7. Physical Processes

7.1. Introduction

present the existing environmental baseline established from desk studies, site-specific surveys, and consultation with stakeholders;
identify any assumptions and limitations encountered in compiling the environmental information;
present the environmental impacts on physical processes arising from the Array and reach a conclusion on the LSE1 on physical processes, based on the information gathered and the analysis and assessments undertaken; and
highlight any necessary monitoring and/or mitigation measures which are recommended to prevent, minimise, reduce or offset the likely significant adverse environmental effects of the Array on physical processes.

Figure 7.1 Open ▸ illustrates the physical processes study area (Zone of Influence (ZoI)) for the Array which encompasses the:

proposed Array area (i.e. the area in which the wind turbines will be located); and
seabed areas that may be influenced by changes to physical processes due to the Array, based on the outputs of the physical processes assessment which will encompass a wider domain. This is the area of one spring tidal excursion, which is defined as the distance suspended sediment is transported prior to being carried back on the returning tide.

From published Admiralty data (United Kingdom Hydrographic Office (UKHO), 2023), a dominant current direction of north/south is evident and a mean spring tidal excursion of 8 km has been determined for these directions in the physical processes study area, reducing to 4 km for the east/west tidal regime. Figure 7.1 Open ▸ shows the physical processes study area relative to the nearest designated area relevant to physical processes, Firth of Forth Banks Complex Marine Protected Area (MPA), 25 km to the west of the site boundary.

Table 7.4 Open ▸ presents a summary of the key issues raised during consultation activities undertaken to date specific to physical processes for the Array and in the Ossian Array Scoping Opinion (Marine Directorate - Licensing Operations Team (MD-LOT), 2023) along with how these have these have been considered in the development of this physical processes Array EIA Report chapter. Further detail is presented within volume 1, chapter 5.

A range of existing studies and datasets has been reviewed and analysed to inform this physical processes baseline, in line with the process set out in the Array Scoping Report (Ossian OWFL, 2023). In addition, consultation with MD-LOT, MD-SEDD and NatureScot has been carried out to aid the collection of baseline information. Scoping responses did not specify any requirement for physical processes modelling of the baseline, however it was agreed with stakeholders, following review of the Array EIA Scoping Report, that the baseline assessment should also include water column processes. It was also agreed that four impact pathways should be scoped in and dealt with qualitatively, negating the need for physical processes numerical modelling of the baseline.
A qualitative approach has therefore been adopted, involving a detailed desktop review to gather baseline information on physical processes within the physical processes study area.

Information on physical processes within the physical processes study area was collected through a detailed desktop review of existing studies and datasets which are summarised in Table 7.5 Open ▸ .
Both the literature review of the reports and review of available data were used to characterise the baseline. The physical processes technical report (volume 3, appendix 7.1) includes full details of the analysis undertaken to develop the physical processes baseline.