Distributed sediment yield modelling: Importance of initial sediment conditions

• Three models were calibrated using three different initial deposit estimation strategies.
• A sedigraphs analysis showed that all strategies provided adequate results.
• A rating curve analysis proved that the choice of initial conditions affected simulation results.
• Manual calibration of initial deposits showed best results in term of clockwise loop reproduction.
• Warm-up simulation strategy showed the best results in terms of reproducing different loop shapes.

The importance of initial sediment conditions on model calibration and validation is analysed. A sediment model was calibrated and validated under three different initial sediment conditions: (0) no sediment availability, (1) calibration of the initial sediment condition and (2) using a warm-up simulation. The model results were assessed in terms of the graphic of fine sediment transport, or sedigraphs, and the visual fit of the hysteresis on the sediment rating.All strategies provided adequate results. However, the loop rating curve analysis demonstrated that the choice of initial sediment conditions affected the simulation results. Without any initial sediment condition, the model results were typically inferior to the simulation results with calibration or warm-up. The calibration of initial conditions proved to be the most reliable technique to generate clockwise hysteresis loops, but failed in reproducing other loop types. Overall, the warm-up simulations showed encouraging results, providing satisfactory fine sedigraph simulation results.