Short‐Duration Rainfalls in Sicily

The Italian Hydrographic Service publishes yearly maximum rainfall depths with 1-, 3-, 6-, 12-, and 24-hr duration, recorded by recording rain gauges. It also publishes selected short-duration ($t<1$ hr) rainfall amounts. It is impossible to carry out a statistical analysis of the short-duration rainfalls for each recording rain gauge because the published data correspond to different record durations and to different recording rain gauges from year to year. Therefore, there is a practical need to derive empirical relationships between the 1-, 3-, 6-, 12-, and 24-hr duration amounts and shorter duration ($t<1$ hr) rainfall amounts. Such a relationship has been proposed by Bell and has been verified using rainfall data in the United States, South Africa, and Australia. In this technical note we study the applicability of Bell's rainfall-duration relationship in Sicily and Sardinia. Then, using mean values of the ratio between the depth of rainfall occurring in t min and that occurring in 60 min, we obtain, for each island, an exponential relationship between this ratio and duration t. The two exponential relationships give values quasi-equal to those calculated by Bell's relationship. This result seems to confirm the independence of short-duration rainfalls of geographical factors.