INFLO1 is an ANSI standard FORTRAN-77 predictive sedimentation model that simulates the behaviour of a hyperpycnal inflow. From data on discharge and sediment load at the river mouth as well as the basin geometry, INFLO1 predicts the flow parameters of the resulting turbidity current—flow thickness, velocity, volume and sediment discharge, and interstitial fluid density—and the deposition and erosion of sediment. Sensitivity analyses show that the simulated deposit morphology is most affected by changes in the drag coefficient and that the internal deposit architecture, parameterized by vertical variations in mean grain size, is most sensitive to the form of the flood hydrograph. Model predictions compare favourably with data derived from the 1663 Saguenay event. Given that hyperpycnal inflows are relatively frequent both on recent and geological timescales, INFLO1 allows for the reconstruction of flow parameters for past events yielding valuable paleoclimatic information and the assessment of the potential affects of future hyperpycnal inflows on sedimentation patterns and subaqueous structures.