GMIA shows the amount of area equipped for irrigation around the year 2005 in percentage of the total area on a raster with a spatial resolution of 5 arc-minutes (about 10 km at the equator). Additional map layers show the percentage of the area equipped for irrigation that was actually used for irrigation and the percentages of the area equipped for irrigation that was irrigated with groundwater, surface water or non-conventional sources of water. The data layer on area equipped for irrigation was developed by combining sub-national irrigation statistics with geospatial information on the position and extent of irrigation schemes to compute the irrigation density (fraction of 5 arc-minute cells equipped for irrigation). The information for the additional layers on area actually irrigated or on the water source for irrigation was derived from statistical survey data (e.g. census reports) only, therefore the accuracy at pixel level is limited. GIS users can import the map as either ASCII grids or as shape files.
