General Introduction to Geographic Information Systems (GIS)General Introduction to Geographic Information Systems (GIS)

By Sylvanus Abua

Introduction
It is assumed that most of us present here have heard of geographical information systems (GIS) and may even have seen one or two demonstrations or the paper output they produce.

We hope that through this Workshop, participants will gain a better understanding of what GIS is and what it can do. The Workshop is therefore designed to explain and describe key aspects of GIS and its potential applications.

Considering the length of time we will spend here, we will concentrate on areas that enable you make sense of the applications of GIS and understand what is required to set up and implement your own GIS project.

Defining GIS
No one has yet found a definition that satisfies everyone. The definitions of GIS depend on who is giving it, and their background and viewpoint. Essentially, scholars and practitioners view GIS from three approaches: tool box approach, organisation-based approach and database system approach.

Scholars who perceive GIS as a tool box, offer definitions similar to the one below:
‘GIS is a powerful set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world’ (Burrough, 1996).
Following the institutional approach, Cowen (1988) states:
GIS is a decision-support system involving the integration of spatially referenced data in a problem- solving environment’.
A definition offered by Aronoff (1989) reflects the opinion by those who picture GIS as a database system. According to Aronoff (1989):
‘GIS is any manual or computer based set of procedures used to store and manipulate geographically referenced data’
The definition offered by Cowen is most essential for this enlightenment workshop. We will refer to this definition from time to time.

In general, the definitions of GIS cover three main components. First, the definitions tell us that a GIS is a computer-based system. Secondly, they tell us that GIS uses spatially referenced data. Thirdly, GIS carries out various management and analysis tasks on these data. A session on the GIS process, which comes up tomorrow will elaborate on this point

Why GIS Matters
GISs allow quick and easy access to large volumes of data. It has powerful output capabilities (maps, graphs, and summary statistics) tailored to meet particular needs.

Imagine that we were in the early 1960s, and that we are part of a team working for the national department of natural resources and development for a large country. Among our main duties in managing the resources in our area is to inventory all the available forest and mineral resources, wildlife habitat



requirements, and water availability and quality. Beyond just a simple inventory however, we are also expected to evaluate how these resources are currently being exploited, which are in short supply and which are readily available for exploitation. In addition, we are expected to predict how the availability and quality of these resources will change in the next 10, 20, or even 100 years.

All of these tasks must be performed so that you and your superiors will be able to develop a plan to manage this resource base so that both the renewable and non-renewable resources remain available in sufficient supply for future generations without seriously damaging the environment. You have to keep in mind, however, that exploitation of resources frequently conflicts with the quality of life for people living in or near the areas to be exploited, because noise, dust, scenic disturbances may be produced that impact the physical or emotional health of local residents, or devalue their property by creating nearby eyesores. And, of course, you must comply with local, regional and national legislation to ensure that those using the resource base also comply with the applicable regulations.

The above task is a daunting one. It requires enormous amount of data gathering, compilation, evaluation, analysis and modeling. One can address this complex problem by asking the following generic questions:

What is at…?
The first of these questions seeks to find out what exists at a particular location. A location can be described in many ways using, for example, place name, post code, plot number, or geographical reference such as latitude and longitude.

Where is it?
The second question is the converse of the first and requires spatial analysis to answer. Instead of identifying what exists at a given location, you want to find out where certain conditions are satisfied (e.g. a location with a particular soil type, lying at a certain elevation, and receiving a specified amount of rainfall).

What has changed since…?
The third question might involve both of the first two and seeks to find the difference within an area over time.

What spatial patterns exist?
This question is more sophisticated. You might ask this question to determine whether river blindness is common among residents who live close to fast flowing streams.

What if..?
“What if...” questions are posed to determine what happens, for example, if toxic substances seep into the local ground water supply. Answering this type of question requires both geographic and other information (and possibly scientific laws).



Potential areas of application of GIS
The range of applications of GIS is limitless. The tool can be adapted to meet the need of any organisation that need to process geographical data into information. Information here refers to data with meaning having text. Below is a sample of potential GIS application areas.
Agriculture
Prediction of crop yield
Monitoring and management
Environment
Monitoring
Modeling
Land evaluation and rural planning
Epidemiology and Health
Location of disease in relation to environmental factors
Forestry
Management, planning and optimizing extraction and replanting
Emergency services
Optimising fire, police, and ambulance routing
Improved understanding of crime and its location
Marketing
Site location and target groups, optimizing goods delivery
Site Evaluation and Costing
Cut and fill, computing volumes of materials
Social studies
Analysis of demographic movements and developments
Tourism
Location and management of facilities and attractions

Sample GIS applications from around the world
The first applications of GIS varied between different parts of the world, depending on the local needs. In mainland Europe, the major thrust went into building land registration systems and environmental databases. Britain’s greatest GIS expenditure in the 1980s, however, was for systems for utility companies and for the creation of a comprehensive topographic database for the whole country, mostly derived from maps at 1:1250 and 1:2500 scales.

In Canada, an important forestry application planned the volume of timber to be cut, identified access paths to the timber, and then reported the results to the provincial governments. In China and Japan, heavy emphasis has been placed on monitoring and modeling possible environmental changes

In the USA, all of these applications have been important. Another deserving special mention is the use of GIS technology in the TIGER (Topologically Integrated Geographic Encoding and Referencing) project by the U.S. Census Bureau and the U.S.Geological Survey. The project designed to facilitate taking and reporting the 1990 census, produced a computerized description of the US transportation network at a cost of about $170 million

The largest collections of geographic data yet assembled are the volumes of satellite imagery collected from space. Unlike much other (vector) geographic data, these come in raster (or grid) form; small square areas of ground area. Such data is analysed using special purpose software called image processing systems, and often on special hardware.

The most important point to note is that all these applications – land registration, utilities, forestry, environmental planning, and demography – have been carried out using similar software and techniques. Thus, a GIS is a general-purpose tool.

Components of a GIS
There is almost as much debate over the components of a GIS as there is about its definition. At the simplest level, a GIS can be viewed as a software package, the components being the various tools used to enter, manipulate, analyse and output data. At the other extreme, the components of a GIS include: the computer, system (hardware and operating system), the software, spatial data, data management, and analysis procedures and the people to operate the GIS. In addition, a GIS cannot operate in isolation from an application area, which has its own tradition of ideas and procedures.

For the purpose of this Workshop, we will adopt the more comprehensive perspective. The speaker who will handle the session on the GIS process will further elaborate on the components of a GIS.