Offshore Wind Sustained Observation Programme (OW-SOP): scoping report

6 Conclusions

This project aimed to provide recommendations for designing a programme focusing on sustained observations of physical and biogeochemical water column processes, to improve the evidence base and support the sustainable development of the OW industry within, but not limited to, the Scottish sector of the North Sea.

Based on a review of the current state of knowledge about the North Sea water column structure, previous and ongoing observational programmes and current efforts in understanding the interaction between fast-growing large-scale infrastructures and the ocean environment, this report provides a series of recommendations. These have been broken down into:

i. A set of recommendations for the fundamental EOVs to be collected at future observational/monitoring programmes at shelf-wide (regional) and site-specific (OWF project) scales, alongside recommendations around data collation and sharing.

ii. Recommendations on the use of existing modelling approaches and on their implementation to allow prediction of cumulative OWF-induced environmental impact(s).

iii. Recommendations for future observational/monitoring efforts and collaborative approaches.

Regarding points (i) and (ii), this report outlines that:

• Fundamental EOVs at a shelf-wide (regional) scale should include water column variables such as temperature, salinity, Chl-a, dissolved oxygen concentrations and growth-limiting nutrients. Atmospheric and metocean parameters including near surface atmospheric temperature, near surface wind velocity and waves should also be acquired, where possible.
• Fundamental EOVs at a site-specific (OWF project) scale should include water column variables such as temperature, salinity, Chl-a and dissolved oxygen concentrations, current speeds, suspended particulate matter and mixed layer depth. Furthermore, atmospheric and metocean parameters including near surface atmospheric temperature, near surface wind velocity and waves are also necessary.
• Existing data (including data from OW, O&G, EIAs, fisheries, etc.) should be collated, made publicly available and used to validate 3D models.
• 3D models should be used to understand the water column baseline conditions (in absence of OWFs), predicting the effects of natural variability and climate change. However, efforts should be made to improve existing model’s parametrisation to allow assessment of OWF-induced changes. Thus, existing and new data from observational/monitoring programmes should be used in conjunction with models to predict impact, but also to validate and refine models’ predictions.
• 3D far-field hydrodynamic models that take a precautionary approach to representing the mixing effects of OWFs could then be used at project scoping and EIA to assess the level of predicted mixing caused by the infrastructures.
• 3D far-field model results should be shared with developers, which would help with risk-management of developments whilst also providing guidance on pre-construction data acquisition needs. The precautionary 3D model could be then augmented by site-specific modelling performed by developers.

Regarding point (iii), this report outlines that future observational/monitoring efforts should:

• Integrate existing and innovative approaches to achieve a cost-effective and pragmatic acquisition of the EOVs specified above, including a combination of fixed, dynamic and/or remote platforms and sensors. Recommendation for sampling duration and temporal and spatial resolutions have also been provided in this report, where possible.
• Focus on getting measurements at the right time and location, by adhering to the following key principles when programmes are designed (focus on the period of stratification, spring/summer, monitor the transition zones where there is marginal water column stability or intermittent stratification and use this to parameterise and validate models).
• Prioritise sustained observations from fixed platforms at/near early OWFs in stratified waters.
• Consider the addition of CTD sensors to other planned, or existing, moorings (e.g. on marine mammal/passive acoustic detection moorings and eDNA samplings) in order to add value to moorings by opportunistic monitoring of physical water column.
• Ensure monitoring plans look beyond the project level and consider strategic sustained observations and methods to fund these e.g. governments and/or industry funded ‘sentinel’ monitoring stations collecting long time series data. Lease funds could be used for this purpose, and they could provide valuable data to validate and parametrise models.
• Ensure a link to existing sustained observation programmes (both national and international).
• Undertake workshops and JIPs aiming to address issues around model selection, data sharing and accessibility (data portals), data standard and formats (FAIR), definition of observational and modelling guidelines.
• Consider the latest technologies (e.g. MAS) for ongoing data collection. If instruments are to be added to OWF infrastructure, then developers and manufacturers should engage early to ensure this is included at engineering design.

Our recommendations stem from both the workshop discussions and the reviews of the current state of the field contained within this report. There was consensus from all participants in the review that measuring water parameters in relation to the potential for change in the stratification regime as renewable infrastructure develops in deeper waters is an important topic. All stakeholders agreed that the field is currently data deficient, and that monitoring is important, particularly to further understand field effects over time in the context of wider impacts such as climate change. There was general agreement that modelling has a key role to play, and that models should be iterative, undergoing continual refinement as data is collected over larger areas and timescales.

As the development of deeper water renewable infrastructure is still nascent, likewise the monitoring requirements will be expected to develop as the data available increases. Thus, there is a strong need for the definition of observational and impact modelling guidelines to be implemented pre-, during and post-development phases. Based on all the above, recommendations within this report should be continually reviewed and updated, using the state of art in procedures, as the industry expands.