Modelled Mapping of Continuous Underwater Noise Generated by Activities.

Abstract

This report on underwater noise in the South marine plan areas has been prepared by ABP Marine Environmental Research Ltd (ABPmer) on behalf of the Marine Management Organisation (MMO). Quantification of underwater noise is a current and evolving topic in marine environmental science that is relevant to marine plan policy development. It is recognised that there is currently insufficient data to support a quantitative assessment of underwater noise levels and its impact on the natural environment at marine plan or national scale. This research and development work represents an initial step in addressing the recognised gap in availability of consistent plan scale indicative map(s) of anthropogenic underwater noise distribution and levels to support marine planning. A data and literature review of academic journals, government, non-government organisations and industry reports identified a wide range of marine noise sources. It found vessel traffic, fishinthis can be presented as g, and dredging to be the principle anthropogenic continuous noise sources relevant to the South plan areas. Indicative maps can inform sustainable development through improved awareness and consideration of continuous underwater noise in impact assessments, especially in relation to protected and commercially valuable species. This work resulted in the development of a reusable GIS tool that enables quantitative modelling of underwater noise by taking into consideration relevant quantification and transmission loss concepts. In addition the report identifies the principle sources of continuous anthropogenic marine noise. The report also documents the tool and how it can be used to produce improved indicative maps as new data becomes available. The GIS tool is based on a simple sound transmission model and produces a grid of annual exposure hours at different sound pressure levels; this can be presented as a spatial map or a frequency histogram for one or more grid cells. It uses noise source values identified in the literature review in combination with Automatic Identification System (AIS) shipping category density data, Electronic Monitoring System (EMS) aggregate dredging data and Vessel Monitoring System (VMS) fishing data which are consistent at the plan scale. The GIS tool outputs are indicative only and should not be used as a basis for specific environmental impact assessments. There are a number of limitations and caveats associated with the GIS tool output, these relate to output confidence in different conditions and the nature of the available source activity data. Several recommendations have been made for the further development of the GIS tool, these include updates that would allow the GIS tool to be used beyond the South marine plan areas, and additional work that would most effectively improve accuracy of the output.