Abstract
As part of the research programme Wozep (‘Wind op zee ecologisch programma’), which investigates the ecological effects of offshore wind energy development in The Netherlands, TNO has been asked by Rijkswaterstaat (RWS) to:
-Investigate whether or not there is a need to incorporate the frequency
spectrum of the piling sound (pile driving at sea is needed during the
construction of offshore wind farms) in relation to the frequency sensitive
hearing in the assessment of the impact of these sounds on porpoises and
seals.
-Update the acoustic models (collectively known as Aquarius) that are being
applied in studies of environmental impact assessment for marine pile
driving projects.
The first point was addressed in a memorandum [de Jong & von Benda-Beckmann, 2018]. Though no firm conclusions could be drawn yet, it is likely that some form of frequency weighting will be incorporated in future impact assessment. The current report describes the update of the acoustic models (Aquarius). The goal of this update is to reduce the uncertainty in the calculated distances at which the piling sound in the North Sea could affect the hearing (TTS/PTS) of porpoises and seals or induce significant behavioural disturbance. The update concerns an attempt to improve various aspects in the modelling to reduce the uncertainties that have been observed in the Aquarius validation study [Binnerts et al, 2016].