Prescreening of Sedimentation Potential in Harbor Approach Channels: A Parametric Model

Abstract

<pre style="color: rgb(0, 0, 0); text-wrap-mode: wrap;">In this study, a parametric model was developed to prescreen the sedimentation potential and maintenance dredging frequency for harbor approach channels under the action of combined current and nonbreaking waves. The model is fast, easy to implement, and well-suited for preliminary assessment for a given set of ship, metocean, and sediment characteristics. To resolve the velocity profile, a refined wave-altered current profile was implemented in the model in favor of a simple power-law current profile, which improved the model performance substantially. The model was first validated against the results reported in an experimental study, and then verified against field measurements of the Damietta Harbor approach channel. Finally, a parametric study was conducted to investigate the influences of (1) median grain size of seabed sediment, (2) wave severity, and (3) depth-averaged current velocity on the sedimentation in approach channels. The results showed that the dredging frequency of approach channels is mainly governed by the wave characteristics, i.e., wave severity, in the case of combined waves and current. It was further shown that representing the wave-altered current profile in simplified models is particularly important. Otherwise, the model would yield unrealistically high dredging frequencies when the current velocity approaches zero, even under severe waves.AB - In this study, a parametric model was developed to prescreen the sedimentation potential and maintenance dredging frequency for harbor approach channels under the action of combined current and nonbreaking waves. The model is fast, easy to implement, and well-suited for preliminary assessment for a given set of ship, metocean, and sediment characteristics. To resolve the velocity profile, a refined wave-altered current profile was implemented in the model in favor of a simple power-law current profile, which improved the model performance substantially. The model was first validated against the results reported in an experimental study, and then verified against field measurements of the Damietta Harbor approach channel. Finally, a parametric study was conducted to investigate the influences of (1) median grain size of seabed sediment, (2) wave severity, and (3) depth-averaged current velocity on the sedimentation in approach channels. The results showed that the dredging frequency of approach channels is mainly governed by the wave characteristics, i.e., wave severity, in the case of combined waves and current. It was further shown that representing the wave-altered current profile in simplified models is particularly important. Otherwise, the model would yield unrealistically high dredging frequencies when the current velocity approaches zero, even under severe waves.</pre>