Coastal Processes

Hydrodynamics

MetOcean Solutions Limited has modelled existing tidal, current, wave, and sediment transport dynamics, assessing the effects of dredging and disposal on the existing environment.

Their study has reviewed:

  • Changes to wave patterns, tides and currents, any resultant accretion or erosion of the sea floor from deepening the channel
  • Dispersal/settling of disturbed fine sediments, sediment plumes from dredging and disposal of dredge material.

Geomorphology

The Geomorphology study prepared by Tonkin and Taylor is informed by the hydrodynamic modelling. It has studied how the shoreline, seabed and tidal patterns will respond to dredging and disposal and identify any specific areas of concern.

Their study assesses:

  • Describes the existing environment
  • Discusses use of marine disposal areas for the dredged material
  • Any effects of increased current on sand migration around the open coast and within the harbour
  • Rate of sedimentation in the shipping channel and the need for on-going maintenance dredging.
  • Summarises predicted changes to hydrodynamics (waves/ tidal currents) and what these may mean for coastal processes and key features within the harbour.

Findings

Together with the independent experts we have been looking at how our proposed changes might affect coastal processes (things like tidal flows and wave conditions).

Thanks to extensive field work and hydrodynamic modelling, we’ve concluded that the proposed changes will have very little effect, or in some cases no effect, on the harbour in its current state.

Overall, any changes to tidal flows and wave conditions are small and consistent with the changes that already occur over time, and in some areas of interest – including on the ebb tide shoal and Mair Bank – no changes to existing coastal processes are expected.

We are also planning to put in place methods to mitigate any potential effects, such as choosing a disposal site for dredged sand that helps prevent future erosion of Mair Bank.

If you’d like to know more of the nuts and bolts of the effects these are outlined in the summary document here.

You can read further detail in the related downloads section below.

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