Assessment of Drought Indexes on Different Time Scales: A Case in Semiarid Mediterranean Grasslands

Drought is a significant challenge to semiarid Mediterranean grasslands, Increasing the accuracy of monitoring allows improving conservation and management these vital ecosystems. Meteorological drought commonly monitored by Standard Precipitation Index (SPI) or Evapotranspiration (SPEI). On other hand, agriculture estimated Vegetation Health (VHI). This work aims optimise correlation between both types using best transformation VHI most appropriate time scale. Two drought-vulnerable grasslands were selected evaluate performance indexes. The SPI SPEI calculated data obtained from nearby weather stations. MODIS used calculate VHI. index was standardised, naming it as SVHI. Our results revealed that better correlated with compared SPI. In addition, SVHI in critical vegetation phases than Overall, quarterly scale showed stronger relationships monthly frame spring autumn. fact suggests could provide plus point for increasing precision during periods.