Global Administrative Unit Layers (GAUL)
Encyclopedia
The Global Administrative Unit Layers (GAUL) is a spatial database of the administrative units for all the countries
in the world. It is a project of the Food and Agriculture Organization
(FAO) of the United Nations
.
in the world, thereby contributing to the standardization of the spatial dataset representing administrative units. In this framework, its purposes are:
format) with a unified coding system at the levels of country, first administrative (e.g. regions), and second administrative (e.g. districts). In addition, when data is available, it provides layers on a country-by-country basis down to third, fourth and lower levels. The target beneficiary of the GAUL data is the UN community, the Universities and other authorized international and national institutions/agencies. Data might not be officially validated by authoritative national sources and can not be distributed to the general public. A disclaimer should always accompany any use of the GAUL data.
Because the GAUL works at global level, controversial boundaries
can not be ignored. The approach of the GAUL is to maintain disputed
areas in such a way to preserve national integrity for all disputing countries.
The coastline of the GAUL is mostly compliant with the coast of the International Boundary map delivered by the UN Cartographic Section except for some countries (e.g. Viet Nam, India
, Bangladesh
, etc.) where it has been updated according to the satellite images (e.g. Landsat
ETM). For future releases of the GAUL, the process of updating the coastline will go on, country by country, through a comparison with the satellite images.
The GAUL keeps track of administrative units that have been changed, added, or deleted in the past. Changes implemented in different years are recorded in the GAUL on different layers. For this reason the GAUL product is not a single layer but a group of layers, named “GAUL Set”. The GAUL project does not implement changes dated before 1990.
GAUL codes are numeric and unique for all administrative units at any of the administrative hierarchical level. Any GAUL code is independent from the codes of its higher administrative levels. GAUL codes assigned to administrative units of a given country are not necessarily sequential numbers. The main benefit of the GAUL Coding System is that changing in the codes of an administrative unit might not imply a change of codes of the correspondent units at lower levels. This means that the effort to maintain the links between thematic data and associated administrative units is reduced to a minimum.
The GAUL has a consistent framework for the delivery of the data. Once a year, an updated version of the GAUL set is released through Geonetwork. A new version includes all updates made in the course of the previous year. The dataset is free of charge and it can be downloaded by login (to receive an account, just send an email to the contacts listed at the bottom of this article). The new version GAUL 2009 will be available on Geonetwork from January 2009.
Country
A country is a region legally identified as a distinct entity in political geography. A country may be an independent sovereign state or one that is occupied by another state, as a non-sovereign or formerly sovereign political division, or a geographic region associated with a previously...
in the world. It is a project of the Food and Agriculture Organization
Food and Agriculture Organization
The Food and Agriculture Organization of the United Nations is a specialised agency of the United Nations that leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate agreements and...
(FAO) of the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
.
Mission
The GAUL aims at compiling and disseminating the most reliable geographic information on administrative units for all the countriesCountry
A country is a region legally identified as a distinct entity in political geography. A country may be an independent sovereign state or one that is occupied by another state, as a non-sovereign or formerly sovereign political division, or a geographic region associated with a previously...
in the world, thereby contributing to the standardization of the spatial dataset representing administrative units. In this framework, its purposes are:
- to overcome the fragmentation of the global dataset occurring when administrative units layers are digitized on a country-by-country basis
- to keep historical track of changes occurring on the shapes and extent of the administrative units
- to promote a unified codingGeoreferenceTo georeference something means to define its existence in physical space. That is, establishing its location in terms of map projections or coordinate systems. The term is used both when establishing the relation between raster or vector images and coordinates, and when determining the spatial...
system that reduces maintenance efforts.
Characteristics
The GAUL always maintains global geographic layers (in shapefileShapefile
The Esri Shapefile or simply a shapefile is a popular geospatial vector data format for geographic information systems software. It is developed and regulated by Esri as a open specification for data interoperability among Esri and other software products.Shapefiles spatially describe geometries:...
format) with a unified coding system at the levels of country, first administrative (e.g. regions), and second administrative (e.g. districts). In addition, when data is available, it provides layers on a country-by-country basis down to third, fourth and lower levels. The target beneficiary of the GAUL data is the UN community, the Universities and other authorized international and national institutions/agencies. Data might not be officially validated by authoritative national sources and can not be distributed to the general public. A disclaimer should always accompany any use of the GAUL data.
Because the GAUL works at global level, controversial boundaries
Border
Borders define geographic boundaries of political entities or legal jurisdictions, such as governments, sovereign states, federated states and other subnational entities. Some borders—such as a state's internal administrative borders, or inter-state borders within the Schengen Area—are open and...
can not be ignored. The approach of the GAUL is to maintain disputed
Territorial dispute
A territorial dispute is a disagreement over the possession/control of land between two or more states or over the possession or control of land by a new state and occupying power after it has conquered the land from a former state no longer currently recognized by the new state.-Context and...
areas in such a way to preserve national integrity for all disputing countries.
The coastline of the GAUL is mostly compliant with the coast of the International Boundary map delivered by the UN Cartographic Section except for some countries (e.g. Viet Nam, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
, etc.) where it has been updated according to the satellite images (e.g. Landsat
Landsat program
The Landsat program is the longest running enterprise for acquisition of satellite imagery of Earth. On July 26, 1972 the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat. The most recent, Landsat 7, was launched on April 15, 1999. The instruments on the...
ETM). For future releases of the GAUL, the process of updating the coastline will go on, country by country, through a comparison with the satellite images.
The GAUL keeps track of administrative units that have been changed, added, or deleted in the past. Changes implemented in different years are recorded in the GAUL on different layers. For this reason the GAUL product is not a single layer but a group of layers, named “GAUL Set”. The GAUL project does not implement changes dated before 1990.
GAUL codes are numeric and unique for all administrative units at any of the administrative hierarchical level. Any GAUL code is independent from the codes of its higher administrative levels. GAUL codes assigned to administrative units of a given country are not necessarily sequential numbers. The main benefit of the GAUL Coding System is that changing in the codes of an administrative unit might not imply a change of codes of the correspondent units at lower levels. This means that the effort to maintain the links between thematic data and associated administrative units is reduced to a minimum.
Organization
The implementation of the GAUL initiative is based on a collaborative work among international agencies and national authorities generating and collecting spatial information on administrative units. The role of FAO is to keep this network of collaborators active, to evaluate and compile data from available sources, to establish procedures for data integration, to generate the GAUL codes and periodically to disseminate the GAUL Set. The overall methodology consists in:- collecting the best available data from most reliable sources
- establishing validation periods of the geographic features (when possible)
- adding selected data to the global layer based on the international boundaries provided by the UN Cartographic Unit
- generating codes using the GAUL Coding System
- distributing data to the users
The GAUL has a consistent framework for the delivery of the data. Once a year, an updated version of the GAUL set is released through Geonetwork. A new version includes all updates made in the course of the previous year. The dataset is free of charge and it can be downloaded by login (to receive an account, just send an email to the contacts listed at the bottom of this article). The new version GAUL 2009 will be available on Geonetwork from January 2009.