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Modus Operandi

En librairie

Transformation de conflit, de Karine Gatelier, Claske Dijkema et Herrick Mouafo

Aux Éditions Charles Léopold Mayer (ECLM)


Fiche de notion

, Grenoble, 2013

Geographic Information System

What is GIS?

GIS stands for Geographic Information System and is a computer based System to capture, manage, analyze and displaying spatial data (ESRI 2013). With GIS it is possible to understand, question, analyse and interpret spatial data in different relationships. Moreover, it is possible to visualize the data in different forms of maps. Furthermore, GIS is a very helpful data management tool, where a geodatabase is used. The difference with other data management tools is that different datasets are combined with spatial data. A geo-database contains different thematic layers, images and data files.

Geographical data are stored in two different types – Raster and Vector Data. Vector data is object - based and raster data field-based. In the vector format exist three main object classes – points, lines and polygons. Points are 0-dimensional and an example is points of interest. An example for lines is streets, which are 1-dimensional. Polygons are areas, which mean that they are 2-dimensional. Vector datasets are clearly defined and are often linked to attributes and coordinates. For instance, the name and the length of a street are allocated to a specific line. A Raster is a matrix of cells (pixels) organized in a grid. A specific value per cell represents the information, like temperature or elevation. Rasters are for instance aerial photos, satellite images, digital pictures or scanned maps (ESRI 2008). The most popular GIS – program is ArcGIS produced by ESRI. Other GIS –software are IDRISI, MAPInfo, Geomedia, Manifold GIS, Autodesk Map, Microstation Geographics and Smallworld. But it is also possible to find open source software in the internet. Some examples are SAGA, Quantum GIS, JUMP, GRASS and many others.

The importance of maps

“Maps are more than pieces of paper. They are stories, conversations, lives and songs lived out in a place and are inseparable from the political and cultural contexts in which they are used.” (WARREN 2004)

What is the use of maps?

Since a long time maps are playing an important role. The old Greeks and the Romans were using maps as well the Egyptians in earlier times to navigate. Today the whole world is mapped. Some areas are very detailed (large scale) and other areas very sketchy (small scale). Maps are used to navigate, to get information or to make spatial analysis. Many people are using online-maps, like Google-maps, to get information or to discover interesting places. Maps are an interface between spatial planners and a complex reality. One image tells more than 1000 words. With maps it is possible to get a quick overview of the environment and its needs in terms of development. Geographical Information System (GIS) is the best tool to create maps and facilitates spatial analysis.

Why is mapping and geographical knowledge an upcoming tool in the developing context?

Many regions in the developing world are not mapped, because of non-existent knowledge and a lack of technical infrastructure. When a government or donor organizations decide to invest in development, analysis and mapping of problems in a specific area is an important first step. For example, while urban water supply in Kenya is a problem, not all areas face similar challenges. Areas in the North for example suffer from a lack of water, whereas in big cities like Nairobi and Mombasa, water quality is the issue. Moreover, coastal areas have to deal with salt water intrusion.

For the localisation of social problems maps can also be useful. Social problems in relation to water supply could for example the link between bad water infrastructure and illiteracy rate. If it takes a lot of time to fetch, water many children have to help instead of visiting a school. With the help of a GIS this could be analysed.

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