The Application Of GIS In The Evaluation Of Farming Land Suitability

Land suitability evaluation is the appraisal of the suitability and its extent of land for a purpose, it is the basis for land-use decision-making and using direction ,it is also the content of the land resource research in the near past 20 years. The suitability evaluation for farming land is one of the most major content of land suitability evaluation. By grading the appropriate level of the farming land into several levels and opening out the suitability for faming land, it can provide basis for adjusting and optimizing the land-use structure and making rational land exploitation layout.This study was based on GIS and mathematical model. Taking the farming land of LongQuanyi district in ChengDu city as object ,such as plow land,garden plot and woodland, the unit of evaluation was 30m×30m raster data. According the situation of study area and the principle of factor's selection, we choice five factors such as elevation,exposure,slope gradient,source ability and traffic expedite to form the system of suitability evaluation. By virtue of the data managment of the GIS,we have established the database of suitability evaluation. On the basis of the database, we have got the special data of the evaluation factors by using GIS's Spatial Analyst: Overlay, Clustering, Digital Terrain Analysis, Buffer and so on. Application of AHP,Restrictive Ingredient and Synthesis Index technique, we have carried out the district's farming land suitability evaluation.According to analysis,the highest suitability of the three type of farming land are distributed in west plain, and the highest suitability of garden plot and woodland are also distributed in eastern hill . In the circumstance of land utilization state, 88 percent of the plow lands are suitability, only 12 percent of the plow lands are disable suitability. 99.8 percent of the garden plot are suitability, only 0.2 percent of the garden plot must adjust. There is no disable suitability woodland. On the whole, the farming land distribution of LongQuanyi is reasonable.