A geomorphological interpretation of multibeam data from the nearshore area between Belfast Lough and Cushendun, Northern Ireland

Gafeira, J.. 2010 A geomorphological interpretation of multibeam data from the nearshore area between Belfast Lough and Cushendun, Northern Ireland. Edinburgh, UK, British Geological Survey, 46pp. (CR/10/075N) (Unpublished)

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Abstract/Summary

This report describes a geomorphological interpretation of a multibeam echosounder dataset acquired offshore Northern Ireland, between Belfast Lough and the town of Cushendun. It is part of a Department of Enterprise, Trade and Investment (DETI) sponsored study aimed at gaining a better understanding of the distribution and thickness of subsurface salt layers expected to be present offshore Northern Ireland with the aim of assessing their potential for construction of caverns for storage of natural gas. Part of the study involved the acquisition of a high resolution 2D seismic dataset designed to image potential Upper Permian and Middle Triassic salt layers. The multibeam dataset was acquired in conjunction with the 2D seismic dataset and, despite this being a lower priority deliverable, good coverage was achieved due to the high density of seismic tracks and relatively deep water depth in this nearshore location. The multibeam data provides accurate measurements of the water depth in the study area and valuable information about the morphology and composition of the sea bed in the area. In the southern part of the survey area almost 100% coverage was achieved because of the close line spacing whereas in the northern part there are gaps between the multibeam data swaths. Although not specifically designed to acquire data to Admiralty Chart standard nonetheless the survey has made a valuable contribution to the knowledge of the seabed in this area which has applications in navigation, fishing, marine conservation and planning. The multibeam dataset, comprising bathymetric and backscatter information, was interpreted using ArcMap 9.3 GIS software. This allowed the use of appropriate surface analysis tools, such as slope and shaded-relief, to enhance the geomorphological interpretation. It also allowed the integration of the multibeam with other datasets held by the British Geological Survey (BGS). The multibeam dataset reveals the complex morphology of the surveyed seabed, which has been shaped by a development marked by tectonic, igneous, glacial and marine sedimentary events. The survey area contains parts of two renewable energy ‘resource zones’ identified in the Strategic Environmental Assessment report for the Northern Ireland Offshore Renewable Energy Strategic Action Plan. Tidal Resource Zone 2 (Rathlin Island and Torr Head) extends into the northern edge of the survey area and Tidal Resource Zone 3 (Maiden Islands) lies wholly within the survey area. Initial data interpretation presented in this report can be used to characterise the seabed but there is potential, with further ground-truthing by biological surveys, seabed sampling and shallow drilling, to produce maps of the seabed physical and biological habitats. Such maps would be invaluable as input into the planning and design of any future tidal energy infrastructure and as baseline data against which to measure the impact of this infrastructure.

Item Type:	Publication - Report
Programmes:	BGS Programmes 2010 > Marine Geoscience
Funders/Sponsors:	Geological Survey of Northern Ireland
Additional Information. Not used in RCUK Gateway to Research.:	This item has been internally reviewed, but not externally peer-reviewed. Report made open.
Date made live:	22 Jul 2021 13:30 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/530766

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