25:["$","title",null,{"children":"Engineering Noise in the Marine Environment | Vekta Group | Observable"}] 49:T56b,Following last week's Insight about continuous noise, this week is exploring impulsive noise disturbances in marine ecosystems. Impulsive noise is characterised by short duration bursts of high intensity sound that can occur across a broad frequency range. Natural sound is important to many marine species for communication e.g. vocalisations and location of food and predators e.g. echolocation. Anthropogenic (human produced) noise can disrupt these processes and contribute to long term negative effects on individuals, populations and ecosystems.

Increasing marine infrastructure means that marine noise is increasing over time, putting additional pressure on marine ecosystems. There is growing concern of the impact of impulsive noise events, which tend to be more damaging than continuous noise, with international experts calling for government action to reduce anthropogenic marine noise.

Data for this week has been taken from the Marine Noise Registry (MNR). This dataset was established to keep a record of impulsive noise disturbances in UK waters, and was developed by the Joint Nature Conservation Committee (JNCC). The dataset includes activities that require licenses, which means that information regarding unlicensed or illicit activities is sparse, such as non-UK military sonar activities or acoustic deterrent device (ADD) usage at fish farms. 4a:T670,Impulsive noise data about wind farms was extracted to look for patterns of impulsive noise at different stages in the project life cycle. The chart below visualises these events for 2024.

Morecambe is the only wind farm recorded to use MBES in 2024. This technology is used in the earlier project phases to map and characterise the seabed, which can then determine foundation design and optimise cable routes.

Many offshore wind developments used SBPs during 2024. These are used in early to mid stages to identify important geological features such as sediment layers that will influence foundation design. For example, Bowdun plans to enter construction phase in 2029, and have used both SBPs that can penetrate up to 50 m of the seafloor and seismic surveys, which use higher energy sound sources to record up to thousands of metres underground e.g. for cable route planning.

The use of explosives at East Anglia Three were due to unexploded ordnance (UXO) - leftover explosives from WWII, of which controlled detonation had to take place before construction could begin. The East Anglia Three project also used MBES in 2024, but these were not submitted to the MNR as the frequency used was above the usual range for licensing.

Pile driving is used during wind farm construction to provide structural foundations before turbines can be installed. Pile driving was used by Moray West, which currently has the industry's largest turbines installed, using XXL monopiles. As shown on the chart, they used ADDs to deter marine mammals from the area during the period of pile driving to reduce risk of injury. 4b:T75e,Plot.plot({ height: 450, width: 1000, marginLeft: 90, marginTop: 0, x: { label: "Date", domain: [new Date("2024-01-01"), new Date("2024-12-3")]}, y: { label: "Offshore Wind Farm Project", tickSize: 0, grid: true}, color: { scheme: "Spectral", legend: true, opacity: 1 }, marks: [ // Bars for all events Plot.barX(data2, { y: (d) => d.project, x1: (d) => new Date(d.start_d), x2: (d) => { const start = new Date(d.start_d); const end = new Date(d.end_d); return end - start === 86400000 // If exactly 1 day, artificially extend ? new Date(start.getTime() + 43200000) // Add 12 hours for visibility : end; }, fill: "activity", fillOpacity: 0.8, bandWidth: 3, rx: 4, }), // Tooltip on hover Plot.tip(data2, Plot.pointerY({ y: (d) => d.project, x1: (d) => { const startDate = new Date(d.start_d); return startDate.toISOString().split('T')[0]; // Format to YYYY-MM-DD }, x2: (d) => { const endDate = new Date(d.end_d); return endDate.toISOString().split('T')[0]; // Format to YYYY-MM-DD }, title: (d) => `Block: ${d.project}\nActivity: ${d.activity}\nDays: ${d.pbd}\nOrganisation: ${d.regulator}\nStart Date: ${new Date(d.start_d).toISOString().split('T')[0]}\nEnd Date: ${new Date(d.end_d).toISOString().split('T')[0]}` })), // Y-Axis with line breaks between words if label is too long Plot.axisY({ anchor: "left", tickFormat: (d) => { const label = d; const maxLength = 10; const breakPoint = label.slice(0, maxLength).lastIndexOf(' '); if (breakPoint !== -1) { return label.slice(0, breakPoint) + "\n" + label.slice(breakPoint + 1)} else { return label} }}), ], })4c:T69c,Pile driving generates some of the loudest underwater noise during the wind farm project life cycle. Negative impacts can include auditory injury and behavioural disturbances in marine animals, as well as seabed habitat disruption. To explore data trends in pile driving, MNR data from 2014 onwards was used.

