Practical Research On Farmland Grading Based On GIS

Just in this context, this paper,utilizing Geographical Information System as a technical foundation and taking planning area of Dingxi City as an example, studied on the method of farmland grading.The study showed that:1 The 118.45km~2 farmland in planning area of Dingxi City is divided into 4 grades.First grade is 25.47km~2,and takes up 21.50% of the total area;Second grade is 38.65%km~2,and takes up 32.63% of the total area;Third grade is 44.07km~2,and takes up 37.21% of the total area;Fourth grade is 10.26km~2,and takes up 8.66% of the total area.2 From the urban center to the surrounding,farmland level is decreasing.Most farmland of Bolin,Donghe,Futai,Zhongchuan is first grade,the farmland level of Kangjiazhuang and Shiping is the lowest.The second grade continuous distributes first grade external.The third grade and fourth grade continuous distribute second grade external.City center,traffic conditions and obstructions affect farmland grade.In the east of railway and highroad,the farmland grade of Chankou,Sanshilipu,Beiershilipu,Shiping is lower.3 In higher farmland grade,there is some lower farmland grade.Meanwhile,in lower farmland grade,there is some higher farmland grade.In the future,first grade,third grade and fourth grade will be relatively stable.With the development of Dingxi,the second grade will be greater improvement,and individual regions will upgrade to first grade.High-level farmland area will be expanded,low-level farmland area will be reduced.4 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 analyzing and inquiring into the achievement.5 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 plan, also increase the achievement precision; the farmland grading achievement based on GIS can conserve all original data as well as intermediate and end achievement that makes it convenient to revise and renew the achievement.Finally, this paper discussed the questions encountered in the practical test study, and put forward the following suggestion:Firstly, establishing expert system and some models, make grading factors′weight of farmland is close to their true data; Secondly, in accordance with the situation that the differences in defining of farmland grading, we need to use models of cluster analysis so that the result is objective; Thirdly, the precision of farmland grading achievement is suitable for high but not low, so that it is easy to apply.