8c59bf28-c814-401b-8389-01ec414dffc3 English series series 2026-03-27T10:37:50 MEDIN 3.1.2 oceans Acoustic noise in the water column SeaDataNet Parameter Discovery Vocabulary 2023-12-12 revision Sound velocity and travel time in the water column SeaDataNet Parameter Discovery Vocabulary 2023-12-12 revision Operation and Maintenance The Crown Estate Renewable Energy Development Phases 2012-05-15 revision Renewable Energy Lease area The Crown Estate Renewable Energy Development Areas 2012-05-15 revision Energy resources GEMET - INSPIRE themes, version 1.0 2009-07-31 revision SeaDataNet sea areas 2012-11-07 revision English Channel SeaVoX Vertical Co-ordinate Coverages 2020-05-21 revision water column 2013-04-18T00:00:00 2013-05-20T23:59:59 1.831959 2.023934 51.730637 51.981616 2.58 38.90 TCE-440 Marine Data Exchange 2013, National Physical Laboratory, Greater Gabbard, Modelling of Underwater Noise Modelling of Underwater Noise 2021-05-17T13:37:54 publication English The Food and Environment Protection Act (FEPA) Licence (33097/07/0) for the Greater Gabbard Offshore Wind Farm (GGOWF) required the subsea noise during the operational phase of the wind farm to be measured to assess ‘various frequencies across the sound spectrum at a selection of locations immediately (adjacent to), within and outside the array at varying distances’. The full wording of licence condition 9.9 is stated below: ‘The Licence Holder must make provision during the construction phase of the wind farm to install facilities to enable subsea noise and vibration from the turbines to be assessed and monitored during the operational phase of the wind farm. Before completion of the construction phase the Licence Holder must specify how it proposes to measure subsea noise and vibrations to the Licensing Authority in order to fulfil the monitoring requirement outlined in Annex 1 attached to this Licence. The specification must include assessment of various frequencies across the sound spectrum at a selection of locations immediately, within and outside the array at varying distances.’ Although the licence condition sates ‘monitoring’ as a requirement, in situ measurements alone may not necessarily result in an increase of understanding of the potential noise resulting from GGOWF, compared with background or ambient noise in the area. Evidence from the Gunfleet Sands offshore wind farm (Nedwell et al., 2011) suggests that the type of wind turbine operating at GGOWF is not very ‘noisy’ compared with typical coastal ambient noise. This may particularly be the case around the GGOWF site where the density of surface vessel activity is relatively high. This report describes work carried out by the National Physical Laboratory (NPL), on behalf of Greater Gabbard Offshore Winds Limited, to assess the likely noise levels resulting from operation of the entire GGOWF, with a methodology that is considered most appropriate to address the underlying requirements of the relevant licence condition. There will be no limitations when published on the Marine Data Exchange otherRestrictions Data Must be used in accordance to the Marine Data Exchange's Terms of Use: https://www.marinedataexchange.co.uk/content/info/terms-of-use otherRestrictions The Crown Estate +44 020 7851 5000 enquiries@thecrownestate.co.uk custodian Dr Pete Theobald National Physical Laboratory +44 (0)20 8943 6888 pete.theobald@npl.co.uk originator The Crown Estate +44 020 7851 5000 enquiries@thecrownestate.co.uk distributor SSE Renewables caroline.thomson@sse.com owner asNeeded Documents https://www.marinedataexchange.co.uk/details/TCE-440/summary A link to the web service or dataset. https://www.marinedataexchange.co.uk A link to the general host site. Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08T00:00:00 publication Conformity with the Commission Regulation (EU) No 1089/2010 was either not relevant to this dataset or not a requirement of the Marine Data Exchange for the creation and submission of this dataset; therefore, conformity has not been assessed and cannot be declared False series To assess the underwater noise levels resulting from an operational wind farm, the single turbine source level was used as an input to an energy flux density underwater acoustic propagation model (based on Weston, 1976) for 140 turbine locations, each of which was placed on a grid measuring approximately 40 km by 40 km. For each turbine, each third octave band between 40 Hz and 1 kHz was propagated using a fully numerical, range dependent, propagation model which accounts for geometrical spreading and frequency dependent absorption (using Thorpe (1967)), surface scattering and seabed reflections. Each turbine grid used one second bathymetry data based on the lowest astronomical tide (LAT) and acoustic sediment data (Lurton, 2003), specific to each turbine location and based on the predominant sediment type identified in the area from the pre-lay survey (Gardline, 2009). This resulted in 140 grids, allowing the received level at each point to be incoherently summed to provide a map of the overall noise level resulting from 140 operating wind turbines. LAT was chosen following a comparison between LAT and the highest astronomical tide (HAT) to investigate the effect on propagation range. Whilst HAT normally results in the largest propagation ranges when considering receptors at a significant distance from the source, this is not always the case close to the source. At distances closer to the source, the shallow water channel can trap the acoustic energy, thus resulting in higher levels. Once the sound has propagated further from the source, the interactions with the seabed tend to dominate, which usually results in the reduced propagation ranges in the shallower water. However, for GGOWF, the turbine separation (approximately 1,000 m or less in most cases) is such that the highest received level reaching the neighbouring turbine occurs at LAT, and therefore results in the highest overall noise level within the wind farm array. A few kilometres beyond the wind farm boundary, the highest level may well occur at highest astronomical tide but at this range it would generally be within the expected ambient noise. SSE Renewables +44 (0)141 226 8916 info@sserenewables.com pointOfContact EPSG Geodetic Parameter Registry 2022-11-29 revision WGS 84