An erosion and sedimentation model, erosion and sedimentation estimation tool (EROSET), was developed and applied to a watershed in Happy Valley, South Australia. The model simulates the dynamics of event runoff, soil detachment, and transport processes. The erosion and sedimentation model is able to predict watershed erosion and deposition for storm events at an element as well as watershed scale. The model was developed and incorporated into an existing rainfall-runoff model based on a contour-based digital elevation framework. It combines the use of the USLE data source and extended erosion and transportation modeling into a distributed and intra storm erosion and deposition analysis. This results in storm-based, time-variant, distributed erosion and deposition modeling in the watershed for both storm-based and long-term sediment estimation. The modeling can better enable land managers to identify the areas in a watershed where erosion and deposition may occur. The modeled processes and results can be related to total storm erosion estimated by MUSLE, although they operate on different temporal and spatial frames. Satisfactory modeling results were obtained with very limited calibration which compares well with other studies.