Global template for the GLASOD digital database

The Global Assessment of Human Induced Soil Degradation (GLASOD) was conducted by the International Soil Reference and Information Centre (ISRIC) at Wageningen, The Netherlands, as commissioned by the United Nations Environment Programme (UNEP). ISRIC produced a 1:10 million scale wall chart in 1990 and subsequently produced a digital data set. In essence, the GLASOD database contains information on soil degradation within map units as reported by numerous soil experts around the world through a questionnaire. It includes the type, degree, extent, cause and rate of soil degradation. From these data, the GRID-Nairobi center produced digital and hardcopy maps and made area calculations.

The GLASOD database includes a topographic basemap or global template of continental coastlines, islands and lakes, which GRID-Nairobi extracted from the digital version of GLASOD's 1:10 million wall map. All of the boundaries that defined oceans and lakes were selected to create a new ARC/INFO coverage, which was subsequently used as a basemap for all the maps in UNEP's World Atlas of Desertification (see reference below).

The global boundaries template contains 306 polygons of four types, which are coded in the data set as follows: 1) Oceans; 2) Lakes; 3) Continents; and 4) Islands. It is available from GRID as a single ARC/INFO 'EXPORT'-format file comprising 1.7 Mb when uncompressed. While the original projection ISRIC used for the GLASOD wall map was the Mercator to display the various continents with as little distortion as possible, it is distributed by GRID in either the Van der Grinten (a variation of Mercator) or the Geographic projection.

The sources of the global boundaries template are ISRIC and UNEP/GRID, and the proper references are as follows:

Oldeman, L. R., Hakkeling, R. T. A. and W. G. Sombroek. October 1990. "World Map of the Status of Human-Induced Soil Degradation; Explanatory Note". (The) Global Assessment of Soil Degradation, ISRIC and UNEP in cooperation with the Winand Staring Centre, ISSS, FAO and ITC; 27 pages.

Deichmann, Uwe and Lars Eklundh. July 1991. "Global digital data sets for land degradation studies: a GIS approach". GRID Case Study Series No. 4; UNEP/GEMS & GRID; Nairobi, Kenya; 103 pages (mostly pp. 29-32). An additional reference is UNEP's 1992 World Atlas of Desertification (Edward Arnold, London, UK, 69 pages - see pages vii to ix).