Rainfall and drought in southern Italy (1821-2001)

Southern Italian monthly rainfall and temperature data for the period 1821--2001 were analysed statistically. The data were selected for 126 rain- gauges with the most complete time series. The main study period for which reliable and gap-free annual data are available was 1921--2001. During this period a widespread decreasing trend in annual rainfall was observed for over 96% of the area. This trend was most severe where mean annual rainfall was highest. A decreasing trend of less than 9 mm year was found in the worst case. Analysis of the historical series showed that this trend became more apparent after 1980, the period subjected to two serious droughts (1988--1992 and 2000--2001). In particular, a significant deficit in winter rainfall was found after 1980. Monthly temperatures were also considered. Net rainfall was calculated as a function of monthly rainfall and temperature. Negative trends and the effects of recent droughts were enhanced in terms of net rainfall.