Evaluación de modelos para estimar la erosividad de la lluvia en el Valle del Cauca, Colombia

Rainfall erosivity (R) is one of the factors included in the Universal Soil Loss Equation (USLE) and it is defined as the potential capacity of the rain to erode soils, which knowledge is essential in planning the use and handling them. In the work, two methods (USLE-EI30 and EI30cor) were evaluated to determine the R factor in the main pineapple producing municipalities of Valle del Cauca, in addition, the Fournier (IF) and Modified Fournier (IMF) indices were analyzed; for this, the precipitation records of 12 pluviographic, pluviometric, and climatological stations belonging to the study area were used, during the years 2015-2019, taking into account the availability of the data. It was found that 66 % of the annual rainfall and 69 % of the erosive events occur in the months of March to May and September to November, responding to the bimodal regime. Regarding the USLE-EI30, values between 636.7 and 4384.0 MJ.mm.ha-1 were found, while with the EI30cor the values ranged between 2850.5 and 11110.7 MJ.mm.ha-1. The analysis of the linear regression between the erosivity indices and the mean annual precipitation showed a higher R2 for the case of the IMF (0.976). Finally, the USLE-EI30 was significantly correlated with the annual IMF (R2 = 0.89), generating the adjusted model (EI30 = 20.979 (IFM)-389.04; r = 0.95); furthermore, it was evidenced that more than 70 % of the study area presents very low erosivity (1000-2500 MJ.mm.ha-1).