Forests play an important role in reducing erosion. In Vietnam, destroying natural forests in mountainous areas has caused serious environmental problems for sustainable development. Required forest areas for protection of soils from erosion in Vietnam are defined in this study. An algorithm of defining required forest area for soil erosion prevention is based on a comparison of soil loss prediction and its threshold of 10 ton ha-1yr-1 (soil loss tolerance) within the GIS environment. Soil loss is predicted from rainfall erosivity index, slope, porosity and.
