(Henan Institute of Land Survey and Planning, Zhengzhou, 450003)
In order to establish an agricultural land grading and evaluation information system suitable for the actual needs of agricultural land grading and evaluation, improve the efficiency and accuracy of agricultural land grading and evaluation, form a unified and complete urban and rural land price system, and realize the scientific and informatization of unified land price management, through comprehensive analysis, the agricultural land valuation information system is designed and applied.
Keywords: agricultural land; Classification and evaluation; Information system; Design; App application
Compared with urban land grading and evaluation, agricultural land grading and evaluation is a new thing, involving a large number of spatial data and attribute data. If we rely on manpower to do a series of overlapping, spatial analysis and statistical calculation of these data, it is not only cumbersome but also easy to make mistakes. The establishment of agricultural land grading and evaluation information system based on GIS can greatly improve the speed and accuracy of data processing. Nowadays, computer technology is widely used, which is undoubtedly a science. According to the Regulation of Agricultural Land Classification and Evaluation issued by the Ministry of Land and Resources in 2003, combined with some problems encountered by the author in the practical work of agricultural land classification and evaluation, this paper puts forward the design idea of agricultural land classification and evaluation information system, and briefly explains the use of agricultural land classification and evaluation information system to promote the development of agricultural land classification and evaluation.
1 agricultural land grading and evaluation information system
Agricultural land grading and evaluation information system is an application subsystem of geographic information system. It uses the theory and technical methods of geographic information system, and takes computer analysis and mapping as the core, to realize the input, storage and management of questionnaires, statistical tables and sample information related to agricultural land grading and evaluation, automatically calculate the action scores of factors, automatically classify grades, display and draw relevant maps of various factors and factor scores, and finally output the factor scores calculated by agricultural land grading and sample selection.
1. 1 design principles of agricultural land grading and evaluation information system
1. 1. 1 the principle of technological innovation and giving consideration to rules.
The design of agricultural land grading and evaluation information system should follow the requirements of "Regulations on Agricultural Land Grading and Evaluation", and make full use of modern high technology, rationally apply various advanced technological achievements and related theoretical methods, so as to improve the technical level and advanced nature of the system.
1. 1.2 object-oriented principle
The latest land use status map should be used as the working base map of agricultural land grading and evaluation, which has rich spatial information. All kinds of graphic information used in agricultural land grading and evaluation are complicated. Using object-oriented technology and making full use of the encapsulation, recording and polymorphism of classes to design modules will greatly facilitate development and enhance the scalability of applications.
1. 1.3 modular design principles
Using the method of combining structure and modularization, according to the work requirements, the system is analyzed from top to bottom and divided into modules. On the basis of investigating users' needs, the user sub-modules of the system are defined, and the lowest "building blocks" are established, and then the application-oriented "upper modules" are formed through connection.
1. 1.4 consistency principle
In the process of system design and construction, we should strive for standardization, standardization and unification on the basis of existing technical regulations, and the phased implementation should be consistent with the overall planning. In addition, on the whole, the agricultural land grading and evaluation information system should be consistent in organizational form, interface style, operation mode and data interface, as well as the setting of system variables, the call of modules and the relationship between modules.
1. 1.5 application and data separation principle
In order to make the system have good portability and maintainability, in the structured organization of the system, the system program code should be separated from the graphic database and the attribute database as much as possible. The system should also provide interfaces with other databases, so that each module can run independently or be relatively integrated.
1. 1.6 Practical and safety principles
The design of agricultural land grading and evaluation information system should be "people-oriented", fully consider the business needs of agricultural land grading and evaluation by land and resources management departments, and be close to the actual work, so that the agricultural land grading and evaluation information system has powerful functions, friendly interface, simple operation and convenient use. In addition, in order to ensure the security of the data of system operation results, corresponding security measures and data backup functions should be designed.
1.2 Software and hardware configuration of agricultural land grading and evaluation information system
The hardware environment is the physical foundation of the system, and its configuration directly affects the efficiency and quality of the system. However, the hardware configuration of the system is influenced and restricted by various factors, such as the size of the system control area, the amount of data managed by the system, and the economic affordability of the system users. In order to give full play to the performance of the agricultural land grading and evaluation information system, the hardware configuration of the agricultural land grading and evaluation information system should adopt a computer with the CD burning function above P IV, and the peripheral equipment should be equipped with laser printers, A0 format engineering scanners, A0 format color inkjet plotters and other equipment.
Software is the core of system operation. Without the support of software, even the best hardware equipment can't finish the work. Generally speaking, the operating system of agricultural land grading and evaluation information system adopts general Windows system, the GIS software is based on GIS software such as Mapinfo or MAPGIS, and the relational database software can mainly be Foxpro. On this basis, the data management software can be independently developed to manage the data of agricultural land grading and evaluation, and it can be easily operated by people who are not familiar with the program design.
1.3 overall structure of agricultural land grading and evaluation information system
The system includes basic data processing subsystem, land grading subsystem and benchmark land price evaluation subsystem. The system architecture is shown in the following page.
1.4 database structure of agricultural land grading and evaluation information system
1.4. 1 basic database
(1) Worksheet Spatial Database.
(2) Spatial database of discrete point distribution.
(3) Attribute relation database of various factors.
1.4.2 process database
(1) Spatial database composed of various factors.
(2) The relational database formed by factor analysis of various factors.
