The 18O content of rain and river waters was used as an isotopic tracer in order to carry out the hydrograph separation of the Amazon river, during the 1973-1974 hydrological years, and to estimate the contributions of the surface runoff (event water) and baseflow (pre-event water) components to the total river flow. The average surface runoff and baseflow contributions were 30.3 and 69.7% respectively. At peak discharge, the mean contribution of the baseflow was about 57%. The results of the isotopic separation model were compared with the filter-separation autoregressive method, showing similar behavior and magnitude.
isotopic tracers; hydrograph separation; Amazon river
