Water Erosion Prediction Using the Revised Universal Soil Loss Equation (RUSLE) in a GIS Framework, Central Chile

Carlos A. Bonilla1*, José L. Reyes1, and Antoni Magri2

Soil erosion is a growing problem in Central Chile, particularly in coastal dry lands, where it can significantly decrease the productivity of rainfed agriculture and forestry. In this study, the Revised Universal Soil Loss Equation (RUSLE) was integrated into a Geographic Information System (GIS), and used to evaluate the effects of different combinations of vegetative cover on soil erosion rates for Santo Domingo County in Central Chile. Implementing RUSLE in the GIS required a complete description of the county’s soils, climate, topography and current land use/land cover. This information was compiled in rasters of 25 x 25 m cells. RUSLE parameter values were assigned to each cell and annual soil loss estimates were generated on a cell by cell basis. Soil losses were estimated for the current and for three alternate scenarios of vegetative cover. Under current conditions, 39.7% of the county is predicted to have low erosion rates (< 0.1 t ha-1 yr-1), 39.8% has intermediate rates (0.1-1.0 t ha-1 yr-1), and 10.4% has high erosion rates (> 1.1 t ha-1 yr-1). The remainder of the surface (10.2%) is not subject to erosion. Under the recommended alternate scenario, 89.3% of the county is predicted to have low erosion rates, and no areas are affected by high soil loss, reducing soil erosion to a level that will not affect long term productivity. This paper describes how RUSLE was implemented in the GIS, and the methodology and equations used to evaluate the effects of the land use/land cover changes.

Keywords: RUSLE, water erosion, soil conservation, forestry, changes in land use/land cover, Central Chile.
1Pontificia Universidad Católica de Chile, Escuela de Ingeniería, Vicuña Mackenna 4860, Santiago, Chile. *Corresponding author (cbonilla@ing.puc.cl).
2Magri Consultores Ltda., Don Carlos 2939, Oficina 613, Santiago, Chile.