Land Use Dynamic Changes And Its Trend Analysis Based On GIS

The Ansai County of Shaanxi Province used to be one of the poorest agricultural counties in Northern Shaanxi region. In the later years, with petroleum exploitation and improvement of agricultural structure, the land use has changed obviously. Also with that, social economy and people living level of the county have entered the increased stage rapidly. To analyze the relationship between social economy development and land use changes, for making agriculture and county developing plan, has an important theoretical value and practical significance. Based on the previous research achievements and local statistical data, the comprehensive land resource database has been established. Then the land use changes and the driving forces have been analyzed. The main achievements are followings.(1) The comprehensive land resource database of Ansai County has been established based on the GIS technology and integrated various space data that are related to the land use. The main data include natural properties of land resources, land use changes, and social-economic development data. These can make a valuable support for local government making decision.(2) According to the statistical data, due to the implementation of the project conversion agriculture to the forest (grass) and the adjustment of countryside industrial structure, the cropping land area of Ansai County occupied 28.37% of the total land area in 2005. It is closed to the property (29.95%) of the suitable land (including critical land) for cropping based on the land natural characteristics ( including landform, slope, soil nutrient , soil erosion , soil moisture and others),(3)The main characteristics of land use changes of Ansai County are: The cropping land and grass land reduced 25675.2 hm2, 15995.2 hm2 from 1999 to 2005 respectively. The area of forestry, orchard (vegetable garden), the industry and mining, traffic increased remarkably, and the orchard increased by 79.2% from 1999 to 2005.(4)The changes of Ansai County's land utilization have also had remarkable influence on the local economic development. Along with the adjustment of land use structure, the original agricultural population flows into the industry and the tertiary industry. The population proportion which was engaged in the agriculture in Ansai County reduced by 20% from 1989 to 2004. The vegetables greenhouses have already become the supporting industry of farmer income. During the last more than 10 years, 30,000 greenhouses, were inceased which has become the biggest big vegetables awning production county and non-environmental damage vegetables production base of Shaanxi Province. Up to the end of June, 2006, the county has produced 92,000t fresh vegetables; the output value amounted to 125 million Yuan which occupied above 70% of the total agricultural output value.(5)The changes of Ansai County's land utilization have been influenced by economy, policy, science and technology. The function of industry fostering, the driving function of town, the transferring of the city's non-agriculture direction and so on all displayed obvious positive effect in the process of Ansai's social economy development and land utilization changes. The development of oil industry impels the increase of local industry and traffic land. The progress of agricultural science and the development of agricultural and subsidiary products market have led the development of vegetables greenhouses as well as the economy forest. The implementations of"Cropland Conversion to Forest and Grass"project have sped up the rapid increase of forest land area and the fast reduction of Sloping Fields.