I. Geographic information and geographic information systems
Geographic information refers to numbers, characters, images and graphs that represent the quantity, quality, distribution characteristics, interrelationships and changing laws of various elements in a geographic system. The development from geographical data to geographical information is a leap in human understanding of geographical things. The lithosphere, hydrosphere, atmosphere and human activities on the earth's surface are the largest geographical information sources. An important task of geographical science is to quickly collect geometric information, physical information and artificial information in geographical space, and identify, transform, store, transmit, regenerate, display, control and apply these information in time.
Geographic information belongs to spatial information, and its location identification is linked to data, which is the most obvious sign that geographic information is different from other types of information. This positioning feature of geographic information is to identify the spatial position through the geographic coordinates established by longitude and latitude network or highway network; Geographic information also has the characteristics of multi-dimensional structure, that is, it realizes multi-theme three-dimensional structure on the basis of two-dimensional space, and carries out the relationship between the theme entities through attribute coding, which provides the possibility for comprehensive research among the various circles of the geographic system, and is also convenient for multi-level analysis of the geographic system and information transmission and screening. The time series characteristics of geographic information are very obvious, so geographic information can be divided into ultra-short-term (such as typhoon and earthquake), short-term (such as river flood and low temperature in autumn), medium-term (such as land use and crop yield estimation), long-term (such as urbanization and soil erosion) and ultra-long-term (such as crustal change and climate change) according to the time scale. On the one hand, this dynamic change of geographic information requires that geographic information can be obtained in time and updated regularly; On the other hand, it is necessary to study its changing law from its natural change process, so as to predict geographical things and provide basis for scientific decision-making. Understanding the regional, multi-level and dynamic characteristics of geographic information is of great significance for establishing geographic information system and realizing the integration of population, resources and environment.
Geographic Information System (GIS) is a computer technology system based on geospatial database, supported by computer software and hardware, which collects, manages, operates, analyzes, simulates and displays spatial related data, provides various spatial and dynamic geographic information in time, and serves geographic research and geographic decision-making. Therefore, geographic information system has the following three characteristics:
(1) has the ability to collect, manage, analyze and output various geospatial information.
(2) For the purpose of geographical research and decision-making, it has the ability of spatial analysis, multi-factor comprehensive analysis and dynamic prediction by means of geographical model method, and can produce high-level geographical information.
(3) Spatial geographic data management is supported by computer system, which uses computer programs to simulate conventional or special geographic analysis methods, acts on spatial data, generates useful information, and completes tasks that are difficult for human beings to complete; The support of computer system is an important feature of GlS, which enables GIS to locate and dynamically analyze complex geographic systems quickly, accurately and comprehensively.
Second, the composition of geographic information system
Geographic information system is a computer technology system, which consists of basic parts such as information input, storage, data analysis and processing, and information output. , and work with the support of computer software and hardware. Various components play different roles in GIS and can be divided into five parts:
(1) Computer hardware: refers to the basic equipment required by GIS. These devices are used for storage, processing and display. The object is mainly digital map or digital image data.
(2) Computer software: including all kinds of programs and related materials required for machine operation, such as operating system, compiler, assembler, special program, GIS database management system, various analysis programs, user manuals and instructions, etc. The main function is to complete various GIS operations.
(3) Data: Various geospatial data needed for GIS research, including digitized map data, digitized image data, statistical data for analysis, etc.
(4) Process: When GIS is working, it is a step-by-step operation to get the answer to the question. When many systems are implemented, in order to facilitate users to use the directory selection method, that is, the so-called "menu" method, which action to click; Some systems also use command mode to input commands according to users' needs, which can be completed by the system. A command can do an action, or a command can complete a series of actions, which is the command process.
(5) Expert: Knowing GIS and using the system are the most important. Some systems cannot be fully understood, let alone further developed. The workload of creating GIS is very large, and "person year" is often used as the unit of measurement.
Third, the types of geographic information systems.
