Study on the Application of "3S" Technology in Land Consolidation Project Management

(Land Consolidation Center of Ministry of Land and Resources, Beijing, 100035)

Land consolidation project management is a challenging work involving a wide range, strong theory and technology, which objectively needs the support of advanced scientific and technological means. As a technical means to efficiently acquire and manage spatial information, 3S technology is widely used in various fields of national economy, playing an increasingly important role, providing new ideas for strengthening the supervision of land consolidation projects and improving the scientific level of project management. The application requirements of "3S" technology in land consolidation project management are analyzed.

Keywords: "3S" technology; Land consolidation; Practice; prospect

Since the implementation of the new land management law, large-scale land consolidation has flourished throughout the country. In recent years, the Ministry of Land and Resources has been committed to the study of land consolidation policies and regulations, which has played an important role in promoting the steady development of land consolidation, promoting the dynamic balance of total cultivated land, increasing grain production, increasing farmers' income and rural development, and achieved great results. However, land consolidation is a complex systematic project, and it is a highly comprehensive work, involving many policy, theoretical and technical issues. Therefore, in theory, it is not enough to do a good job of land consolidation scientifically only by relying on rules and regulations.

The Fifth Plenary Session of the 16th CPC Central Committee deliberated and adopted the "Proposal of the Central Committee on Formulating the Eleventh Five-Year Plan for National Economic and Social Development", which issued the call of "doing a good job in land consolidation" and opened a new chapter in the development of land consolidation in China. Land consolidation is an important content and inevitable choice for building a new socialist countryside in China, with great responsibility, glorious mission and broad prospects. Under the new situation, in order to promote land consolidation more quickly and steadily, it is necessary to increase the application research of high technology, establish a relatively perfect technical support system, and improve the scientific and technological content of land consolidation. Among them, the active popularization and application of "3S" technology is of great significance to improve the scientific level of land consolidation, and it is the focus of high-tech application research at present and in the future.

Analysis on the application demand of1"3s" technology in land consolidation project management

Land consolidation projects contain a lot of geo-spatial information, such as the geographical location, slope distribution, elevation change and feature distribution of the project area. Correctly interpreting these spatial information is the basis of making scientific judgment on the project. Generally speaking, there are two technical difficulties in explaining a project by conventional means: first, the existing project information carrier cannot provide enough valuable information; Second, the means of processing and interpreting information are not advanced enough, which leads to some important information being omitted or not understood. As an efficient means of information collection, processing and analysis, "3S" technology can help identify the true face of the project, monitor the "moisture" of the project, make the project decision more scientific and timely, and provide a new idea for strengthening project supervision and improving the scientific level of project management. Among them, remote sensing (RS) technology can quickly obtain all kinds of ground object information in the engineering area, and it is the main means of collecting ground object information. Global Positioning System (GPS) can be used to quickly locate important features and assist in field reconnaissance. Laser technology combined with GPS technology can quickly and accurately collect the three-dimensional spatial information of the engineering area; Geographic Information System (GIS) can carry out comprehensive processing, integrated management and various spatial analysis on multi-source spatial data to assist project decision-making.

In the preliminary preparation stage of land consolidation project, the "3S" technology can be used in basic technical work such as land consolidation potential investigation, land inventory, topographic mapping and aided design to improve the quality and efficiency of the preliminary work. From the perspective of project supervision, the application of "3S" technology runs through the whole process from project evaluation and review, supervision and inspection, completion acceptance to post-project evaluation.

In the stage of project evaluation and review, to make a scientific judgment on a project, at least three questions need to be answered: First, the authenticity of the project, such as whether the geographical location of the project area is correct, whether the declared land use type is consistent with the field, and whether it has the basic conditions such as roads, water and electricity necessary for project implementation; Second, the accuracy of basic data, such as the accuracy of the declared construction scale, the accuracy of all kinds of land use areas, and the accuracy of the calculation of new cultivated land potential; The third is the rationality of the basic technical scheme, such as whether the engineering layout of ditches, roads, forests and canals conforms to the actual terrain and whether the land leveling scheme is reasonable. To answer these questions, it is not enough to study only the project application materials. "3S" technology provides practical solutions to these problems.

In the project implementation management stage, in order to know the project implementation progress in time and prevent problems before they happen, it is necessary to track the project implementation process and monitor whether the project is built according to the expected progress and planned design scheme. The "3S" technology has been widely used in various fields of land and resources monitoring, and will surely become the most practical and efficient auxiliary tool for dynamic monitoring of land consolidation projects. The combination of "3S" technology and on-site inspection in the project area can be used as a daily means of dynamic monitoring of the project.

