EVALUATION AND PREDICTION OF WATER EROSION IN ARID STEEPLY SLOPED AREAS IN THE CENTRALWESTERN PART OF ARGENTINA
Authors: Alberto I. J. Vich, Adriana Mariani and Armando Pedrani
Abstract: Water erosion, especially in wild areas, is a complex phenomenon whose magnitude has not been properly acknowledged in Argentina. There are practically no systematic quantitative observations, with the exception of those shown here. Measurements were carried out west of the city of Mendoza (Argentina), at 32° 52' 50" south latitude and 68° 52' 00" west longitude. They were conducted in areas with poorly developed soils with mild arid climate. Measurements of soil losses (PS) were performed during the 1982-95 period on plots with bare soil and varied exposure and slope. Application and adjustment of the USLE as a prediction tool was examined and its components were assessed. It is used to predict soil losses caused by individual events since erosive storms are not frequent. Given the fact that the rainfall erodibility factor does not adequately explain soil loss variations, different forms were proposed that combined rainfall intensity and runoff. The remaining factors were assessed with the original methodology, and the protective effect of rock fragments found in the soil profile and surface was included in the coverage factor. Adjustment of the original equation and proposals was carried out through optimization with individual data. Applicability of the USLE or modified expressions for predicting erodibility from individual events has not proved to be satisfactory due to the random nature of predictions. It is, therefore, essential to collect more information.