Derived from the Global Agro-Ecological Zones Study, Food and Agriculture Organization of the United Nations (FAO), Land and Water Development Division (AGL) with the collaboration of the International Institute for Applied Systems Analysis (IIASA), 2000. Two sources of geo-referenced terrain slopes were available for use in the Global AEZ assessment: (i) terrain slopes indicated in the mapping unit expansion tables of the respective soil maps, and (ii) terrain slopes derived from GTOPO30 data (EROS Data Center, 1998). The latter terrain-slope database was established at IIASA using a rule-based algorithm to calculate slope distributions in terms of seven slope classes per 5 minute grid-cell of the DSMW soil data based on neighborhood relationships among grid-cells in the 30 arc-second GTOPO30 database. Slopes derived from the 30 arc-second DEM were allocated to soil units occurring within individual soil associations. This involved five steps: (i) Determination of slope classes for each 30 arc-second grid-cell of GTOPO30. Results are grouped in the following seven classes: 0-2%, 2-5%, 5-8%, 8-16%, 16-30%, 30-45% and > 45%; (ii) Aggregation of the results respectively to 5 minute latitude/longitude DSMW grid-cells, and to individual soil association map units resulting in a slope class distribution for each grid-cell and map unit; (iii) Defining priority classes of soil unit/slope relationships; (iv) Establishing for each soil association consistent rankings of slopes/soil units; (v) Allocation of individual soil units within a particular soil association map unit to 5 min grid-cells of the DSMW, according to calculated slope distributions.

WRIA_DEM: Hydrologically filled GTopo30 DEM with the main stems of cartographic rivers "burned-in" for irrigation analysis. GT30/GTopo30 is Global Topographic 30 arc second DEM database, nominal 1km postings; DEM is Digital Elevation Model. The WRIALAEA grid data layer is comprised of 9194x8736 derivative raster hydrologically filled dem features derived based on 1 kilometer data originally from FAO.

Digital Terrain Model within the Okavango Basin. Source: Data generated under the GIS EPSMO program (base:SRTM data). This dataset is part of the GIS Database for the Environment Protection and Sustainable Management of the Okavango River Basin project (EPSMO). Detailed information on the database can be found in the “GIS Database for the EPSMO Project” document produced by Luis Veríssimo (FAO consultant) in July 2009, and here available for download.

The Food and Agriculture Organization of the United Nations (FAO) with the collaboration of the International Institute for Applied Systems Analysis (IIASA), has developed a system that enables rational land-use planning on the basis of an inventory of land resources and evaluation of biophysical limitations and potentials. This is referred to as the Agro-ecological Zones (AEZ) methodology.

Soil and terrain suitability for maize dataset, at about 1 km resolution, investigates soil suitability and both soil and terrain suitability for maize, under rain-fed condition, with high and low inputs. The Soil and terrain suitability for crops datasets are part of the GAEZ v4 Theme 1 Land and Water Resources, Soil Suitability sub-theme. In the GAEZ v4 the Soil Suitability assessment sub-theme, soil qualities are evaluated for each crop and input/management level and for different water supply systems (rain-fed and irrigated). The results are crop and input level specific soil suitability ratings, which are used for the crop suitability and attainable yield assessment presented in Theme 4. Terrain suitability is also estimated according to terrain-slope classes and location-specific rainfall amounts and rainfall-concentration characteristics to account for soil erosion risks related to crop cover dynamics. Soil and terrain suitability are combined in an edaphic rating factor by crop, water supply type and input level, which is an important input for the estimation of agro-ecological crop suitability and attainable yields presented in Theme 4. For further details, please refer to the GAEZ v4 Model Documentation.