Short note: GIS components and sub-systems

A Geographic Information System (GIS) is a computer-based system for capturing, storing, managing, analysing and displaying spatially referenced (geographic) data.

Components

  Hardware   Software   Data   People   Methods
      \         |        |      |        /
       +---------------------------------+
       |           GIS                   |
       +---------------------------------+

1. Hardware: computers, scanners, digitisers, GPS, plotters and printers.
2. Software: GIS software (e.g. ArcGIS, QGIS) with tools for input, database management, analysis and display.
3. Data: spatial data (vector and raster) and attribute data (tables).
4. People: users, analysts and managers who design and run the system.
5. Methods (procedures): the rules and workflows for the work.

Subsystems

1. Data input (capture) subsystem: digitising, scanning, GPS, remote sensing and field data are converted into digital form.
2. Data storage and database management subsystem: stores and retrieves spatial and attribute data in a database.
3. Data manipulation and analysis subsystem: transformation, overlay, buffering, network analysis and queries.
4. Data output (display) subsystem: maps, tables, graphs and reports on screen or paper.

Applications in civil engineering

• Route selection and site suitability for roads, canals, dams and pipelines by overlay analysis.
• Urban and land use planning; cadastral and land record management.
• Utility mapping (water supply, sewer, electricity) and asset management.
• Flood, landslide and earthquake hazard mapping and disaster management.
• Watershed and water resource management; environmental impact assessment.
• Transport planning, traffic and accident analysis.