IS GIS BREATH  OF THE GLOBE?  (Invited Article)
Dr. K.S.R.Murthy
 Assistant Professor
Remote Sensing and GIS Stream
Faculty of Science
Department of  Earth Sciences,
Addis Ababa University Addis Ababa, Ethiopia
In the present developed and developing societies in our globe Geographical Information System has become a breath, and is being used in all the fields from cycle route planning to aviation networking, modeling the natural phenomena on the earth to space modeling.

Geographical Information System, a tool in which one can store all the information about the earth surface, weather it is natural or man made.  The stored information can be modified and retrieved and obtain the answers for the questions raised by us for the welfare of the society and sustainable development of the natural resources of our earth.

What is Special about GIS

The uniqueness of GIS is its ability to store the linkage between the spatial and non spatial data and enables to retrieve and manipulate the data to find the answers to the questions on the real world. In the present society GIS is potentially used and widely accepted by the experts of different fields to manage the society and the natural resources of the earth surface. Generally the data is stored as layers in the geographic information system and once the data is stored in GIS database, it is possible to perform complex analysis.  


Applications of GIS

Though the GIS technology was primarily used to map the natural resources of the earth surface in early 60’s, now the GIS is used in interdisciplinary research.  Some of the applications are as follows;
  • Hydrogeologists and geologists use GIS for hydrological and geological mapping to find out the zones for water resources and mineral exploration.
  • Urban growth/ sprawl  can be monitored by the Urban planners
  • Business managers can use GIS technology to find out suitable areas to start new business and to improve the present business by understanding the customer location for future growth
  • Environmentalist can use GIS to monitor the Air, Water pollution and impact of forest change on environment.
  • GIS can be used in health sector to monitor the spread of a certain decease by considering different factors
  • GIS can be used in transport network to find out the shortest path from one point to the other by considering complex parameters like traffic signals, number of lanes, speed limits of the vehicle  which can be quite useful in the case of emergency
  • Police department and Social scientists can explore GIS ability to understand the crime areas in the city and the pockets of anti-social elements
Though the above are some of the applications of GIS, this powerful technology is being widely used in military applications.  It is nevertheless to say that GIS technology is being used in almost every field which has geographic relevance at any point of time.

Other potential fields in which GIS can be applied are Academic, Agriculture, Business, Environment, Natural Resource Management, Social Science, Transportation and urban planning, Water Resources and military applications.

How does a GIS work?

GIS works by relating different information in a spatial context, having the address or location reference.  When information about the rainfall is collected and stored in GIS system, it is very important to know the location or address of the rain gauge station from which the data has been collected. 

The location reference may be geographical latitude/longitude or UTM coordinates.  This rainfall information can be compared with other features like watersheds, landscape and one can infer new information weather  the  watershed and the landscape are receiving sufficient rainfall or not, which is useful for decision-making. 
Article Published on Oct. 12'2006
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Input for GIS

The main source of input for GIS analysis is Satellite data, which gives repetitive information about the same area of the earth at certain intervals.  This information can be useful to update the GIS data base frequently which helps in giving accurate results.  Other sources of data are aerial photographs, topsheets, old records and maps available with the government organizations which can be scanned and input to GIS and Global position System from which one can get the data with location accuracy.

Data Capture, Data integration, projections and integrations, data modeling and data structures are some of the important modules to be learnt and implemented for successful implementation of GIS in any field of interest.

 Information retrieval

How many number of school going children are there within the radius of 2 km of your own school? This kind of information can be retrieved easily from your GIS database by using the special retrieval function called neighborhood function.  The kind of information, How many medical shops are there within a distance of 5 km from a Hospital?  can be useful to establish a new medical shop. 

Topological modeling

Are there any gas stations near the school ? How many fire stations are there around the gas station? What is the slope, runoff and soil loss in the watershed? Answer for the above questions can be given by GIS by the module topological modeling. A GIS can recognize and analyze the spatial relationships among mapped phenomena. Conditions of adjacency (what is next to what), containment (what is enclosed by what), and proximity (how close something is to something else) can be determined with a GIS.

Networks

When there is a severe rainfall in the upstream of a catchments, it is important to understand how much time will it take to the flood to inundate the villages in the downstream of the catchments? And what is the severity of the flood?. This is done by using a linear network. It allows the computer to determine how the water is traveling to the downstream. The answers for the above questions are very useful and important to take immediate action to ejaculate dwellers in those villages under threat. The information on the volume of water, velocity of flow and speed throughout the spatial network can help the GIS determine how long it will take to travel downstream.  Network analysis can also be used to understand the shortest distance to drop the perishable goods from one place to the other. 

Overlay

The buzzing word in GIS is map overlay techniques.  Using maps of rainfall, soil, hydrogeology, geology, land use/land cover, geomorphology, and slope the GIS might produce a new map layer or overlay that ranks the given area according to their potential to explore the groundwater.

Data output

The most important and critical component of a GIS is its ability to produce graphics on the screen or on paper to convey the results of analyses to the people who make decisions about resources. One can produce more impressive and easily understandable paper maps, internet maps, interactive maps from which the decision makers can easily visualize and understand the results of the analyses performed by the expert by using GIS technology.

Now a days GIS technology is widely used to simulate the real world phenomena for sustainable development of natural resources of the Globe and GIS has become breath of the present society.

References

Chor Pang Lo, Albert K.W. Yeung, Concepts and Techniques of Geographic Information Systems (2nd Edition), Ph Series in Geographic Information Science.

www.erg.usgs.gov, Website of U.S. Department of the Interior, U.S. Geological Survey, (accessed on Oct. 11’ 2006).