Each point on the graph represents an offshore wind project, with values for Sound Pressure Level (SPL), Sound Exposure Level (SEL), maximum hammer energy and number of pile driving events per project. The MNR reports SPL by peak sound amplitude, which is measured in decibels (db). Higher max hammer energy (cooler coloured points) corresponds with higher SPL. SEL accounts for both SPL and duration of noise, providing a broader picture of the disturbance's potential impact. Since the MNR does not include data about event duration, points are sized by number of events per project, which explains varying point size across SEL values. Whilst there is a positive correlation between SEL and SPL, this shows that there are other factors to consider.

Pile driving is the most common type of piling, but it is not the only one. Alternative foundation technologies, such as gravity-based and suction caisson designs, avoid the need for high impact impulsive noise. Mitigation techniques are also already implemented to reduce risks to marine life. These include ADDs and bubble curtains, which absorb and scatter sound waves to reduce transmission through the water. 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The table below shows the proportion of sectors that contributed to impulsive noise events during this year. Different organisations produce different impulsive noise activities, for example military sonar by the Ministry of Defence or civil engineering projects exclusively using pile drivers, compared to oil and gas exploration/extraction and offshore wind developments both using a variety of technologies that cause impulsive noise. \n\n| Sector | Percentage |\n| - | - |\n| Ministry of Defence | 41.1 |\n| Oil and Gas | 23.3 |\n| Civil Engineering | 11.6 |\n| Electrical Engineering | 11.6 |\n| Offshore Wind | 10.1 |\n| Carbon Capture & Storage | 1.5 |\n| Geological Consultancy | 3.1 |","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":718,"value":"$4a","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":132,"value":"$4b","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":19,"value":"## Pile Driving","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":24,"value":"$4c","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":234,"value":"Plot.plot({\n marginLeft: 50,\n width: 800,\n height: 500,\n grid: true,\n x: {label: \"Sound Pressure Level (db)\"},\n y: {label: \"Sound Exposure Level\"},\n color: {\n type: \"linear\",\n interpolate: t => d3.interpolateSpectral(1-t),\n legend: true,\n label: \"Max Hammer Energy (kJ)\",\n domain: [0, 4000]\n },\n marks: [\n Plot.dot(data3, {\n x: \"actual_sound_pressure_level\", \n y: \"actual_sound_exposure_level\",\n r: \"countifs\",\n fill: \"actual_max_hammer_energy\",\n fillOpacity: 0.3\n }),\n Plot.tip(data3, Plot.pointer({\n x: \"actual_sound_pressure_level\", \n y: \"actual_sound_exposure_level\",\n title: d => \n `Date of event: ${d.actual_date}\\nProject: ${d.Project}\\nOrganisation: ${d.lead_organisation}\\nSound Pressure Level: ${d.actual_sound_pressure_level}\\nSound Exposure Level: ${d.actual_sound_exposure_level}\\nMax Hammer Energy: ${d.max_hammer_energy}\\nType: ${d.activity_sub_type}`}))\n ]\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":9,"value":"
\n## Appendix","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":112,"value":"### Data","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":115,"value":"### What Noise?","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":593,"value":"windfarms = await FileAttachment(\"2024_pulseevents@3.csv\").csv({typed: \"auto\"})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"windfarms","database":"$undefined"},{"id":618,"value":"data2 = windfarms","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":13,"value":"### Pile Driving","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":404,"value":"piling = await FileAttachment(\"mnr_data_reported_2000-04-12-2025-12-31_2025-04-10@6.csv\").csv({typed: \"auto\"})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"piling","database":"$undefined"},{"id":161,"value":"data3 = piling","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":317,"value":"missingSummary = ({\n spl_missing: data3.filter(d => !(typeof d.actual_sound_pressure_level === \"number\" && !isNaN(d.actual_sound_pressure_level))).length,\n sel_missing: data3.filter(d => !(typeof d.actual_sound_exposure_level === \"number\" && !isNaN(d.actual_sound_exposure_level))).length,\n energy_missing: data3.filter(d => !(typeof d.actual_max_hammer_energy === \"number\" && !isNaN(d.actual_max_hammer_energy))).length\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":123,"value":"html``","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W4d","stdlib":"1"}} 24:null