(1) Thematic Geographic Information System: It is a geographic information system with limited objectives and professional characteristics. Serve specific special purposes, such as water resources management information system, mineral resources information system, crop yield estimation information system, grassland resources management information system, soil erosion information system, environmental management information system, etc.
(2) Regional Geographic Information System: It mainly aims at regional comprehensive research and comprehensive information service. There can be regional information systems of different scales, such as national level, regional level or provincial level, municipal level or county level, to serve different levels of administrative regions, and regional information systems can also be established according to natural divisions or river basins. Regional information systems such as Canadian National Information System, American Oak Ridge Regional Information System, San Diego County Information System, China Yellow River Basin Information System, etc.
(3) GIS tool: it is a set of software packages with basic GIS functions such as digital graphics and images, storage management, query and retrieval, analysis and operation, and various outputs. They are either specially studied or obtained by extracting geospatial data of a specific region or topic after completing a practical geographic information system. These softwares are suitable for supporting GIS, establishing thematic or regional practical GIS, and can also be used as teaching software. Because the design technology of GIS is high, and the repeated editing of complex basic software also causes great waste of manpower, it is undoubtedly a shortcut to establish a practical GIS by using GIS tools.
Four. Geographic Information System in Resources and Environment Research
2 1 century, the cause of geographic information system in China has developed rapidly, and the role of geographic information system has been recognized by the public more and more, and it has been vigorously applied in various fields. Mankind is entering a new information age characterized by the application of information technology and space technology. Geographic Information System (GIS), as a new technical science, has become one of the most active information industries since the late 1980s. It involves GIS software, hardware, data, remote sensing and aerial photography, cartography, field data collection, data exchange, system integration and consultation. Among them, software is the technical core of GIS, and companies or institutions engaged in software development and system integration often become the main body of GIS industry.
In the early days, GIS was mainly used in automatic mapping, facility management and land information system (LIS), and then it was gradually extended to many fields such as resource and environment management, forest resources investigation, urban planning, municipal management, disaster monitoring and prediction, scientific research and military strategy. With the maturity of GIS technology, the accumulation of data and the improvement of application environment, its application scope is expanding and its application degree is deepening. The application of GIS in the study of resources and environment is mainly manifested in the following aspects:
1. Resource inventory and management
The inventory, management and analysis of resources are mature and important fields in GIS application, including the inventory and management of land resources, forest resources and mineral resources, land use planning, wildlife protection and so on. Resource inventory is the most basic function of geographic information system. At this time, the main task of the system is to collect data from various sources, and provide regional resource statistics and resource status analysis of various combinations according to various boundary and attribute conditions through the statistical and coverage analysis functions of the system, thus providing a basis for rational development and utilization of resources and scientific management.
Taking land use types as an example, the distribution and area of different land types, land use types divided by different elevation zones, land use status in different slope areas, land use differences caused by different lithology and land use changes in different periods can be output, which provides a basis for rational utilization, development and scientific management of resources. Another example is the land and resources information system in southwest China, which has three functional subsystems, namely, database system, auxiliary decision-making system and graphic system. More than 3 million items 1500 are stored in the resource data. The system provides a series of resource analysis and evaluation models, resource prediction and rational development and allocation for southwest China. Professional maps with different contents such as grassland resources distribution map, mineral resources distribution map, county output value statistical map, crop output statistical map, traffic planning map and major project planning map can be drawn.
2. Regional and town planning
Urban and regional planning needs to deal with many problems of different nature and characteristics, involving many geographical variables and a large amount of data such as resources, environment, population, transportation, economy, education, culture and finance. The database management of geographic information system is conducive to the integration of these data into a unified system, and ultimately the multi-objective development planning of cities and regions, including urban master planning, urban construction land suitability evaluation, environmental quality evaluation, road traffic planning, public facilities configuration, urban environmental dynamic monitoring and so on. The spatial search method, multi-information superposition processing, spatial analysis method and network analysis function of GIS provide guarantee for the realization of these planning functions. There are many large and medium cities in China. According to the requirements of accelerating the planning and construction of central cities and strengthening the scientific and modern decision-making of urban construction, it is of great significance to use GIS as a tool for urban planning, management and analysis.
