Acoustic ground truthing of airgun noise in Chatham Rise, New Zealand

• Published in: The Journal of the Acoustical Society of America 2016-10, Vol.140 (4), p.3172-3172
• Main Author: Cheong, Sei-Him
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4969965

Underwater noise is a growing concern to conservation of the marine life. Noise generated by seismic survey in particular is recognised as a significant and pervasive pollutant, with the potential of impacting the marine ecosystem. Between the 1st February and 21st March 2016, a geophysical research survey was conducted in Chatham Rise, New Zealand, to collect seismo-acoustic data using a Sercel Sentinel seismic streamer in order to ground truth the underwater noise impact assessment, conducted according to the Department of Conservation (New Zealand) 2013 Code of Conduct. Data were analyzed in order to determine the received sound level at a distance up to 3 km from the seismic source array. This paper establishes the method to predict the mitigation impact radii from seismic data in order to validate the results obtained based on predictive noise modelling using Gardline 360M model. The study was also aimed to provide confidence to the capability of predictive modeling for estimating the acoustic impact zone of a seismic sound source. Data showed that seabed reflection can fluctuate significantly according to sediment topography and other environmental influences; however, a very consistent trend can be obtained from direct propagation to confidently establish mitigation radii. Results show that the employment of a seismic streamer for the establishment of effective mitigation radii is technically feasible and may be used as a tool to ground truth predictive modelling as part of a marine mammal mitigation plan.