Non-hydrostatic modeling of cohesive sediment transport associated with a subglacial buoyant jet in glacial fjords: A process-oriented approach

Fine sediment transport produced by a subglacial freshwater discharge is simulated with a 2D non-hydrostatic model. The circulation pattern revealed a buoyant jet issuing from the aperture representing the subglacial tunnel, a vertically buoyant plume and a surface gravity current forming part of an estuarine circulation. Momentum-dominated experiments are more sensitive to the presence of suspended sediment in the discharge. At low concentrations, the sediment stays in the vertical plume and surface gravity current, and its concentration is progressively decreased by mixing but no settling is observed through the water column. At high concentrations, the sediment settles in the far field and is transported back to the near field by the landward estuarine current. Sediment settled from the surface layer through convective sedimentation, a process that was more effective than flocculation to transport sediment vertically, and showed vertical velocities faster than 1.0×10-21.0×10-2 m s−1. Implications of these results are discussed.

► We modeled fine sediment transport in a glacial fjord with a 2D non-hydrostatic model. ► A detailed scheme of a jet, vertical plume and estuarine circulation was obtained. ► At high sediment concentrations, the density field is influenced by sediment. ► Fine sediment settles in the far field and then is transported back to the glacier. ► Convective sedimentation explains the rapid settling of sediment in the far field.