The coastline of Siadar BayMott
MacDonald’s coastal team were responsible for assessing the coastal
environmental impacts of a proposed electricity generating
breakwater off the west coast of the Isle of Lewis as part of the
Environmental Impact Assessment (EIA).
The proposed devise uses the oscillation of the water column as a
wave passes to move electricity generating kit within the
breakwater, producing electricity from a renewable source. The
project will be among the first offshore electricity generating
breakwater schemes in the UK and is a demonstration project; a
scheme which will light the way for similar future projects and aid
in assessing the most suitable methodology for construction,
operation and decommissioning.
In order to assess the potential environmental effects Mott
MacDonald undertook a morphological impact assessment on the
coastline. We developed coastal evolutionary scenarios and assessed
potential morphological changes in conjunction with computational
wave modelling.
The project included field studies and geomophological mapping to
identify the units of the coastal system that could be affected by
the construction, operation and decommissioning phases of the
breakwater. Once the coastline was appraised in the field we used
empirical analysis to develop evolutionary scenarios with and
without the breakwater.
Mike 21 Model results for the Wave Agitation
study for including the case with a breakwater and partial
causewayThe impact of the proposed breakwater structure
on the prevailing wave climate was then assessed using the Mike21
wave modelling package to derive various likely wave scenarios. The
results from the wave modelling were used to correlate the existing
models and also consider the potential shelter benefits of the
breakwater to the existing slipway in the bay.
The study involved consultation with the local community including
the local ‘Pier Group’ (whose interest was the slipway landward of
the breakwater) the local fisherman’s group and a representative of
the local surfer’s association. Statutory Consultees included
SERAD, SEPA and the Comhairle nan Eilian Siar, the local council.
Applying advanced techniques in coastal projects
Evolutionary study of coastal sites
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