Structure diagram of agricultural land grading and evaluation information system
1.4.3 results database
(1) grading results and area statistical database of various report outputs.
(2) A graphic database for drawing various scoring maps, land grade maps, benchmark land price maps, etc.
1.5 Functions of Agricultural Land Grading and Valuation Information System
1.5. 1 Function of grading module
(1) Determine the factor and the factor weight.
(2) Automatically calculate the factor as a score.
(3) Automatically generate the factor graph.
(4) Automatically generate the total score chart.
(5) Automatic land classification.
(6) Drawing land grade map and isoline map of each factor.
(7) Provide users with a revised interactive interface.
1.5.2 valuation module function
Calculation test of (1) income sample.
(2) Revise the influencing factors such as the development degree and date of plot price.
(3) Eliminate abnormal sample points.
(4) Determine the grade benchmark land price.
(5) Compile the land price correction system.
1.5.3 data processing module function
(1) generates spatial data such as ARC/INFO, MAPINFO and AUTOCAD, and attribute data such as XLS, DBF and MDB.
(2) The function of importing, exporting and editing graphics and attribute data of points, lines and surfaces.
(3) Spatial and conditional query of layer data.
(4) Realize attribute statistics of layer data.
2 Application of agricultural land grading and evaluation information system
2. 1 Establishment of graphic library of grading factors and division of grading units
Through vectorization, scanning map editing, topology and attribute database maintenance, the basic window operation functions such as zooming in, zooming out and roaming are provided, and the grading factor space and attribute database are established.
Grading unit is the basic spatial unit of grading index calculation, which requires that the land quality within the unit is relatively uniform and there are great differences between units. When agricultural land grading information system divides agricultural land grading units by superposition method or polygon method, it uses the spatial polygon superposition analysis function of GIS.
2.2 Agricultural land grading factor score calculation and grading correction coefficient calculation
According to the requirements of the Regulations on Agricultural Land Classification, there are many factors affecting agricultural land classification, such as nature, economy and society, but according to its spatial distribution law, it can be summarized into two types: one is the decreasing diffusion rate factor, such as land location factor; Second, regional homogeneity factors, such as land use and farming conditions. For the calculation of diffusion factor action score, the spatial buffer analysis method and technology of GIS are adopted. The determination of the comprehensive influence degree of each scoring factor, that is, the calculation of the total score of scoring factors, adopts the superposition analysis method and technology of GIS spatial elements.
To calculate the correction coefficient of land grading factors, GIS can be used to automatically calculate the correction coefficient of each grading factor and each grading unit according to the regional average score of grading factors.
2.3 Calculation and classification of agricultural land grading index
Using GIS, according to the selected grading factor, the correction coefficient is superimposed on the grading index layer by using the method of continuous multiplication or weighted average product, and the land grading index layer is obtained.
Using GIS system, the grading index of grading unit is statistically analyzed, and then the index boundary for judging land grade is found. According to the index boundary of dividing land grade, the grading index of grading unit is graded to generate land grade database.
2.4 Calculation of sample point and benchmark land price
Using GIS to automatically extract the land grade and grading index where the land price sample is located in the land grade database, and extract the name and code of the administrative district from the administrative district boundary database; According to the land type or land level of the sample points, the income items of the land price sample points are tested twice, and the abnormal sample points that do not meet the requirements are eliminated to generate a new land price sample point database.
According to the new sample land price database, the sample land price is automatically calculated by income reduction method, and then the benchmark land prices at all levels are calculated.
2.5 Statistical Analysis, Report Generation and Map Making
Using the multidimensional analysis function of GIS, we can complete the statistical analysis of grades and grade areas classified by villages, townships and places, and make classified summary statistics conveniently. You can also make statistical analysis on the areas of designated villages, designated towns and designated land types, and generate charts and reports corresponding to the above contents.
Using the editing and output function of GIS, all the results of agricultural land grading and evaluation can be digitized, and various results can be output as needed.
3 Agricultural land classification and valuation information system problems
After more than ten years' development, the urban land grading and evaluation information system has been widely used and practiced, and has basically matured. However, agricultural land grading and evaluation information system is a new thing that comes with agricultural land grading and evaluation, and some existing agricultural land grading and evaluation information systems are not perfect, which are mainly manifested as follows: ① some agricultural land grading and evaluation information systems are cumbersome to operate, and it is very difficult to use because of the general lack of computer knowledge in grass-roots land and resources management departments, which is not conducive to the development of agricultural land grading and evaluation update; ② Some grading and evaluation information systems need to manually input a large number of attribute data, and even some agricultural land grading and evaluation information systems can't automatically identify the sample level, which increases a lot of land price calculation workload; (3) The graphic editing function of some grading and evaluation information systems is still poor, and other GIS software is needed to edit and modify the grading and evaluation map of agricultural land and the factor action score map.
It still needs to be explored and studied seriously to establish a mature and reliable information system for agricultural land grading and evaluation, which adapts to the characteristics of agricultural land grading and evaluation, and the operation process is close to the actual needs, and faces the staff of grass-roots land and resources management departments, so that the grass-roots land and resources management staff can rely on their own strength to carry out agricultural land grading and evaluation and update. Gradually form a unified and complete urban and rural land price system, and realize the scientific and information-based unified land price management.
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Rules for agricultural land classification. Ministry of Land and Resources, 2003
Rules for agricultural land valuation. Ministry of Land and Resources, 2003
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