318. The worst case changes in terms of the tidal regime due to the presence of largest foundations (Table 7.3 and Table 7.7 ) are likely to have the following magnitudes of effect (Table 7.27):
Table 7.27Magnitude of effects on the tidal regime due to the presence of foundations under Worst Case Scenario.
Location
Near-field Far-field
Scale Low No change Duration
High -
Frequency
Medium -
Reversibility Magnitude of Effect
Negligible -
Low No change
319. These effects on the tidal regime have been translated into a ‘zone of potential influence’ based on an understanding of the tidal ellipses. It is expected that changes to the tidal regime would have returned to background levels well within the excursion of one tidal ellipse, and this threshold has been used to produce the maximum ‘zone of potential influence’ on the tidal regime, as presented in Figure 7.6.
320. The identified receptor groups for marine geology, oceanography and physical processes are remote from the ‘zone of potential influence’ on the tidal regime. Due to this, no pathway exists between the source and the receptor, so in terms of impacts on these receptor groups there is no impact associated with the proposed project.
7.6.2.2 Impact 2: Changes to the wave regime due to the presence of foundation structures
321. The presence of foundation structures within the East Anglia THREE site has the potential to alter the baseline wave regime, particularly in respect of wave heights and directions. Any changes in the wave regime may have the potential to contribute to changes in the sea bed morphology due to alteration of sediment transport patterns (see Impact 3, section 7.6.2.3) or due to initiation of sea bed scour (see Impact 4, section 7.6.2.4).
322. Expert-based assessment suggests that each foundation would present an obstacle to the passage of waves locally, causing a small modification to the height and / or direction of the waves as they pass. Generally, this causes a small wave shadow effect to be created by each foundation. Wave heights return to baseline conditions with progression downstream of each foundation and generally do not interact with effects from adjacent foundations due to the separation distances.
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm Chapter 7 Marine Geology, Oceanography and Physical Processes Page 63
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