Geographic Information System (GIS)

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.

A Geographic Information System (GIS) is a computer-based system to capture, store, manage, analyse and present geographically referenced data. It links spatial data (maps) with attribute data (tables) and allows overlay and analysis of many layers, such as terrain, soil, land use, roads and drainage.

Applications in civil engineering

• Route and site selection: overlay of slope, geology, land use and cost layers to find the best alignment of roads, canals, pipelines or the site of a dam or bridge.
• Urban planning and land use: zoning, growth monitoring, infrastructure planning, cadastral and land records.
• Water resources and hydrology: catchment delineation, drainage network and flood modelling, irrigation planning.
• Utility management: mapping and maintenance of water supply, sewer, power and telecom networks.
• Hazard and disaster management: flood, landslide and earthquake risk mapping; evacuation planning.
• Transportation: traffic and accident analysis, network and shortest path analysis.
• Environmental impact assessment of projects.
• Construction: terrain models, cut and fill estimation and project monitoring.

Photogrammetry

Photogrammetry is the science and art of obtaining reliable measurements, maps and three-dimensional information of objects and the Earth's surface from photographs, usually overlapping aerial photographs. It is used to prepare topographic maps, DEMs and orthophotos.

Application of GIS in civil engineering and mapping

A GIS stores, analyses and displays spatial data in layers.

• Mapping: digitising and storing base maps, thematic maps (land use, soil, geology) and cadastral maps; updating of maps; combination with remote sensing and photogrammetry products (orthophotos and DEMs).
• Route and site selection: overlay of terrain, land use, geology and cost layers for road, canal, pipeline, dam and bridge location.
• Urban and regional planning: land use zoning, population and growth analysis, infrastructure planning.
• Utility and asset management: water supply, sewer, power and road networks.
• Water resources: catchment and drainage analysis, flood modelling, irrigation planning.
• Disaster management: landslide, flood and earthquake hazard and risk maps; relief planning.
• Environment: impact assessment and monitoring of land cover change.
• Transportation: traffic and accident analysis, shortest path and network analysis.
• Construction: terrain models, cut-and-fill volumes and project monitoring.

A Geographic Information System (GIS) is a computer-based system for the capture, storage, management, analysis and display of spatially referenced data, linking maps with attribute information.

Why GIS is better than other mapping tools

• Integrates data from surveying, GPS, remote sensing and photogrammetry.
• Helps decision making with "what-if" analysis.

Applications

• Route and site selection, urban and land use planning, cadastral mapping.
• Utility network management, transport planning.
• Water resources, flood and landslide hazard mapping, disaster management.
• Environmental monitoring and impact assessment.