LAND-USE, HYDROLOGICAL PROPERTIES, AND SOIL ERODIBILITIES IN THE BIO-BIO RIVER BASIN, CENTRAL CHILE

The spatial variations of surface infiltration, subsoil permeability, and soil erodibility were studied in a mountain watershed located in the Cordillera de la Costa of the Bio-Bio River basin, Central Chile. The relationships between selected soil parameters and infiltration and permeability rates were established. Infiltration rates of the 0-10 cm surface soil varied from 280 to 0.9 mm h(-1) for native forest and degraded thicket, respectively. The organic matter content was the most important factor correlated with the infiltration rate. Other important parameters were bulk density and silt percentage. The permeability rates in areas of native forest and meadowland varied from 212 to 0.2 mm h(-1) respectively. Slope angle is the only site parameter that showed a significant relationship with the permeability sates. The watershed soils have a wide range of erodibility rates, with values from 0.073 t ha h ha(-1) MJ(-1) mm(-1) in degraded thicket lands, to 0.001 t ha h ha(-1) MJ(-1) mm(-1) in native forest lands where the soil profile has been kept intact.