Geographical Information System

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Geographical Information System (GIS) is a tool for analysis and presentation of spatial data. It is a collection of computer hardware, software and geographic data for capturing, managing, analysing and displaying all forms of geographically referenced information.

What is GIS?

Simple definition 
A Geographic Information System organizes large volumes of raw data into a map form for easy comprehension.
GIS divides raw data into layers so it can give you a better understanding for the whole world.

A GIS is designed for the collection, storage, and analysis of objects and phenomena where geographic location is an important characteristic or critical to the analysis - this definition is broad and applies to a wide variety of methods for storing, accessing, and manipulating geographic information; it does not limit GIS to the computer environment[1] .

Why is GIS unique?

  • GIS handles SPATIAL information
    • Information referenced by its location in space

Characteristics of a GIS

GIS stores geographic coordinate data (spatial data) and attribute data.

Spatial data:

  • represent features having known locations on earth
  • one of: points (0D), lines (1D) or areas (2D)

Attribute data:

  • non-graphic information linked to the geographical features (spatial data) describing features eg type of road, name, history.

Data formats

Two basic formats for storing and processing coordinate data: Vector and Raster


  • uses point locations (X,Y coordinate)
  • advantage: less storage space
  • disadvantage: may be more difficult to perform certain overlay functions


  • data stored as a matrix of pixels, representing points.
  • to analyse or overlay multiple data layers, the layers must share a common projection and coordinate system, and layers must have topology established
  • Disadvantage: it is necessary to store the entire matrix
  • Advantage: can perform neighbourhood analysis easily

Map data is separated and stored in layers usually based on common geographical themes or data type. And alternative is objected-oriented GIS, where geographical and all other information regarding a feature stored as an object.

GIS functions

  • Data input
  • Storage
  • Management
  • Analysis
  • Output

Data input

  • keyboard entry, digitize maps; digital scanning (like a photocopy)

Storing data using Geodatabase

  • Geodatabase is a container for spatial and non- spatial data that can be organized in a certain structure.
  • Advantages:
    • provide a single, consolidated data storage for field measurements and all types of data used.
    • Controlling data entry by applying validation rule on the attributes.

Data management

  • database management system controls the way data are stored and retrieved
  • includes verifying geographic coordinates and examining for accuracy

GIS analysis

  • create new data by manipulating existing data or analyzing relationships between sets of data
  • basic operations: retriecal, map generalization, map abstractions, map sheet manipulation, map abstractions, map sheet manipulation, buffer generation, polgygon overlay and dissolve, measurements, digital terrain analysis and network analysis (Cox and wotshisface, 1997).


  • display of output through printers and computer screens

Benefits of GIS

  • ability to integrate different databases into one environment
  • ability to display and manage spatial data in a spatial contect
  • rapid production of specialized map and graphic products
  • performs complex spatial analysis


  • GIS stores all data relevant for the CZM
  • GIS handles data on all spatial scales (North Egypt coast vs. a single harbour)
  • GIS is a powerful analysis tool.
    • Comparison of measurements from different years
    • Overlay analysis of measurements and modelling results

Coastal Zone management: GIS perspective

Data types

Dfs1 Data MIKE 21
  • DFS2 Data MIKE 21
  • Dfs1 Data MIKE 21
  • XYZ Data
  • Wave time series & Rose
  • Scanned Maps
  • CAD drawing
CAD drawing

Additional Data

  • Land use
  • Sediment classification
  • Satellite images
  • Geographical maps
  • Reports (design, licenses, Site investigation)
  • ….etc.

External links

Wikipedia: GIS

GIS WWWW resource list of servers likely to be of interest to the GIS community

GIS dictionary


  1. Cox, A., Gifford, F. An overview to geographic information systems. The Journal of Academic Librarianship, Volume 23, Issue 6, November 1997, Pages 449-461

8th January, Ulrik Lumborg and Caitlin Pilkington (, DHI.