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A Numerical Sediment Transport Model for Application to Natural Estuaries, Harbours and Rivers

1987; Elsevier BV; Linguagem: Inglês

10.1016/s0304-0208(08)70030-6

2212-1048

Kerry Black,

Geological formations and processes

2SS is a pseudo-three-dimensional numerical, sediment transport model of bedload and suspended sediment movement. Under current flow simulated with a two-dimensional hydrodynamic model, 2SS models sediment dynamics, finding sediment fluxes and corresponding erosion and deposition rates. Designed for general application to an estuary, harbour or river, the model contains a comprehensive numerical specification of these environments, emulating characteristic natural phenomena identified during field investigations. The varying composition of sea floor of sand, shell lag, rock etc. found to commonly occur in natural estuaries is described numerically in the model, according to the local availability of transportable material. To control sediment transmission across all bed types, a two-stage advection scheme was designed for the non-conservative suspended sediment transmitted on a grid of point sources or sinks. To adequately simulate the ebb- and flood-tidal deltas of natural estuaries, a formula for sub-threshold flow was developed to predict the slow deposition rate (retarded by residual flow turbulence) of sediment left suspended after a spatial or temporal deceleration. Above threshold, sediment entering a spatial deceleration is also given time to deposit by enabling currents to carry higher loads than the local current strengths would normally allow. These emulations are verified using field measurements which were required for the support and calibration of 2SS during two large-scale estuarine investigations for planned port and harbour works. The model was applied to assess the effect on the marine environment of these works and to predict maintenance dredging for developments such as shipping channel, quay wall and causeway constructions, as well as permitting an examination of the causes and future direction of natural bathymetric changes.