Abstract
ABSTRACTSoil erosion by water is a serious threat for the Mediterranean region. Raindrop impacts and consequent runoff generation are the main driving forces of this geomorphic process of soil degradation. The potential ability for rainfall to cause soil loss is expressed as rainfall erosivity, a key parameter required by most soil loss prediction models. In Italy, rainfall erosivity measurements are limited to few locations, preventing researchers from effectively assessing the geography and magnitude of soil loss across the country. The objectives of this study were to investigate the spatio-temporal distribution of rainfall erosivity in Italy and to develop a national-scale grid-based map of rainfall erosivity. Thus, annual rainfall erosivity values were measured and subsequently interpolated using a geostatistical approach. Time series of pluviographic records (10-years) with high temporal resolution (mostly 30-min) for 386 meteorological stations were analysed. Regression-kriging was used to interpolate rainfall erosivity values of the meteorological stations to an Italian rainfall erosivity map (500-m). A set of 23 environmental covariates was tested, of which seven covariates were selected based on a stepwise approach (mostly significant at the 0.01 level). The interpolation method showed a good performance for both the cross-validation data set ( = 0.777) and the fitting data set (R2 = 0.779).
Highlights
Soil erosion by water is the ongoing geomorphic process of soil degradation studied most in the Mediterranean region (Kosmas et al 1997; Boardman and Poesen 2006)
The comprehensive rainfall-runoff erosivity factor R, proposed in the Universal Soil Loss Equation (USLE) and RUSLE soil erosion prediction models (Wischmeier and Smith 1978; Renard et al 1997), is recognized as one of the best indicators to measure the erosive potential of a rainstorm (Renard et al 1991)
The average annual R-factor of the investigated meteorological stations totals 1715.2 MJ mm h−1 ha−1 yr−1, with a standard deviation of 1171.2 MJ mm h−1 ha−1 yr−1. This value is more than two times higher than the average R-value obtained by the 1290 non-Italian stations (723 MJ mm h−1 ha−1 yr−1) contained in the Rainfall Erosivity Database on the European Scale (REDES) (Panagos et al 2015)
Summary
Soil erosion by water is the ongoing geomorphic process of soil degradation studied most in the Mediterranean region (Kosmas et al 1997; Boardman and Poesen 2006). It is a widespread phenomenon (Cerdan et al 2010) that affects several Mediterranean landscapes (Panagos et al 2015) causing on-site and off-site environmental impacts (Rodolfi 2006; Morgan 2009). The comprehensive rainfall-runoff erosivity factor R, proposed in the USLE and RUSLE soil erosion prediction models (Wischmeier and Smith 1978; Renard et al 1997), is recognized as one of the best indicators to measure the erosive potential of a rainstorm (Renard et al 1991). The R-factor is found to be a suitable
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