Climate quality index: Climatic aspects has been analyzed through the Aridity index (AI), using the methodology developed by FMA in accordance with the following formula

AI = P / PET where AI = Aridity index P = Yearly mean rainfall PET = Yearly mean potential evapotranspiration

Soil quality index: The soil quality index (SQI), developed by Sahara and Sahel Observatory (OSS), is based on four parameters:

• Parental material
• Soil depth
• Texture
• Slope

SQI is given by the geometric average of the indices for the four parameters:

SQI: = (Parental material * soil depth * texture * slope) raised to the 0,25 power

In case local data are not available for a single parameter, only the remaining parameters were used.

Vegetation quality index: Each CLC clas was assigned a value for each of these four parameters: erosion protection, resistance to drought, ground coverage. The same range of values was used for all four parameters: 0 (excluded from futher consideration), 1 (good), 1.5 (moderate), 2 (bad).

VQI is given by the geometric average of the indexes for the four parameters:

VQI = (ResistFire * ErosionProtection * ResistDrought * Coverage) raised to the 0,25 power

See, also: http://dismed.eionet.eu.int/Facilities/dismed_products/VQI

Climate quality index: Coast Layer: - ESRI Digital Chart of the World 1:1M Digital Elevation Model: - USGS/EDC GTOPO 30 Rainfall data: - FAOCLIM 2 database (version 2.01) Temperature data: - FAOCLIM 2 database (version 2.01) Penman values: - FAOCLIM 2 database (version 2.01) - Portuguese Meteorological Institute (for Portugal only)

Soil quality index: European Soil Database (ESDB) version 1 from Joint Research Center

Vegetation quality index: Corine land cover 1990 from European Environment Agency