German Federal Agency for Nature Conservation (BfN)

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Minimisation


There are numerous technical approaches which can be applied to minimise underwater noise and reduce sound emissions (see below). Nonetheless, generally applicable measures are needed if underwater noise is to be controlled on an ongoing basis and, more importantly, damage caused to marine life kept to an absolute minimum. While the designation of protected areas and regulation of shipping activities are steps in the right direction, more must be done.

Solutions

The following solutions (especially in respect of wind farm construction) should be pursued and maintained:


  • Careful selection of sites taking into account the risk potential for marine life – especially protected and specially protected species.
  • Spatial coordination of construction projects to ensure the availability of retreat areas, especially for harbour porpoises.
  • Temporal coordination of construction projects to ensure that harbour porpoises are not disturbed during sensitive periods in which they mate and calve.
  • Noise pollution regulations: noise emissions should not be allowed to exceed a certain level in order to prevent injury and behavioural changes.

The creation of underwater noise maps is an effective tool with which to identify noise pressures and assess the effectiveness of the measures outlined above.

Technical solutions

Bubble curtain to minimise noise propagation. Photo: Trianel
Bubble curtain to minimise noise propagation. Photo: Trianel

Technical solutions used for noise minimisation are gaining in importance, particularly in respect of marine construction projects. Because the decisive conditions such as water depth and seabed properties can vary from site to site, finding a generally applicable technical solution can be problematic.

There are, however, noise reduction solutions – such as the use of a bubble curtain – which prevent or limit sound propagation. Alternative technologies used in building foundations are also available, but these have yet to be tried and tested in practice.

With regard to seismic surveying, alternative solutions such as the marine vibroseis system are also an option.

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