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- Title
Exploring the effect of different time resolutions to calculate the rainfall erosivity factor R in Calabria, southern Italy.
- Authors
Porto, Paolo
- Abstract
The rainfall erosivity factor R of the Universal Soil Loss Equation is a good indicator of the potential of a storm to erode soil, as it quantifies the raindrop impact effect on the soil based on storm intensity. The R-factor is defined as the average annual value of rainfall erosion index, EI, calculated by cumulating the EI values obtained for individual storms for at least 22 years. By definition, calculation of EI is based on rainfall measurements at short time intervals over which the intensity is essentially constant, i.e. using so-called breakpoint data. Because of the scarcity of breakpoint rainfall data, many authors have used different time resolutions (Δ t = 5, 10, 15, 30, and 60 min) to deduce EI in different areas of the world. This procedure affects the real value of EI because it is strongly dependent on Δ t. In this contribution, after a general overview of similar studies carried out in different countries, the relationship between EI and Δ t is explored in Calabria, southern Italy. The use of 17 139 storm events collected from 65 rainfall stations allowed the calculation of EI for different time intervals ranging from 5 to 60 min. The overall results confirm that calculation of EI is dependent on time resolution and a conversion factor able to provide its value for the required Δ t is necessary. Based on these results, a parametric equation that gives EI as a function of Δ t is proposed, and a regional map of the scale parameter a that represents the conversion factor for converting fixed-interval values of ( EI30)Δ t to values of ( EI30)15 is provided in order to calculate R anywhere in the region using rainfall data of 60 min. Copyright © 2015 John Wiley & Sons, Ltd.
- Subjects
CALABRIA (Italy); RAINFALL; SOIL erosion prediction; STORMS; SOIL dynamics; PARAMETRIC equations
- Publication
Hydrological Processes, 2016, Vol 30, Issue 10, p1551
- ISSN
0885-6087
- Publication type
Article
- DOI
10.1002/hyp.10737