During numeric modeling of clastic sedimentation, the modeler is faced with assigning values to several parameters that are difficult to estimate. However, proper handling of uncertainties translates to valuable uncertainty information in the output. To illustrate this process, we used a model called GPM (Geologic Process Modeler) to reproduce a deepwater turbidite system from the Campos Basin, offshore Brazil, for which good-quality 3D seismic was available. In the first stage we used a paleo-basin floor surface reconstructed from seismic and placed sediment sources at locations indicated by the inferred paleogeography. In the second stage, we varied several input parameters within a range of reasonable values while comparing results to observed data. The results of all plausible models, considered jointly, provide a picture of the uncertainty of the occurrence of observed features and sediment properties.