Drought assessment in the Sardinia region (Italy) during 1922-2011 using the Standardized Precipitation Index

In this paper, the Standardized Precipitation Index (SPI), at both short-time and long-time scale, has been evaluated to analyse drought in the Sardinia region (Italy). In fact, while the short-time scale SPI describes droughts that affect plant life and farming, the long-time scale SPI influences the way water supplies/reserves are managed. Initially, with the aim to detect the most important drought episodes which affected the region, for each month, the percentage of rain gauges showing severe or extreme drought values has been evaluated. Then, in order to evaluate the temporal evolution of the SPI values, a trend analysis has been performed. Results evidenced that, at the short-time scale, the observation period has been characterized by several dry episodes while, at the long-time scale, the majority of the drought events have been detected after 1980. Moreover, marked negative trends of the SPI values in winter, in the wet season and at annual scale have been detected.