In the stage of project completion acceptance, the main contents of acceptance include the use of funds and the completion of engineering tasks, and the completion of engineering tasks needs to be evaluated from the perspectives of engineering quantity and engineering quality. In addition to qualitative evaluation of the project results, it is more important to conduct quantitative acceptance to see how many construction tasks have been completed and improve the credibility of statistical data. In order to obtain these data, it is unrealistic to take manual measurement in the field, and we can use "3S" technology.

Land consolidation should resolutely put an end to the phenomenon of "emphasizing construction over management" and do a good job in the management and protection of construction achievements. By regularly obtaining the latest remote sensing images of the project area, we can directly analyze the current situation of land use in the project area and whether the farmland infrastructure has been destroyed. By comparing the images of different stages before and after, the purpose of monitoring the operation and management of project results is achieved.

To sum up, the core problem of the application of "3S" technology in land consolidation project supervision is the acquisition and analysis of remote sensing data in the project area. Therefore, the resolution and application cost of remote sensing images have become the focus of the application research of "3S" technology.

2 "3S" technology in the practice of land consolidation project management

Since 200 1 National Land Development and Consolidation Project Management Training Course put forward the concept of land consolidation informatization, the application of "3 S" technology has been put on the agenda gradually, and has been paid more and more attention by the industry. This paper focuses on the application of information technology with "3S" technology as the core in all stages of land consolidation project management, aiming at exploring an advanced means to assist land consolidation project management, improving project decision-making level and realizing dynamic monitoring of project implementation process and project completion acceptance. The research results are of great significance to promote the standardized and scientific management of land consolidation projects.

2. 1 experimental data

The remote sensing image data of five experimental areas, Beixiaoying Town in Shunyi District, Changshou Town in Fangshan District, Xihongmen in Haidian District and Sujiatai District, were selected for research. The selected experimental area covers two types of landforms: plains and hills, and three types of land use: agricultural land, construction land and unused land, so it is representative. From the perspective of image resolution, it covers all kinds of resolution, panchromatic and multispectral remote sensing image data from 10 m, 5.8 m, 2.5 m, 1 m to 0.6 1 m, so as to compare and analyze the application effects of different resolution images and put forward reasonable suggestions for different application objectives.

According to the conclusion of the first stage study, the second stage study selected IKONOS 1m panchromatic image data to monitor and evaluate three national investment projects, including Huangshi Town Land Consolidation Project in Licheng District, Putian City, Fujian Province, Jugezhuang Town Land Consolidation Project in Miyun County, Beijing, and yingshan county Land Consolidation Project in Hubei Province.

In the third stage, the application of IKONOS stereo image pair in large-scale mapping and the rapid mapping system combining GPS and laser are mainly carried out. IKONOS stereo image should have a certain coverage area for the application experimental area, covering a variety of landform types and at least two bands of image data, so the border area of Shijingshan Mentougou, which has various landform types and combines mountainous areas with urban areas, is selected as the experimental area. The experimental area covers 9 topographic maps of 1∶ 10000, covering an area of nearly 240km2, including 2 band images and 4 stereo image pairs.

2.2 Research conclusion

After four years of in-depth research, the following conclusions are drawn:

(1) The monitoring of land consolidation projects requires that the geometric resolution of remote sensing images should be no less than 2.5m From the perspective of image resolution, high-resolution satellite images such as 1 m color IKONOS and 0.6 1 mQuickBird are the best choices at present. By interpreting the high-resolution images, the boundaries of various categories in the project area can be clearly drawn, the areas of various categories can be counted more accurately (according to the experimental results of this project, the error of area interpretation is within 3%), the agricultural infrastructure such as farmland water conservancy, rural roads and shelterbelts in the project area can be clearly identified, and the real situation of the project area can be fully reflected.

(2) "3S" technology can be used as an auxiliary means of land consolidation project management, helping managers to obtain real and accurate project information and make scientific judgments on the project.

By interpreting the remote sensing images of the project area, the authenticity and accuracy of the project application information can be reflected. Therefore, the "3S" technology can assist the project examiner to grasp the real situation of the project, avoid the phenomenon of false projects and repeated application for project funds, and improve the examiner's ability to identify the authenticity of the project.

