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The Maidens (including the North and Outer Klondyke) are a group of bedrock extrusions about 14 km northeast of Larne, off the coast of Northern Ireland (central point for Maidens Complex: 54°57'50.0, 25°42'20.0). Multibeam echosounder data have been combined with extensive ground-truthing to produce broad-scale substratum and biotope maps for the site. The bathymetry was used to derive rasters of slope gradient, rugosity, aspect, and fine- and broad-scale benthic position index which were used for further analyses with Principal Components Analysis. Ground-truthing data were used to create sample signatures and a Maximum Likelihood Analysis performed to classify the surfaces according to that signature. The supervised classifications generated distributions for three broad-scale substrata and habitat biotopes (six level three biotopes, four level four and one level five biotope). The maps provide critical information and distributions that greatly facilitate the conservation, management and monitoring of a proposed Special Area of Conservation. [ABSTRACT FROM AUTHOR]

A 1:30,000 substratum map for an area off the north coast of Ireland is presented. The study area is bounded in the south by the Causeway coastline and in the north by the following coordinates: top left corner (6°43'36''W, 55°17'N) and top right corner (6°27'W, 55°17'N). This mapping has been made possible through the availability of full seafloor coverage multibeam swath bathymetry and backscatter data (both gridded to 1 m), together with ground-truthing data collected over the past 40 years. Bathymetry data were used to generate terrain indices such as slope, rugosity, aspect, fine- and broad-scale Benthic Position Index, whilst the backscatter data were interpreted visually, subjected to an unsupervised classification process using QTC Multiview, and combined with the bathymetry-derived parameters into a clustermap in ArcGIS. The resulting maps allowed us to divide the seabed into 10 distinct acoustic classes, which, linked to sediment samples, diver surveys, underwater video-tows and remotely operated vehicle surveys, were converted into a substratum map. This is the most accurate seafloor substratum map to date for the north coast of Ireland and could form the basis for more in-depth geological, biological and hydrodynamic studies of this highly dynamic coastline. [ABSTRACT FROM AUTHOR]

This paper outlines work currently being undertaken to reconstruct submerged archaeological landscapes off the north coast of Ireland. This research uses the recently-completed Joint Irish Bathymetric Survey (JIBS), which has provided full-coverage high-resolution multibeam bathymetric data for the sea-bed off the north coast. This data has been examined for evidence of past sea-level change and been used to produce palaeo-geographic reconstructions of the past landscape, which in turn have facilitated the identification of ten areas of high archaeological potential. The results presented here will form the basis of a future programme of archaeological survey and prospection. © 2010 The Authors [ABSTRACT FROM AUTHOR]

This paper describes Phase 1 of the project 'Archaeological Applications of the Joint Irish Bathymetric Survey (JIBS) Data', analysing bathymetric and backscatter data derived from multibeam surveys off the north coast of Ireland. In particular, the usability of the data for shipwreck detection, identification and site characterization is explored. In Phase 1, the data was screened for anomalous sea-bed features, which were subsequently described, catalogued and categorized according to their archaeological potential and cross-referenced against existing records. A planned second phase of this project will examine each anomaly in greater detail together with the local and regional hydrodynamic conditions. © 2010 The Authors [ABSTRACT FROM AUTHOR]

Please clickhereto download the map associated with this article. Multibeam echosounder data collected by the Irish National Seabed Survey (INSS) between 2000 and 2001 in the Rockall Trough have been used by many projects to analyze the geomorphology and the sedimentary processes of the margins of the Trough. However, due to the low spatial resolution of 150–250 m and the amount of artefacts still embedded in the publicly available data, many geomorphological features have been overlooked. This paper shows that the same multibeam dataset can provide more detailed information on seabed processes when the latest hydrographic and backscatter post-processing techniques are used to reduce data artefacts and improve data quality and spatial resolution. The resulting map, presented here at a scale of 1:450,000, is based on a semi-automatic and manual interpretation of geomorphological features highlighted using a new and improved 30 m bathymetric grid and a multibeam backscatter mosaic obtained using the GEOCODER post-processing algorithm. Overall, the map shows a complex sedimentological scenario where the Rockall Bank Mass Flow failure, the Donegal-Barra trough-mouth fan, along slope structures such as the Feni Contourite Drift and the Porcupine moat dominate the Rockall Trough flanks and basin floor. Smaller features such as canyon and gully systems, escarpments, coral mounds, volcanic mounds and iceberg scours have also been mapped in detail. In addition, the interpretation of the backscatter mosaic allows for the first time the identification of depositional lobes generated by downslope mass transport and canyon drainage systems, particularly where these features completely lose their bathymetric expression. [ABSTRACT FROM PUBLISHER]

Efforts to develop a procedurally robust method for automated classification of multibeam backscatter have taken a variety of approaches (e.g., image-based, textural, angular range analysis). For image-based classification, little research has focused on the roles of operational parameters of vessel and sonar system in affecting the final classification. Repeat multibeam surveys (2005 and 2006) conducted at the same area with different sounding densities were classified using QTC-Multiview. Comparison of class areas revealed 78% agreement between classifications derived from the two surveys. Cross-tabulation of ground truth video and class demonstrate 71% agreement in the low-density survey and 77% for the high-density. Differences between classifications are primarily attributed to variation in along track data density, errors in the compensation process, and/ or insufficient quality control of the input data. Natural change detection at the scales observed was determined not to be practically discernable from the errors associated with the classification process. [ABSTRACT FROM AUTHOR]