Annual distribution of rainfall erosivity in the South-Central Region of Chile

Abstract

Among many factors involved in the water erosion process, precipitation is one of the most crucial when predicting the magnitude and occurrence of soil loss. Rainfall events, specifically their magnitude and intensity, contribute the energy necessary to remove and transport soil particles. In USLE, the erosive power of precipitation is accounted for in a rainfall-runoff erosivity factor (R), which combines the effects of the duration, magnitude and intensity of each rainfall event. In Chile, the absence of this type of information constitutes a serious limitation when evaluating soil loss, soil conservation, sustainability, and land-use plans. In this study, an analysis of the rainfall erosion index is performed for six locations in South-Central Chile (Caracol, Cerro El Padre, Chillán, Coihueco, Diguillín and Quilaco). EI30 and EI60 rainfall erosivity indices were calculated and correlated using data series with a high temporal resolution. The equation obtained was then applied to longer hourly precipitation data series, in order to calculate and fit the accumulated rainfall erosivity curves for different probabilities at each location. Also, equations for the rainfall erosivity based on daily, monthly and annual precipitation were obtained. Differences in the distribution of erosivity throughout the year were detected among locations. Ultimately, this work provides the values and seasonal variation of the rainfall erosion index in one of the areas that is most affected by water erosion in Chile.