Underwater sound in the BSH
The BSH has extensive data sets from measurements of underwater noise within the framework of licensing and planning approval procedures, research projects and the conceptual design of national monitoring.
MarinEARS Information System
Since 2017, the BSH has been operating the specialist information system "MarinEARS", which currently contains the world's largest data set on impact pile driving noise events from monitoring during offshore construction. It is a scientifically and organizationally important tool to support the monitoring of noise abatement measures during the construction of offshore wind turbines.
Noise data is delivered to the BSH's specialist information system via a web-based exchange portal and can be processed into customized products for environmental assessments and reports. Thus it is possible to monitor and regulate the state of the seas with regard to underwater noise over short and long periods of time.
An important product is the annual reporting of impulsive noise events to the Regional Noise Register to fulfill the tasks arising from the implementation of the Marine Strategy Framework Directive (MSFD). The status of the annual impulsive noise delivery and further information and data on the reported noise events are available on the MarinEARS website under the topic Noise Registry.
Underwater noise from offshore projects
Offshore plants are often anchored in the seabed with steel piles. This is mainly done by ramming, but also by vibrating or sucking in. These activities generate impulsive or continuous sound, depending on the technical process.
The effect of sound sources on marine life depends on various components:
- The intensity, frequency, distance and time period of the source
- Hearing ability of marine species
- Distribution and habitat use of marine species
Noise protection requirements of the BSH
The BSH is responsible for the approval of offshore wind farms and grid connections in the German EEZ. In order to reconcile protection of the marine environment with the expansion of offshore wind energy, the BSH monitors the noise emissions generated by pile driving during offshore construction projects.
In 2013, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) developed a concept for the protection of harbour porpoise in the North Sea. The aim is to protect the habitats of the animals from impact noise by avoiding cumulative effects. The input of sound into the marine environment as well as the effective range can be greatly reduced by the use of technical noise abatement systems. Binding noise protection values apply to impulsive noise emissions from pile driving at a distance of 750 m from the source (binding in BSH approval notices since 2008).
Frequency-dependent reduction of the sound emission
Technical noise abatement systems, used individually or in combination, may reduce the sound exposure level (SEL) by more than 20 dB. The reduction in noise emission from pile driving depends on the frequency range. Reduction in higher frequency ranges (kHz range) is particularly important for the protection of harbour porpoise.
Noise reduction is achieved by using various techniques. These include the Big Bubble Curtain, the IHC Noise Mitigation Screen or the Hydro-Sound-Damper.