Geographic Information System (GIS) came into being in 1960s. It comes into being with the need of planning and managing natural resources and environment and the application of computer graphics technology. It is a computer system that collects, stores, manages, retrieves, processes and comprehensively analyzes a large amount of spatial data, and outputs the results in various forms. 1965, W.L.Garrison first put forward the term "geological information system", which initiated the development history of this new technology. Since then, the United States, Canada, Britain, Australia and other countries have invested a lot of manpower, material resources and financial resources, and gradually established their international leading position in this field (Huang Runqiu, 200 1).
Second, the scope of application and application examples
The application of 1 GIS technology in geological disaster information system
With the rapid growth of population, rapid economic development and massive consumption of natural resources, not only the ecological environment deteriorates, but also natural disasters (including geological disasters) occur frequently. The United States, India and other countries are countries with serious geological disasters in the world, with the characteristics of many types, wide distribution and high disaster intensity. Most of these geological disasters occur in areas with low disaster-bearing capacity, which pose a serious threat to local economic and social stability. Geological disasters are poor geological environment quality, and their frequent occurrence not only reflects the fragility of natural geological environment, but also reflects the intensification of the contradiction between human engineering economic activities and geological environment. In order to maintain the harmonious relationship between human engineering economic activities and geological environment, it is necessary to evaluate the geological environment to understand the basic situation and changing trend of regional geological environment in different economic development processes, and provide basis for environmental management and urban planning. However, traditional technical means can no longer fully cope with the rapid response of geological disasters. As the product of current high-tech development, geological information system integrates the functions of graph, image and attribute data management, processing, analysis, input and output, and should become a powerful tool for current geological environment evaluation and geological disaster prediction (Zhao Jinping, 2004).
The emergence of GIS technology is the product of the development of computer technology and information technology. It is a technical system for managing and studying spatial data. It can quickly obtain information that meets the application requirements and express the processing results in the form of maps, graphics or data (Cao Xiuding et al., 2007). Foreign countries, especially developed countries, have done a lot of work in GIS application and geological disaster research. Since the 1960s, the application of GIS technology has gradually developed from data management, digital input and graphic output of multi-source data sets to the use of DEM or DTM models, to the extended analysis of GIS combined with disaster assessment models, to the integration of GIS and decision support system (DSS), and to network GIS (Huang Runqiu, 200 1).
R. P.Gupta and B.C.Joshi( 1990) of the Department of Earth Sciences, Roorkee University, India, used the method of geographic information system to divide the landslide disaster in Ramganga watershed at the foot of Himalayan Mountain. This study is based on multi-source data sets, such as aerial photos, MSS tape data, MSS images, false color composite images and various field data, including geology, structure, topography, land use and landslide distribution. The above data need to be processed by numbers and images, and then the thematic map is interpreted and drawn, including geological map (lithology and structure), landslide distribution map, land use map and so on. Digitize these maps and store relevant data in GIS system to find out the factors related to landslide risk assessment, such as the relationship between landslide activity and lithology, the relationship between landslide activity and land use, the distribution of landslides with different slopes, the distance relationship between landslide distribution and main fault zones, etc. After statistical and empirical analysis, the landslide risk factor (LNRF) is introduced. The greater the LNRF value, the higher the risk of landslide disaster. And give three weights to the three risk levels of LNRF, which are 0, 1 and 2 respectively. Considering that the occurrence of landslide is the result of the comprehensive action of many factors, the superposition classification model of GIS is called to superimpose the weights of various factors to get a comprehensive map, which reflects the sum of the weights of various regions. According to the given standard, the risk zoning map of landslide disaster can be drawn on this map.
C J.Van Westen of ITC in the Netherlands and j b alzas Bonilla of IGAC in Colombia (1990) analyzed the geological disasters in mountainous areas based on GIS. They have done a lot of work in data collection and arrangement and established a complete database. On this basis, the slope stability analysis model and other analysis and evaluation models are developed, whose main function is to calculate the slope stability safety factor. In addition, the two scholars also developed a model to calculate the rockfall rate in mountainous areas by using the digital elevation model (DEM) generated by GIS, and drew a zoning map of rockfall rate in the study area (Huang Runqiu, 200 1).
Mario Megia-Navarro and Ellen E. Wall of Colorado State University (1994) used GIS to evaluate the geological hazards and risks in Medellin, Colombia (Jiang Zuoqin, 2008). Using GIS, the geological disasters in Medellin area are analyzed and studied, focusing on the bedrock and surface geological conditions, tectonic geological conditions, climate, topography, geomorphic units and their formation, land use, hydrological conditions and other factors. According to the composition of each factor and the corresponding relationship between disasters, each factor is subdivided into different categories and levels. With the help of GIS software (GRASS), such as spatial information storage, buffer analysis, DEM model, overlay analysis and other functions, the disaster-prone areas such as landslides, floods and river bank erosion are analyzed, and the vulnerability of each component of a specific event is evaluated.
Similarly, Mario Megia-Navarro (1996), a postdoctoral fellow at Colorado State University in the United States, combined GIS technology with decision support system (DSS), established a decision support system for natural disasters and risk assessment by using GIS (mainly GRASS software) and engineering mathematical model, and applied it in Glenwood Springs, Colorado (Jiang Zuoqin et al., 200/KLOC). The index database is established by using GIS, and the weight relationship of several control variables based on GIS is established. Carry out sensitivity analysis, vulnerability analysis and risk assessment of disasters such as mudslides, floods, land subsidence and wind disasters to assist government departments in making decisions.
