Changes in rainfall erosivity are an expected consequence of climate change. Long-term series of the single storm erosionindex, EI, may be analysed to detect trends in rainfall erosivity. An indirect approach has to be applied for estimating EI, giventhat long series of rainfall intensities are seldom available. In this paper, a method for estimating EI from the correspondingrainfall amount, he, was developed for Sicily. This method was then applied at 17 Sicilian locations, representative of differentclimatic zones of the region, to generate a long series (i.e. from 1916 to 1999 in most cases) of EI values. Linear and step(step located at 1970) trends in annual and seasonal erosivity were detected by both classical approaches (Mann–Kendall test,Wilcoxon-Mann-Whitney rank-sum test) and a new empirical approach (quantile approach, QA), based on the determinationof the erosivity values corresponding to selected probability levels. A power relationship between EI and he with a spaceandtime-variable scale factor and a time-variable process parameter yielded the most accurate predictions of EI. However, asimpler model, using a time-variable scale factor and a constant process parameter, yielded reasonably accurate EI estimates.Annual erosivity did not increase in Sicily during the twentieth century. At the most, it decreased at a few locations (threeof the 17 considered locations). Significant trends were observed more frequently for winter erosivity (six locations) thanfor summer erosivity (two locations), suggesting that the erosive storms of winter determined the occasional occurrence ofa negative trend in annual erosivity. In general, the QA compared reasonably well with more classical approaches. The QAappears promising since step trends for different return periods may be detected but efforts are needed to statistically formalizethe proposed approach.
|Stato di pubblicazione||Published - 2007|
All Science Journal Classification (ASJC) codes
- Water Science and Technology