It was carried out the characterization of the mechanical and chemical erosive processes in the Piracicaba River basin, for the period 1992-1996, in terms of the fluvial transport of dissolved and particulate materials. The mechanical erosion was calculated from the suspended sediment transport in the basin, considering the surface runoff discharge and the respective concentration calculated taking in account the statistical hydrogram separation method employed. The specific physical degradation calculated for the Piracicaba River basin was 90 t/km2.a, which correspond the velocity of the soil thickness reduction of about 64 m/Ma. The dissolved load of Piracicaba River was corrected due to the influence of the atmospheric inputs, mainly for SO4 2-, Ca2+ and Mg2+ (79.6; 63.8 and 41.8%, respectively). After the input corrections, it was estimated the total atmospheric/soil CO2 consumed during the silicate weathering (229 x 103 moles/km2.a) and the total chemical erosion (16.6 t/km2.a) expressed in terms of the total dissolved solids transported in the basin. The velocity of the silicate rock profile reduction (2.8 m/Ma) was calculated by the fluvial transport of dissolved silica knowing the mean silica concentrations in the parent rock and in the soil profile
