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GIS or Geographical Information System is relatively new way in which geographical data is stored and managed. In the past analogue maps were used to store geographical data, but they are printed and the method of cartography is limited and it is designed to communicate spatial patterns through symbols. Raw data is not available to the map user, and the map can only display the data for which it was made. Geographical Information System is an electronic display of maps, and keeps the raw data for later use. GIS displays the data that has been selected, and can easily be switched for a different set. (Demers, 2009)
What is GIS?
GIS is the acronym for Geographical Information System which integrates hardware, software and firmware. The hardware component of GIS is the technology we use today, from the satellites orbiting the earth to the computers we use in our everyday lives. The computers contain software on which the GIS operates. This is where we input the data which is then stored by the software to be used at a later time. The firmware are the people that use the system for whatever purpose they need. GIS integrates hardware, software, and data for capturing, managing, analysing, and displaying all forms of geographically referenced data. GIS allows us to easily understand and visualize the data that was collected in the field or from maps and other sources, and to interpret and question the data which reveals relationships and patterns in the form of maps, reports, charts and globes. (Demers, 2009)
How does GIS work.
One of the important functions of GIS is the power to relate different information in a spatial context and to reach a conclusion about this relationship. Almost all information we have in geography about the world contains a location reference, placing that information at some position on the Earth. (USGS, 2007)
GIS can only use data that is in digital form. There are various techniques that can be used to capture the information and make it accessible on GIS. Maps can be digitized on a tablet that collects the coordinates of features. Coordinated from a GPS(Global Positioning System) can also be uploaded into the system. Data captures means putting the information into the system, that involves identifying the objects on the map, their absolute location on the Earth, and their spatial relationship. (USGS, 2007)
A Geographical Information System makes it possible to link, or integrate, information that is difficult to associate through any other means. Thus GIS can combine variables to build and analyse new variables which is very useful when solving problems. For example by using the GIS you can determine the amount of nutrients in streams by combining the agricultural records with the hydrography data, the total amount of pesticides/nutrients can be calculated downstream where the stream enters a lake. (USGS, 2007)
Projection and registration
Maps aren't always on the same scale or have the same projections. Map information in a GIS can be manipulated so that it registers, or fits, with information gathered from other maps and sources. Projection is a fundamental component of mapmaking. Projections are a set of techniques developed by cartographers as a means of transferring information from the Earth's 3-Dimensional, curved surface to a 2-Dimensional medium. (Demers, 2009) (USGS, 2007)
GIS is also capable of converting the structure of the data being used, because data from different sources have different structures and may not be compatible. For example the data can be stored as raster data or as vector data. Rasta data files consist of rows of uniform cell coded according to the data values. Vector digital data is captured as points, lines (a series of coordinates), or areas (shapes bounded by lines). Data restructuring can be performed by a GIS to convert data from one format to another. (USGS, 2007)
It is not possible to get information about every square meter of the Earth's surface. Data samples are taken at discrete locations. A GIS can then be used to depict 2- or 3-dimensional characteristics of the Earth's surface, subsurface, and atmosphere from points where samples have been collected. For example a GIS can quickly form isolines that indicate the rainfall from test points. Such a map can be thought of as a rainfall contour map. Two- or three-dimensional contour maps created from the surface modelling of sample points from rainfall measurements can be analysed together with any other map in a GIS covering the area. (USGS, 2007)
With a GIS you can just click on any point, object, or area on the screen and retrieve recorded information about it from off screen files. Using scanned aerial photographs as a visual guide you can ask a GIS about the geology or hydrology of the area. (USGS, 2007)
A GIS can recognize and analyse the spatial relationships among mapped phenomena. Conditions of adjacency, containment, and proximity can be determined by a GIS. This will help prevent the pollution of marsh areas as a result of a mining operation or factory. It will show that their proximity is too close to the marsh. (USGS, 2007)
Overlay is a core part of GIS analysis operation. It combines several spatial features to generate new spatial elements. Overlay can be defined as a spatial operation, which combines different geographic layers to generate new information. (USGS, 2007)
One of the most important components of GIS is the ability to produce graphics on the screen or on paper to convey the results of analyses to the people who make decisions about resources. (USGS, 2007)
GIS and Geology.
