SPATIOTEMPORAL VARIABILITY OF DROUGHT ON A SHORT-MEDIUM TIME SCALE IN THE CALABRIA REGION (SOUTHERN ITALY)

The study analyses spatial and temporal patterns of drought in an area with a wide range of precipitation characteristics (the Calabria region in southern Italy) during the period 1921-2007. The short-time (2, 3 and 6 months) SPI index was estimated to analyse drought especially from the agricultural point of view. Principal Component Analysis (PCA) was applied to the SPI to assess the spatial variability of drought. During the period of observation, moderate to severe drought occurred at a frequency of almost 13% in wet seasons (autumn and winter). Almost half of the region was affected by drought in the years 1981-1990 when the area experienced its most severe drought. Although the spatial patterns of drought estimated by PCA were logical and consistent with precipitation distribution, very complex patterns were observed for all the time scales looked at. The high fragmentation of the maps obtained makes them of limited value and caution is recommended in classifying the region into homogeneous areas.