7/27/2019 Environmental dependence of underwater sound propagation resulting from impact pile driving

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Environmental dependenceo underwater sound propagationresulting rom impact pile driving 

Tanja Pangerc1, Pete Theobald1, Lian Wang1, Paul Lepper2 and Stephen Robinson1

1National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK 2School o Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire, LE11 3TU, UK 

• Receptor position in the water column is an important consideration.• Sound speed proles, even in shallow water, can have a signicant inuence on acoustic propagation.

• Variation in sediment properties, typical to the North Sea, result in substantial diferences in acoustic propagation ranges or piling noise.

ReerencesAinslie, M. A., de Jong, C. A. F., Robinson, S. P. and Lepper, P. A. (2010) What is the Source Levelo Pile Driving Noise in Water? Proceedings o the 2nd International Conerence on the Efect o Noise on Aquatic Lie, Cork, Ireland, August, 2010.

Percussive pile driving, oten used to install oshore wind turbine oundations,

has the potential to radiate high amplitude sound into the water column.

The amplitude o the radiated sound will depend on both the sound sourcecharacteristics (e.g. requency, source level) and the propagation environment.

Consequently, variation between dierent oshore wind arms should be expected.

Environmental parameters inuencing the propagating may include:

• Bathymetry• Acoustic properties o the seabed

• Properties o the water column• Sea-surace statePropagation loss is requency dependent.

AIM: Illustrate, with modelling, the potential efect o seasonality and sediment type on underwater noise propagation, or common environmental conditions in the UK North Sea, in relation to pile driving.

Parameters considered:

• Typical parameters considered or the North Sea (East Coast o England)

• Seasonal sound speed data profles (WOA2005)

• Sediment: sand and gravelly sand

• Water depth kept constant (30 m) to reduce variables in the model

• Flat sea surace assumed to reduce variables in the model

• Sound source based on Ainslie et al. (2012)

Numerical propagation model: 

• Parabolic equation solution propagation model used - RAM(Range-dependent Acoustic Model) (RAMGeo, AcTUP V2.2L)

• Source level propagated in third octave bands

• Calculation o broadband pulse SEL

Spring Summer Autumn Winter

Spring Summer Autumn Winter

Constant depth and sound speed profle, variable sediment 

Constant depth, fxed sediment type (gravelly sand), variable sound speed profle

Gravelly

sand

Gravelly

sand

Sand