Scottish Marine and Freshwater Science Volume 3 Number 2: Scoping Study For Offshore Wave Energy Development In Scottish Waters

3 Structures of the Models Used

As described in the documentation supporting The Strategic Environmental Assessment for Offshore Wind (Scottish Government, 2010a), and as is normal in the use of MaRS, the data layers had been classified as either exclusion layers ( i.e. indicating areas where development was not appropriate), or constraint layers ( i.e. indicating the distribution of factors that acted as partial constraints on development). The constraint layers were each allocated a weighting. Within each constraint layer, the data had been assessed through a scoring scheme. The constraint layers were allocated either to technical resource assessment or to a non-Technical Model. The non-Technical Constraints Model was comprised of the outputs from three thematic Restriction models, covering constraints arising from industrial activity, environmental factors, and socio-cultural interests. The socio-cultural layer is broad in its scope, covering visual and recreational factors as well as historical heritage and archaeological potential. The outputs of these models had been normalised against the Exclusion Model.

The data layers which were included in the various models were as follows:

3.1 Socio-cultural Restriction Model ( MaRS ref. 2569)

3.2 Environmental Restriction Model ( MaRS ref. 2570)

3.3 Industry Restriction Model ( MaRS ref. 2566)

3.4 Non- technical Exclusion Model ( MaRS ref. 2567)

The following features were treated as incompatible with wave farm development, i.e. areas covered were used to create an overall special model of areas from which wave farms should be excluded at this time.

All Offshore Cable inside UK Waters
All Pipeline in UK Waters (active)
Anchorage Areas
Aquaculture Leases - Current
Aquaculture Leases - Pending
Waste disposal sites (open)
IMO Routeing - excluding ABTAs
Munitions Dumps
Navigation aids
Offshore Shipping Zones
Offshore Wind Farm Demonstration Sites
Operational Anemometers in UK Waters
Protected Wreck Exclusion Buffers
UK offshore wind activity
Shipping Density - Exclusion Areas
Tidal Leases - Live
UK Deal oil and gas Safety Zones
UK Deal oil and gas Surface features
UK Deal oil and gas Subsurface features
UKCS Exclusion Buffer - 500 m
Wave Leases - Live
UK Detailed Coastline - not including Isle of Man (Polygon)

3.5 Wave Power Resource Assessment

Wave power resource was assessed in terms of the power density (kw/m), and limited to depths of water of less than 200m. The former provides an indication of the available energy, to ensure that the necessary wave power is available at a potential development site, while the limitation to less than 200m reflects extent of the continental shell, which is anticipated to be the initial potential scope of development.

The resource assessment therefore excluded areas where there was considered to be insufficient wave energy resource (20 kw/m) for commercial scale developments, and also areas where the water depth was less than 10m or greater than 200m.

The outputs from the restriction models, after normalisation against the exclusion model, should be viewed in the context of technical (resource) opportunities and constraints of the areas under consideration.

3.6 Improvements to the Previous Spatial Modelling

The use of MaRS to develop Scoping Studies for marine renewable energy has been characterised by progressive improvements in the available data, and the data handling. Some significant differences from, and additions to, previous models have been implemented in the current exercise. The main improvements made were:

1. Landscape and visual issues: Develop a buffering system around national scenic areas ( NSA), local coastal landscape designations, and other coastal areas to reflect the relative importance of landscape in different coastal areas, and the decreasing visibility of wave power devices with distance from NSA boundaries and other areas of coast.
2. Surfing beaches. There is some potential for wave energy devices close to the coast to affect the wave spectrum reaching the coast, and this in turn may affect the suitabiloity of coastal areas for surfing. The locations of surfing beaches were taken from National Marine Plan interactive ( NMPi), the data underlying the development of Scotland's Marine Atlas (Scottish Government, 2011a) and buffered to a distance of 10 km.
3. Commercial fishing: A separate MaRS model was created for the commercial fishing sector. Within that model, landings from smaller vessel operating within STW, and landings from >15m vessels ( i.e. those covered by the Vessel Monitoring System) were identified and distinction was made between static and mobile gears. In inshore waters, landings were partitioned between internal waters, 0 - 6 miles, 6 - 12 miles, and landings from greater distances within ICES statistical rectangles that also include areas within STW were identified. Based on current wave project design plans, is likely to be difficult to operate commercial fishing activities, using either mobile or static gear, within the footprint of wave farms. In combining the commercial fishing data into a single layer, the four combinations of inshore and offshore vessels, mobile and static gear, were therefore given the same weight.
4. The offshore wind Scoping Study gave considerable weight to factors related to aviation. These factors are omitted from the current study, as interactions between wave farms and aviation are likely to be insignificant.
5. A additional data layer was included in the industry model to take account of the many navigational aids in both inshore and offshore areas.
6. Potential for archaeological heritage remains on the seabed: Maps indicating areas of the current seabed which had been exposed as land at some time since the Ice Age (and had high potential and theoretically high potential for marine archaeology) were combined with maps of seabed sediment type and structure to identify areas of seabed where potential for archaeological remains coincided with favourable seabed conditions. This layer had initially been used in the wind Scoping Study (Davies and Watret, 2011), and was carried forward into the current study.
7. Sensitivity of areas to seabirds: An initial approach was made to developing indices of the relative sensitivity of sea areas for vulnerable seabirds. Collision with wave energy devices is likely to be minor risk to seabirds, but disturbance during construction and operation may be of greater concern. Mapped data on the distribution of 17 SPA species of sea birds at sea during the breeding and winter seasons (European Seabirds at Sea survey, JNCC) were expressed in terms of the total Scottish population of each species. These distributions were combined to give an overall expression of the relative sensitivity of sea areas in the winter and in the breeding season.
8. Disturbance of seals at sensitive periods in their life cycle may arise from the construction and operation of wave farms in coastal waters. Following from the Marine (Scotland) Act 2010, preliminary work has been carried out to identify important seal haul out and breeding sites around Scotland. A data layer was created showing haul out sites for both grey and harbour seals, and buffers created out to 30 km.
9. Sensitivity of areas to marine mammals: Data from the JNCC cetacean atlas of the distribution of marine mammals at sea were scaled to the Scottish populations of each species and then summed to express the overall importance of sea areas to marine mammals.
10. Spawning and nursery areas: Maps derived from Coull et al. (1998) showing areas of spawning and nursery grounds for 14 commercial fish and shellfish species were gridded and combined to show counts of spawning species or nursery ground species within each grid cell. The resulting layers were scored and weighted.
11. Designated areas for the protection of birds: There are a number of different designations for marine or coastal areas for the protection of birds, including RAMSAR sites, SPAs, SSSIs, RSPB reserves, local reserves, IBAs etc. In many cases, areas hold more than one designation, and treating each form of designation independently (as was done in the Saltire Prize Scoping Study) resulted in potentially multiple counts of the same area for the same environmental sensitivity (birds). The data were therefore processed such that only the most important designation of any particular area was included in the final data layers, for example an area designated at European, national and local levels would be considered as designated at European level, whereas an area designated at local level only would be scored as a local designation.

Of the suggestions made in previous reports, for improvements to underlying data, almost all were achieved and further additions made. Exceptions were:

a) that SACs were not filtered for sensitivity to wave energy developments.

b) the distribution of SNH Priority Marine Features ( PMF) was not taken into account. A significant amount of work will be necessary to convert the available information on the distributions of PMFs into a form suitable for inclusion in spatial modelling.