change is due to interaction of the natural, social and economic factors. Geographical environment, climate, topography, soil, national policies, population and socio-economic development are combined factors to land use / cover change.(6) The research results indicate that, nearly 20 years, the per capita ecological footprint of Zhongwei city tends to increase, while per capita ecosystem carrying capacity also has an increasing trend; but the former is larger than the latter in terms of increase rate. It suggests the serious ecological deficit and imbalance between ecosystem supply structure and economic demand structure, which affects the sustainable development of economic construction to a certain extent in this area.