The Generic IWMI 951 Class map (Generic-IWMI-951) is the base product from which the Global irrigated area map (GIAM), the Global Map of Rainfed Cropland Areas (GMRCA), and Global Map of Land Use/Land Cover Areas (GMLULCA) were derived. The methodology on how the 951 class map was produced has been presented in the detailed documentation presented in this paper. First, the irrigated area classes, the rainfed area classes, and the other land use/land cover (LULC) classes were identified and labeled based on an elaborate set of methods and techniques (see documentation) for each of the seven segments of the World. The seven segments were: 

1.             Precipitation less than 360 mm per year segment (PLT360-segment);

2.             Precipitation greater than 2400 mm per year segment (PGT2400-segment);

3.             Temperature less than 280 degree Kelvin segment (TLT280-segment);

4.             Forest cover greater than 75 mm segment (FGT75-segment);

5.             Elevation greater than 1500 mm segment (EGT1500-segment);

6.             All other areas of the World segment (AOAW-segment); and

7.             Rainforest synthetic aperture radar segment (RFSAR-segment).

The segments were masked and analyzed using the time-series mega-file data from SPOT 1-km, AVHRR 10-km, and secondary datasets such as 1-kmGTOPO30 elevation, 1-km forest cover, 40-yr monthly rainfall, and 10-km AVHRR skin temperature. The classes identified from each of the segments were mosaicked into a single file that added up to 951 classes and is called Generic IWMI 951 Class Map (Generic-IWMI-951). The 951 classes were refined into various aggregated and disaggregated maps specifically for GIAM, GMRCA, and GMLULCA.

The Generic 951 class map and image are specifically useful for those interested in producing their own refined map. For example, a more detailed irrigated area map or rainfed cropland map, or a LULC map of specific Countries or regions will be of value when the can better combine and/or label classes based on local knowledge. It must be noted that the class labels in the 951 class map/image are indicative rather than definitive. So a user can always label a class better. The characteristics include, for each of the 951 classes: (a) month-by-month 10-km AVHRR spectral band reflectivity for band 1 (red) and band 2 (near-infrared), (b) month-by-month 10-km AVHRR brightness temperature for thermal bands 4 and 5; (c) month-by-month 10-km AVHRR NDVI, (d) month-by-month 1-km SPOT vegetation NDVI, (e) elevation (meters), (f) skin temperature (degree kelvin), (g) mean rainfall (mm/month), and (h) tree cover (percent).