Open-Water Disposal of Barged Sediments

A new model for assessing the behavior of sediment clouds due to open-water disposal from barges is presented. The model takes into account the realistic physical condition in which the disposed sediments, due to the large and finite amount of sediments typically carried by the barge, will initially descend as a sediment plume (as if from a continuous release) and then transit into a discrete sediment cloud (as if from an instantaneous release) after the barged sediments are fully discharged. These aspects are not represented in existing models so far. The model also includes the geometrical factors of the barge, which can significantly affect the source conditions and thus the subsequent descent process. Two types of predictions are provided by the model: (1) qualitative predictions of the flow regimes of the sediment clouds along the descending path in the water column, and (2) quantitative predictions of the gross characteristics, such as the penetration rate and growth size of the sediment clouds due to entrainment. An experimental study was also carried out for model verification. The comparison between experimental data and model predictions was satisfactory, whereas predictions with the existing models were found to be inadequate due to their oversimplified representations. Similar conclusions were also drawn in the comparison between available field data and model predictions.