Distribución temporal de la erosividad de la lluvia en Tacuarembó y Rivera

The Universal Soil Loss Equation (USLE) (Wischmeier & Smith, 1965, 1978) and its revised version RUSLE (Renard et al., 1997) are the models used in the implementation of the current public soil conservation policies in Uruguay. Its rainfall and associated runoff erosivity factor (R) is the average annual value of the EI₃₀ index of all erosive rainfall events that occur in a year for a long series of years. The calculation for a specific location requires pluviographic information of at least 20 years, as updated as possible and with high temporal resolution (<30 minutes) (Panagos et al., 2017). This type of information is usually not available or has limited temporal scope (Klik et al., 2015). To overcome this limitation, 14 years of rainfall records (2000-2014) from a weather station located at "La Corona" Farm, Tacuarembó department were analyzed. Regressions were developed which allowed relating the EI₃₀ index derived in this site with the long-term daily rainfall information (1979-2009) available in the locations of Tacuarembó and Rivera, distant 29 and 80 km from La Corona Farm, respectively. These regressions presented adjusted R² determination coefficients between 0.66 and 0.82. The current recommendations of RUSLE 2 were incorporated into the EI₃₀ index estimates regarding the calculation of the kinetic energy of erosive storms. The estimated R factors for the period 1979-2009 in Tacuarembó and Rivera are 7949 and 8632 MJ mm ha^-1 h^-1 year^-1, respectively. Both values indicate a high erosive potential of the rainfall events. Their return periods are 2.6 and 1.95 years, with probabilities of occurrence of 38.6 and 51.3%, respectively. Summer and autumn concentrate approximately 65% of the average annual erosivity. The estimated R factor values agree with those reported in the bibliography for the area. The methodology used in this work can offer a useful alternative in the estimation of the R factor, as well as its seasonal and monthly distribution, in nearby locations where pluviographic information is not accessible, but long-term rainfall records are available.