At the beginning of 2 1 century, the US Geological Survey (USGS) has made it an important task to strengthen the study of urban geological disasters, and compiled digital maps of various disasters in major urban areas of the United States with the help of GIS, which is consistent with the general trend of urban geological work in western European countries. Among them, the urban geological hazard assessment project in Glenwood Spring, Colorado, USA is the most representative. Because the city is located in the mountain valley, landslide geological disasters restrict the development of the city. Therefore, the Ministry of Urban Planning commissioned Colorado State University to carry out the mapping study of GIS vulnerability and risk assessment of geological disasters. Finally, according to the land use suitability grade of 14, the land use zoning of the evaluation area is carried out, and the suitable lots and high-risk areas for future urban development are circled. On this basis, the urban comprehensive decision support system is established.
To sum up, it can be seen that foreign countries, especially developed countries, started to apply GIS to the study of geological disasters earlier (table 1), and the research degree has far surpassed ours, and the application in this field has been deepened with the development of GIS technology (Huang Runqiu, 200 1).
Application of 2.2. Geographic information system in geological and mineral exploration
Geographic Information System (GIS) has adapted to the increasing demand of modern earth and its related sciences. It is characterized by processing any massive information with spatial orientation on the earth, and has the advantages of quantification, timing and positioning. It has been widely used in geology and mineral exploration in recent 10 years. The analysis of various geological data (graphics, images, words, logic and numerical values) in a region by GIS actually represents a relatively objective overall understanding of the region at this stage. At present, there are still some problems in field data collection, data database building and GIS analysis, and GIS itself has insufficient ability to solve many professional geological problems. However, the further development and perfection of GIS will surely make geological and mineral exploration enter a new digital era (Zhou Jun et al., 2002).
GIS came into being because of solving geological problems, and its embryonic form can be traced back to the 1960s. Canadian surveyor R.F.Tomlinson first put forward the term geological information system in 1963, and built the world's first geographic information system, namely Canadian Geographic Information System (CGIS), which was applied to resource management and planning. During the period of 1970 ~ 1976, the US Federal Geological Survey built more than 50 information systems and conducted comprehensive geological research. Germany built the DASCH system in 1986, and Sweden, Japan and other countries also built their own GIS. The development of GIS and the rapid development of computer science go hand in hand, mainly in the past 20 years, and it developed faster in the past 10 years (Zhou Jun et al., 2002).
Table 1 application of foreign GIS in the study of geological environment and geological disasters
GIS came into being because of solving geological problems, and its embryonic form can be traced back to the 1960s. Canadian surveyor R.F.Tomlinson first put forward the term geological information system in 1963, and built the world's first geographic information system, namely Canadian Geographic Information System (CGIS), which was applied to resource management and planning. During the period of 1970 ~ 1976, the US Federal Geological Survey built more than 50 information systems and conducted comprehensive geological research. Germany built the DASCH system in 1986, and Sweden, Japan and other countries also built their own GIS. The development of GIS and the rapid development of computer science go hand in hand, mainly in the past 20 years, and it developed faster in the past 10 years (Zhou Jun et al., 2002).
ArcInfo and ArcView GIS are the two most popular software packages at present, which are important products of American Esri (Institute of Environmental Systems, Inc.), and have been officially identified by many countries as the main geological information systems for land resources, geology and environment management and research. ESRI was founded in 1969. Jack and Laura Dangmond started with their usual savings of 1 100. After the hard struggle in 1970s, 198 1 launched a new ArcInfo, and 1986 launched a PC ArcInfo version. 10008.000000000061981,ESRI held its first user meeting at its headquarters in Redlands, and only 18 people attended, compared with the user meeting in 6548.
The development history of ESRI reflects the development process of GIS from scratch, from weak to strong, and rapidly growing, and also shows the huge market potential and immeasurable application value of GIS from one side.
It is reported that there are thousands of GIS software with 1995 quotation on the market at present, but those with 10 or above mainly occupy the market. In addition to ArcInfo and ArcView GIS mentioned above, other representative GIS abroad include MapInfo, ErMapper, Idrisi Endas, Erdas, Genamap, Spans, Tigris, etc.
GIS has been widely used in geological and mineral exploration, and has made many remarkable achievements. The United States, Canada and Australia used it in geological and mineral survey and mapping as early as 1985 ~ 1989. At present, Australia has begun to collect digital field geological data with laptops, establish related databases, and compile the second generation geological map with the help of ArcInfo and ArcViewGIS.
Three. sources of information
Cao Xiuding, Ruan Jun, et al. 2007. Application of GIS technology in geological disaster information system. Chinese journal of geological hazard and control,18 (3):112 ~115.
Huang Runqiu. 200 1.2 1 information technology for geological environment management and geological disaster assessment in the century. Science and technology management of land and resources, 18: 30 ~ 34.
Jiang Zuoqin. 2008. Present situation and characteristics of informatization of regional geological survey at home and abroad. Geological bulletin, 27 (7): 956 ~ 964.
Jiang Zuoqin, Zhang Minghua. 200 1. Main technologies involved in field geological data acquisition informatization and their progress. Geology of China, 28 (2): 36 ~ 42.
Zhao Jinping, Jiao Shuqiang. 2004. Research status of foreign geological environment assessment based on GIS. Journal of Nantong Institute of Technology (Natural Science Edition), 3 (2): 46 ~ 50.
Zhou Jun, Liang Yun. 2002. Geographic Information System and its application in geological and mineral exploration. Journal of Xi Institute of Technology, 24 (2): 47 ~ 50.