3. Environmental disaster monitoring
Using GIS method and multi-temporal remote sensing data can be effectively used for forest fire prediction, flood disaster monitoring and disaster loss estimation, providing timely and accurate information for disaster relief and flood control decision-making. For example, according to the research of Daxinganling region in China, through the survey and analysis of forest fires, hundreds of thousands of meteorological data were statistically analyzed. The meteorological factors such as air temperature, wind speed, precipitation, air temperature, vegetation growth in spring and autumn, snow cover and other factors 14 were screened out, and the mathematical model was established by fuzzy mathematics method, and the multi-factor comprehensive index forest fire risk prediction method of microcomputer information system was established. The accuracy of fire risk grade prediction can reach more than 73%. Another example is the Yellow River Delta flood control and disaster reduction information system. With the support of ARC/INFO geographic information system software, with the help of large-scale digital elevation model and various thematic maps, such as land use, water system, residential areas, oil wells, factory sewage facilities and socio-economic statistical information. Through graphic superposition, calculation, analysis and other functions, several flood discharge areas and their areas can be calculated. By comparing the land use, housing and property losses in different flood discharge areas, the best flood discharge area is finally obtained, and the best transportation route for personnel evacuation, property transfer and disaster relief materials supply in the whole flood discharge area is formulated.
4. Environmental protection and management
Geographic information system technology is also a powerful tool for environmental assessment and environmental planning management. Its contents include: environmental monitoring and data collection, establishing basic database and environmental dynamic database, establishing relevant models of environmental pollution, providing statistical data and report output of environmental management, environmental impact analysis and environmental quality evaluation, environmental information transmission and mapping, etc.
Environmental management involves all fields of human social activities and economic activities. A large and medium-sized city may collect and monitor as many as 1 10,000 environmental data every year. For such a large amount of data, it should be effectively used for environmental management decisions and other purposes. The functions of a local environmental management information system are as follows: to provide the environmental management department with the storage mode of data and information system-basic database system; Provide data statistics, reports and graphic editing methods for environmental management; Establish several environmental pollution models to support environmental management decision-making; Provide office software for environmental protection departments; Provide methods and means of information transmission.
For example, Shanghai Environmental Management Information System has the following characteristics: ① A dynamic database has been established, which can store environmental monitoring data (including pollution sources and environmental quality) and other related data (such as environmental standards, hydrology, meteorology, etc. ), and for most environmental management functions, data can be shared; (2) Oriented to environmental quality management, which can provide support for statistics, evaluation, prediction and planning of environmental quality; (3) Providing support for pollution control and management oriented to pollution sources, and realizing the management of pollution charge and pollution permit system; ④ For the convenience of users, the system has designed a window menu system with friendly interface, which is easy to use and can provide different forms of output, including screen display, table printing, graphic drawing and disk output. , and reserve the remote communication interface.
5. Macro decision-making
GIS can provide a scientific basis for national or regional macro-decision through the construction and comparative analysis of a series of decision-making models by using effective databases. For example, the study of land carrying capacity supported by GIS can solve the planning of land resources and population capacity. In the study of the Three Gorges area, China has established an environmental monitoring system by using geographic information system and computer-aided mapping, which provides a reliable basis for macro-decision-making on the quantity, speed and evolution trend of environmental changes before and after the construction of the Three Gorges Reservoir. For another example, through the analysis of the data related to resources and environment such as soil erosion intensity, geological lithology and slope in the database of soil erosion monitoring system, the soil erosion can be predicted by using the graphic superposition function and the change law model, which provides a solid data foundation for the compilation of soil and water conservation planning and the implementation of ecological environment management, and provides a basis for macro-decision.