Study Of Land Suitability Evaluation Systems Base On GIS

Suitability of the land is a certain type of land designated for the appropriate level.Suitability of the land classification process is in accordance with the specific purpose of the appropriateness to evaluate and classify the land of specific areas.Geographic Information System(GIS) is new cross-discipline of geography and computer science.We apply the Geographic Information System(GIS) to the agriculture,especially in land evaluation.GIS provide the decision-making and scientific basis for the reasonable use of the land and the need for the development of modern agriculture.In recent years,GIS is more and more widely used in land resource evaluation.In our country,there are some land suitability evaluation systems which use the GIS technology.These systems use GIS software to display the spatial data and analysis or calculate,however,they can not combine the evaluation and geographic information to a whole integration.In other words,the existing evaluation systems are not real automation and professional land suitability evaluation system.They depend on the GIS software platform to achieve the evaluation function and can be operated only by the professional persons.The thesis Based on the domestic and external GIS-based land suitability evaluation system,the mathematical model,with secondary development of geographic information system technology,database technology,as well as advanced methods for evaluation,according to the actual situation of the region and the purpose of the evaluation to establish an appropriate evaluation system model.The system will achieve the purpose of the evaluation in accordance with the steps of evaluation and the model.Establishment of an appropriate evaluation system will not only integrated spatial data and attribute data which be concerned with the evaluation of the land,but also can be flexible combine the different geographic information to analysis and processing the data,thus greatly improve the efficiency and precision of land suitability evaluation.Following are the main modules of the system:1.Display and operation module.This module can browse and query the map,including the map to zoom, move,the entire display and click query.2.Data Management Module.This module includes the graphic and attribute data management,such as adding,preserving,saving and deleting the map,as well as open the attribute table,the modification and preservation of the attribute data.3.Spatial Analysis Module.This module achieves the function of spatial overlaying and interpolating the sampling point to raster.When tow vector layers overlaying,the attribute table of them will connect automatically.Spatial Interpolation achieves to estimate the characteristics of consequent area with discrete data point.4.Suitability evaluation module is the heart of system.The steps and method of suitability evaluation was acted by the program of system.Suitability evaluation module main complete AHP algorithm,frame the database of membership function and standard the data.The ultimate goal is that render appropriate grades and reflect the result on the map.5.Thematic maps output module output the results,user can printout the map by their needs and preference. These modules are combined according to the function circuit of systems and become an independent and comprehensive land suitability evaluation system.We use Access database and ADO integrated develop technique to establish and manage the technical function model library,use GIS secondary developed component-ArcGIS Engine as the develop platform,as well as use VB6.0 as the integrated developed tool of system.The system divide the type of land suitability according to the method of "Land Evaluation Program" and actual situation of the study area.It gets arable land suitability,woodland suitability and orchard suitability of Jiutai city's land resources.