Modelling processes influencing shelf edge exchange of water and suspended sediment

Abstract

The major processes, and the associated models, which describe shelf edge exchange, and across-shelf movement of suspended sediment are briefly reviewed, and illustrated using results from numerical models and references to the literature. The across-shelf exchange of sediment due to internal tide, along-shelf flow, wind and wind wave effects (primarily swell) is examined. Calculations show the importance of the internal tide in suspending sediment at the shelf edge with wind waves influencing the nearshore suspension, and wind driven flows leading to sediment advection. Barotropic and baroclinic processes in shelf edge regions lead to significant meanders and eddy generation, and associated exchange. This is briefly discussed with reference to the recent literature, and illustrated in terms of barotropic instability. The role of eddies in transporting suspended sediment is briefly discussed and illustrated in the case of an isolated eddy. Ocean–shelf water exchange due to dense overflows (cascading) is described, and the role of entrainment and small-scale topography upon this process is illustrated in a number of calculations. The influence of large-scale topography, namely submarine canyons upon the movement of dense water bottom plumes into the ocean and the resulting eddies is briefly discussed and illustrated with reference to the recent literature. Future modelling involving shelf–ocean models with irregular grids and non-hydrostatic capabilities is suggested as an important development topic.