Detecting trends of extreme rainfall series in Sicily

Abstract

Abstract. The objective of the study is to assess the presence of linear and non linear trends in annual maximum rainfall series of different durations observed in Sicily. In particular, annual maximum rainfall series with at least 50 years of records starting from the 1920's are selected, and for each duration (1, 3, 6, 12 and 24 h) the Student's t test and the MannKendall test, respectively, for linear and non linear trend detection, are applied also by means of bootstrap techniques. The effect of trend on the assessment of the return period of a critical event is also analysed. In particular, return periods related to a storm, recently occurred along the East Coast of Sicily, are computed by estimating parameters based on several sub-series extracted from the whole observation period. Such return period estimates are also compared with confidence intervals computed by bootstrap. Results indicate that for shorter durations, the investigated series generally exhibit increasing trends while as longer durations are considered, more and more series exhibit decreasing trends.

A comprehensive analysis of changes in precipitation regime in Tuscany

“…The results obtained with the three methods of fitting for the extreme value analysis, Gumbel moments, GEV moments, and GEV-L moments are almost the same, confirming the findings of Bonaccorso et al (2005). The choice of the RP was also not critical, as the analysis was focused on change detection rather than on value estimation.…”

“…A comparison of nine global GCMs shows a tendency towards an increase in 1884 SIMONE FATICHI AND ENRICA CAPORALI extreme events (Tebaldi et al, 2006). Scientific observations also indicate that an increase in extreme rainfall events is observable in many areas all around the world, including northern and southern Italy (Hopkins and Holland, 1997;De Michele et al, 1998;Mason et al, 1999;Brunetti et al, 2000;Fowler and Kilsby, 2003;Groisman et al, 2004;Bonaccorso et al, 2005). Even in Tuscany, a region located in central Italy, some authors have identified signals of climate change by analyzing extreme rainfall and hailstorms (Crisci et al, 2002;Piani et al, 2005).…”

“…Even if the choice of the distribution is not critical, as the study is not aimed at accurately evaluating the precipitation value for a certain return period (RP), but rather at estimating if this value is going to change (Bonaccorso et al, 2005), the authors analysed the time series with three different approaches. In the first, the Gumbel distribution was used and the associated parameters were determined with the method of moments.…”

Extreme Rainfall Nonstationarity Investigation and Intensity–Frequency–Duration Relationship

“…Therefore, it is essential to conduct extreme rainfall trend analysis at finer temporal scales, since urban flash flooding is the product of heavy rainfalls over short durations. Studies addressing non-4 stationarity in extreme rainfall events are very rare in the literature for sub-daily temporal scales (Bonaccorso et al 2005, Rosenberg et al 2010, Jacob et al 2011.…”

“…However, extreme rainfall trends can show large variations over short durations (Bonaccorso et al 2005). Therefore, it is essential to conduct extreme rainfall trend analysis at finer temporal scales, since urban flash flooding is the product of heavy rainfalls over short durations.…”