The influence in rainfall erosivity calculation by using different temporal resolution in Mediterranean area

Rainfall erosivity (EI₃₀) is crucial to characterize the rainfall effect on soil erosion based on storm intensity. Its calculation is highly sensitive to the time resolution used, in which using rainfall data at fixed time intervals (ΔΤ) >30-min results in large underestimation. Therefore, there is a need to explore the difference and correlation between EI₃₀ calculated at different ΔΤ. One-minute rainfall data from 2006 to 2022 were collected from 6 stations over the Basilicata region in southern Italy to compute the maximum 30-min rainfall intensity (I₃₀), total kinetic energy of storm (KE), EI₃₀ and erosivity density values, for a total of 2516 storm events. These data constitute the actual values of I₃₀, KE and EI₃₀ and will be used as reference data. Underestimation of all the considered parameters were systematically evaluated using data aggregated at 5-, 10-, 15-, 30- and 60-min fixed interval. For ΔΤ ≤ 15 min the parameter responsible of the greatest underestimation turns out to be KE, whereas for coarser temporal resolution (ΔΤ > 30 min) I₃₀ plays a dominant role in underestimating EI₃₀. The use of coarse temporal resolutions also leads to >5 % loss of erosive events, especially those characterized by middle to high intensity/low duration (ΔΤ ≤ 45 min) events, as well as to an underestimation higher than 30 % in the estimated rainfall erosivity. The results show that an accurate estimation of the rainfall erosivity requires the use of rainfall data with a fixed time interval of length lower than 10 min.