Spatiotemporal classification of drought severity

The growing number and effectiveness of earth observation satellite systems, along with the increasing reliability of remote sensing methodologies and techniques, present a wide range of new capabilities in monitoring and assessing droughts. In this paper, several drought features are analyzed and assessed by using remotely sensed Reconnaissance Drought Index (RDI). The developed methodology is applied to the region of Thessaly in Central Greece, which is the major agricultural area in the country. In particular, severity, areal extent, duration, onset and end time are analyzed from monthly RDI images over the period 1981-2001. The results show an increase in the areal extent of drought during each episode and that droughts are classified in two classes, namely mild to moderate and severe to extreme, respectively, lasting about one hydrological year. The onset of severe to extreme droughts coincides with the beginning of the hydrological year, whereas the onset of mild to moderate droughts is in spring