ABSTRACT
Drought Indices (DI) are quantitative measures useful for monitoring droughts and assessing their effects (Mishra & Singh, 2010; Nuñez et al. 2014; Zargar et al. 2011). Among the indices more widely used in drought science and planning stand out those belonging to the family of standardized indices (SDI). The Standardized Precipitation Index (SPI) (Guttman, 1999) is by far the most adopted one and its use is recommended by the World Meteorological Organization as “the standard index” for monitoring meteorological droughts (Hayes et al. 2011). Other SDIs as the Standardized Precipitation Evapotranspiration Index (SPEI) (Vicente-Serrano et al. 2010) have been proposed as a more accurate measurement of the soil water balance and dynamics, especially in climate regimes, as the Mediterranean, in which rainfall and potential evapotranspiration dynamics are out of phase.
