GIS-based Farmland Gradation Reasearch

With the development of economy,the growth of the population and the fast expansion of the urban scale,the demand of land is rising rapidly and the quantity of farm land is reducing sharply,The contradiction between people and land is conspicuous day by day.In order to reasonably utilize and manage the limited land resources,realize the sustainable utilization of the land resource,guarantee the dynamic equilibrium of the total amount of farmland(especially the cultivated land),realize the dynamic balance of total amount of arable land and the lasting sound development of social economy,it's essential to evaluate the quality of farmland scientifically.In the new national survey of land resources,farmland gradation and evaluation is one of the most important parts in Land resource survey and Monitor Engineering.The job of Jilin Province was deploying under this background.Supported by the Farmland Gradation Project,this dissertation,utilizing Geographic Information System as a technical foundation and taking Fuyu county as an example,studied on the method of farmland grading in order to test the rationalization of《farmland grading regulations》and offered some practical foundations and experiences for this work which would be performed all over province.The dissertation comprises six sections:1,Chapter 1.From the background and meaning of the choice to commence,this section summarized the historical development,main problems and the development trend,expounded the necessity and feasibility of farmland gradation based on GIS emphatically,and brought forward the objective and content of the dissertation.2,Chapter 2. Theories and methods related to Farmland Gradation were discussed;concepts and functions of GIS were introduced,also including ArcGIS which is the most advanced in the word;Lastly, the technical system was introduced,including previous preparation,acquirement of data and attribute,construction of evaluation model.3,Chapter 3. Taking Fuyu county as an example,it put the theories and methods of Farmland Gradation into the practice by using the ArcGIS software,and divided the 298839.5ha farmland into 2 natural grades,5 utilizable grades,5 economic grades.Based on the correcting scheme of coefficient,farmland of Jilin Province was divided by grade type.The result is:7 natural grades,12 utilizable grades,9 economic grades.As the result,the grade value amounted to 363.63～1554.90,75.92～1198.11,13.52～883.289 respectively.4,Chapter 4.Technology and methods of thematic mapping was introduced,including the mapping platform-ArcMap and farmland gradation symbol base.Technical flow of spatial data basing was also introduced,including the concepts of Geodatabase.5,Chapter 5.Aimg at the problem of data sharing,a method based on WebGIS which will extend the applying area of farmland grading production was introduced,including the structure model based on ArcIMS.Taking FME as the platform,two research hotspots such as multi-data accessing,data distributing were discussed in this section as a new method for extending applying area.6,Chapter 6.In the section of conclusion and suggestion,the dissertation summarizes the experiences in the farmland gradating research,and put forward some suggestions for the further research.The study showed that:1,The method of the farmland grading is a scientific one,and its achievement is practical.First of all,it corrects the index of the yielding potential of plants decided by light and temperature through the factors such as soil,terrain,irrigations and so on,the revises the production of the farmland to the average conditions of utilization and economy with the land utilization coefficient and economical coefficient,and according to the above,makes the farm land grades.Therefore,this work synthetically uses the theories and methods of the using current condition appraisal,potential appraisal and suitability appraisal to the farmland,and takes the farmland using level and economical benefit into account,so the result has multi-gradation.At the same time,the achievement of the farmland grading based on GIS,is of great practicability.That is the database that GIS has set up realizes the exchange visits of graph database and property database,so that it is convenient for applying and renewing the achievement,and the achievement property database contains a great deal of soil information which is highly advantageous to know the quality condition and limited factors of every farmland appraisal unit,and also supplies some foundation on using and improving the soil condition.2,GIS supplies the technical foundation for farmland grading and improves the speed and precision of the work.Taking GIS as technical foundation and using its ability of space analysis and data processing can save the manpower,material resources and financial capacity,accelerate the work pan,also increase the achievement precision;the farmland grading achievement based on GIS can conserve all original data as well as the intermediate and end achievement that makes it convenient to revise and renew the achievement. Farmland grading project of Jilin Province will help to fill its vacancies in some important domains such as dynamic balance of total amount of arable land,primary farmland protection and so on.Supported by the project,this dissertation explored the method and process of farmland grading based on GIS,assessed the quality of Jilin Province synthetically,revealed the quantity and location scientifically.