What is GIS

Secondary schools

History and purpose of GIS

Geographical Information System is a method of spatially storing, analysing, manipulating, managing and displaying geographical data. A GIS computer software package is as important to a cartographer as a Word Processor is to a writer.

GIS has been in existence since the late 1950s. It quickly became increasingly popular and advanced as various GIS software and organisations became established. Below is a bullet point timeline of the various GIS milestones in history.

As the purpose of GIS is to be able to analyse and relate information to its spatial location on a map, a variety of people can use GIS for their own benefit. These people would include Archaeologists, Architects, Commercial Companies, Doctors, Engineers, Historians, Law Enforcement Agencies, Meteorologists, Military, Planners, Property Developers, Politicians, and Statisticians to name but a few. The purpose of GIS is that it can relate information to its spatial location. Various factors can be incorporated into GIS analysis.

GIS contains the ability of displaying a range of features. These features could be physical like roads, rivers and urban areas.

Other features that can be illustrated on a map can be information. The map can show points on a map where there are the most accidents on our roads, the amount of people that speak Irish on a daily basis or the area which has the most increase in population since the last census was taken.

These features or layers can be placed on top of each other. These layers can be semi-transparent so that all of the layers can be seen.

Example 1:

If a person would like to establish the effect of a raincloud on the west coast of Ireland a few factors, such as the path of the raincloud, the location of mountains along its path, the state of the water-table, soil type and relief of the region, could be incorporated into the analysis.

If the saturation of the raincloud was known by meteorologists, the distance that raincloud could travel can be estimated. If there were mountains e.g the Macgillycuddy Reeks, in the path of the raincloud the precipitation would be lost quicker and therefore the raincloud would not travel as far.

The location of the mountains could be located by a contour file, DTM or Lidar.

Killarney, on the rain-shadow side of the Macgillycuddy Reeks, could have less precipitation due to the raincloud moving west to east over the mountain. The region where the rain falls would be vulnerable if the water-table was already saturated and the possibility of flooding would be estimated and modelled in the GIS software.

A DTM would be an ideal tool for spatially displaying the possible route of flood water.

This model could be animated to show the various areas that could be affected by flood water. This GIS model could be used by insurance companies to investigate the areas that would be more prone to flooding than others due the soil type and the relief which would influence where the rain water could accumulate.

Spatial information from various companies could be used with the OSi data to add more information to this example e.g. wind direction, saturation of clouds, soil and rock types.

A flood risk model could be created to see the possible affected areas with an increase in precipitation and the possible residential areas that could be affected in a 1 metre or 5 metre radius of river that is prone to flooding.

A backdrop map of the various rivers, roads, towns and residential areas can be available in either raster or vector format from OSi.

Example 2:

Another purpose of GIS would be to locate a potential site for a development such as a retail park, a hotel, a golf course or even a by-pass. The various questions that a developer may ask may include the following:

The site must be:

  • More than 5 km from national and primary roads

Roads file

  • Within 2km from regional roads

Roads file

  • Less than 500metres in height

Contour or DTM file

  • More than 5km from marsh, bog land, national parks and forestry areas.

Land Type file

  • More than 2km from local water supplies.

Waters file

  • Between 10 – 30 ha in size depending on the purpose of the site.

All of the relevant GIS files for this project are available from OSi and a project like this could be carried out for a County Development plan, Private Commercial or even for Academic purposes.

There are many more areas where GIS and OSi map files can be used. For a more specific question about the type of data you may require see our contact page.