By superimposing the remote sensing image of the project area with the DEM model, a three-dimensional image map of the project area can be constructed, so as to analyze the landform characteristics, slope aspect, land use type and infrastructure distribution of the project. Using visual flight technology, the project area can be observed intuitively, dynamically, from multiple angles and in all directions, and displayed, queried and analyzed in a simulated three-dimensional environment. Superimposing the engineering planning map with the three-dimensional image map can check whether the planning and design scheme conforms to the field situation and can also assist in checking the engineering quantity. This superposition analysis of different data sources can improve the efficiency of project evaluation and the ability of reviewers to judge the rationality and feasibility of the project.

Using "3S" technology, we can interpret the remote sensing images at different stages in the project implementation process and compare them before and after, so that we can dynamically monitor whether the project is carried out according to the design, construction and progress, and know the progress of the project implementation in real time.

Using "3S" technology can realize the quantitative evaluation after the completion of the project, confirm the completion of the project task, check the authenticity of the data reported by the project implementation unit, and identify the false components in the project quantity, thus making the completion acceptance quantitative and scientific.

By comparing and analyzing the images before and after the implementation of the project, the actual newly-increased cultivated land area can also be calculated to assist the project impact assessment.

(3) By analyzing the mapping accuracy (three-dimensional information acquisition) of IKONOS satellite stereo images, it is considered that the vector mapping of 1∶5000 and1∶/0000 can be completely met on the premise of having control points; The orientation without control points can basically meet the measurement needs of linear objects on 1∶ 10000 map. By analyzing the mapping cost of IKONOS satellite stereo images, it is considered that compared with the traditional field investigation and aerial photogrammetry, both indoor and outdoor work can obviously save the workload and mapping cost. Therefore, it is a feasible method to use high-resolution satellite stereo images for mapping. With the rapid development of remote sensing technology, mapping with satellite stereo images will be an important development trend.

(4) The availability of remote sensing image data is still limited. First, the data acquisition cycle is long. Remote sensing data is divided into archive data and programming data. Archived data generally does not exceed 1 month from ordering to receiving data, but archived data is mainly concentrated in cities. Programming materials need to be booked in advance, and it usually takes 3 ~ 4 months from booking to receiving the materials. Second, it is greatly influenced by climatic conditions. The best time for remote sensing images is in late spring and early autumn, and farmland crops have basically covered the ground, so it is easy to identify farmland. Rain and heat are in the same period in most parts of China, which is usually rainy, which is not conducive to shooting by visible light remote sensing camera. Usually, 20% of a scene image is covered by clouds, so it is considered that this image cannot be used to distinguish objects on the ground. The areas that are greatly influenced by climatic conditions in China are mainly the south and southwest. The rapid development of remote sensing technology is expected to solve the defects of data acquisition. For example, the Ikonos Block-II dual-star dual-resolution satellite system, with resolutions of 0.47m and 0.27m, has the same product type and delivery mode as Block-I, but its data acquisition capability, technology and efficiency will be greatly improved. Ikonos Block-III satellite system, which will be launched in 2007, is a synthetic aperture radar satellite, which can collect data around the clock and make up for the deficiency of visible light remote sensing. The resolution of the lower point of the satellite is1m. The newly developed unmanned airship remote sensing monitoring system in China closely combines unmanned airship technology with remote sensing technology, which can quickly obtain high-resolution images of the surface, has low cost and flexible operation, and is especially suitable for rainy areas with changeable climate, complex geological conditions and landform environment.

(5) In view of the high application cost of remote sensing images, especially high-resolution images, in order to reduce the supervision cost of land consolidation projects, different schemes can be adopted according to different project management objectives. Without remote sensing technology, we can do a lot of work and play a great role.

GIS application scheme: GIS has been widely used in the design, review and daily management of land consolidation projects. From the point of view of project audit, only using GIS can at least accomplish the following tasks: First, recalculate the project area scale and various land use types according to the vector data of the project status map (assuming that the application materials are true) to verify the accuracy of the application data. Secondly, according to the vector data of the project planning diagram, the content and quantity of the project are counted again to verify whether there is a problem of falsely reporting the engineering quantity. Thirdly, based on the topographic map of the project area, the DEM model of the project area is constructed. After being superimposed with the vector planning map, it can help to analyze the geomorphological characteristics of the project area and judge whether the layout scheme of the site plot, ditch, road and forest canal is reasonable and feasible. According to the site layout scheme and design elevation, it can be judged whether the earthwork calculation is reasonable and accurate. The research results show that using GIS can improve the efficiency of earthwork calculation.