The development of GIS in geology.
The use of Geographical Information Systems technologies have increased in both number and format within specific geo-science specialities. The integration of GIS and geo-sciences has been a slow process due to preconceptions and misunderstanding between the two fields. Many geoscientists view geography as a social science. Therefore they view Geographic Information Systems as a graphic tool and not a tool for the systematic execution of complex spatial analytic functions for problem solving. GIS has been used by Geo-sciences as a storage for the increasing size of data sets rather than an analytical tool. (Hamilton, 1992)
The use of GIS in geology.
A geological map is a special map that displays the geological features of an area. Different colours are used to show the rock formations, canyons, valleys, plains, and other features of the area being mapped. With the use of a GIS these maps display areas with the maximum possible detail. Lines are used to convey the characteristics of the land, for example the height of terrain-structures. (Arun Kumar, 2010) A great deal of work has been done using computers for viewing or visualizing sensed geologic data like magnetic or gravity anomaly, or seismic data, and GIS has been readily applied to the cartographic aspects of geological mapping. GIS is mainly used as a tool for organizing, assembling and interpreting geological data, in particular field observations, measurements, and sample data, with emphasis on large scale field mapping. (T.E. Wahl, 1995)
According to (Odendaal, 2012) a geologist at the University of the Free State GIS is becoming one of the more important tools that a geologist can use. Below is an example of a geological map made with a GIS.
C:\Users\Gutser\Pictures\Simplified Geological Map of South Africa.jpg
Figure 1: Simplified Geological Map of South Africa (Geoscience, 2000)
GIS for mining
Almost all mining information has some sort of spatial component that can be presented in map form, including financial and asset information. Exploration geologists and geophysicists are presented with very diverse types of data. From hyper spectral data to simple text files, and they have to bring all the information together so it can be easily used, for this they use a GIS which can easily convert the data and display all the needed information. Geologists can now capture field data electronically using pen computers and GPS receivers. GIS aids in collecting both spatial data and tabular attributes. Existing regional maps, aerial photography, satellite imagery, or CAD drawings can be used as a backdrop to guide the field mapping. All of these sources of data can be integrated, manipulated, and analysed using GIS. Using GIS, raster data such as satellite imagery, aerial photography, gravity and magnetic data, or scanned maps can be overlaid with vector data such as faults, strike and dip measurements, geochemical samples, core hole locations, or lease and claim boundaries. (Moore, 2009)
"GIS has had an massive impact on the exploration side of mining, because exploration by definition you are wanting to look at how lots of different sets of spatially related data sets interact with each other. You may have geochemical data, geophysical data, geological map data, and topographic data and what the GIS allows you to do is to bring that together and that has revolutionized the way that exploration companies work now. Exploration can now be done a lot more quickly as well as cheaper than in the past." Said by (Bloodworth, 2011) in an interview with Mining IQ.
Sedimentary environments tend to be very complex in terms of sedimentary dynamics, and the use of GIS can help to improve understanding of the morpho-sedimentary processes, since it can provide multiple datasets analysis which is utilized in gathering, formatting and displaying large amounts of spatially and temporally related data. (Terrence McCarthy, 2005)
Geological risk factors
The analysis and identification of natural geological and geomorphological hazards associated with natural processes is a very important topic among the scientific community. In recent years different approaches have been used in assessment of the risk of geohazards, for example the mapping of selected risk factors and preparing analogue geological maps, cartographic analysis and overlaying methods using GIS. This made it easy to determine areas that are at risk, and which areas are safe from these hazards. (Juris Soms, 2011)
The potential of GIS is limited only by the potential of the people creating and furthering the development of GIS. As time passes GIS will no longer be seen as a social science or just pretty maps, it will be seen as a geographical information system that can store and manipulate large amounts of data with ease and has the ability to create new data that is essential for problem solving in the new world. GIS will be used in geology more frequently and to a greater extent than in the past. GIS will be a great help to future geologists who need to finds more scarce resources and who need to leave as small as possible impact on the environment, and accomplish this with the least expensive of ways.