This indicator measures the total dryland area (in sq. km) that can be defined as semiarid, in a given country.
Aridity zones were derived from an Aridity Index (AI) which is calculated as the ratio of precipitation to potential evapotranspiration (P/PET). Semiarid areas fall into the 0.20 - 0.50 P/PET interval.
The values of this indicator have been aggregated at the country level by ILRI, in collaboration with the ILC's Rangelands initiative, based on:
- UNEP-WCMC (2007): A spatial analysis approach to the global delineation of dryland areas of relevance to the CBD Programme of Work on Dry and Subhumid Lands.
- Dataset based on spatial analysis between WWF terrestrial ecoregions (WWF-US, 2004) and aridity zones (CRU/UEA; UNEPGRID, 1991). Dataset checked and refined to remove many gaps, overlaps and slivers (July 2014).