GPS application scheme: The application of GPS in land consolidation project management is mainly reflected in its positioning function, which can be used as an auxiliary tool for field reconnaissance, positioning analysis and identification of the authenticity of declared data. GPS can also be used to measure the land area under simple terrain conditions.

3. Strategic conception of building "3S" technical support system

To sum up, the application research results of "3S" technology in various stages of land consolidation project management in recent years show that "3S" technology is an effective means to improve the quality of project decision-making, strengthen project supervision and improve the work level and efficiency of the industry. In the future, we should further study and gradually build a mature "3S" technical support system on the basis of increasing the popularization and application of existing research results. The system structure is as follows:

(1) rapid mapping system mapping is a basic technical work that must be carried out before the planning and design of land consolidation projects. At present, the commonly used mapping methods are generally inefficient and costly, so it is necessary to develop a fully digital three-dimensional information collection mapping system which can meet the accuracy requirements of land consolidation planning and design, has low cost, is convenient to use and has popularization and application value in the field of land consolidation. At present, the Land Consolidation Center of the Ministry of Land and Resources and the Precision Agriculture Research Center of China Agricultural University are cooperating to develop a rapid mapping system based on laser and GPS technology, which uses GPS to collect two-dimensional coordinate information and laser to collect elevation information.

(2) Three-dimensional decision-making system of land consolidation The "decision-making" mentioned here refers to the decision-making in all aspects of project management. At present, the planning and design, project evaluation, achievement display and experience exchange of land consolidation projects are all based on the traditional two-dimensional plane decision-making model. By establishing this system, the mathematical model of business processing can be established and the intelligent level of project decision-making can be improved. The latest GIS technology, 3D modeling technology and image processing technology can be used to realize 3D aided design, so that designers can directly realize their own planning ideas in 3D visual scenes. Three-dimensional spatial analysis technology can carry out slope analysis, earthwork calculation, surface area calculation, engineering content and engineering quantity statistics, spatial query and so on. Three-dimensional scene, simulated flight and multimedia technology can be used to provide intuitive on-site display means for project evaluation, decision-making and achievement reporting. , you can get better results than on-site reconnaissance; A comprehensive data management platform for land consolidation can be established to realize the integrated and systematic management of graphics, image data, text data and multimedia data.

(3) The establishment of remote sensing image database of land consolidation project is the basis and key of the application of "3S" technology. The built image database should meet the needs of monitoring and evaluation of land consolidation projects, so it needs to be updated regularly to realize resource sharing. Through the establishment of remote sensing image database, it is mainly used in two aspects: first, it is used for pre-project verification and evaluation; The second is for the supervision and inspection of project implementation.

(4)GPS-assisted field investigation system After years of research, the application idea of remote sensing technology has been relatively mature, and the application effect is remarkable. However, due to various conditions, the application of remote sensing technology still has great limitations. In practical work, we often go to the project area for field visits. However, there are also many difficulties in site exploration, especially in hilly and mountainous areas with complex terrain, and it is difficult to achieve the expected results. Therefore, it is urgent to develop a GPS-assisted field investigation system. The core goal is to integrate PDA technology and GPS technology, import engineering vector map into PDA, use GPS positioning and navigation function to realize the linkage between map and field, guide investigators to carry out field investigation and field information collection, and improve the quality and efficiency of investigation. The GPS-aided field investigation system has a broad application prospect in the preliminary verification and implementation supervision and inspection of land consolidation projects. With this system, it is equivalent to establishing a three-dimensional supervision system of "looking from the sky and checking on the ground", which will greatly improve the supervision ability of land and resources management departments at all levels.

(5) The comprehensive knowledge base of national land consolidation comprehensive knowledge base includes basic data such as nature, resource conditions, agrometeorological data, hydrogeological data and soil data, as well as relevant plans, policies, regulations and technical specifications. The establishment of comprehensive knowledge base is the basis for further improving the decision-making level of land consolidation.

Constructing "3S" technical support system is an urgent need for current land consolidation project management, and it is also the development direction of future land consolidation decision-making, which is of great significance for promoting the sustainable development of land consolidation.

refer to

, Jia, Chen Yuan, etc. Construction of land consolidation project management and decision support system. Journal of Agricultural Engineering, 2002, 18 (3)

Jia, Zhu Dehai, Yang. Discussion on the application of "3S" technology in returning farmland to forest (grass) in western China. Proceedings of the 6th Annual Meeting of China Geographic Information Association, 200 1.3.