Galway Bay
Cuan Na Gallaimhe

Overview
INFOMAR Survey History
Bathymetry
Shaded Relief
Backscatter
Ground Truthing \ Seabed Sampling
Seabed Classification
3D Movie Flythrough
INFOMAR in Google Earth
Data Access

Overview

Galway Bay is a large bay located on the west coast of Ireland bordered by Co. Clare to the south and Co. Galway to the north. The bay is 62 kilometres long from the Brannock Islands in the west to Oranmore in the east. From Doolin to Lettermullan the mouth of the bay is 33 kilometres wide, but narrows at Black Head to 10 kilometres.

The bay is dominated and protected by the Aran Islands. The largest of which is Inishmore to the north, Inisheer to the south and Inishmaan between them. The main rivers entering the bay are the River Corrib at Galway and the Owenboliskey at an Spidéal. Along the south coast of the bay there are many minor freshwater inputs as well as submarine freshwater sources due to the drainage patterns associated with the karst landforms of the Burren.

Location of Galway Bay in the west of Ireland.

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INFOMAR Survey History

INFOMAR surveys of Galway Bay began in 2006 when Tenix LADS undertook a lidar survey of an area along the southern coast of the bay from Oranmore Bay to Black Head. This was followed by a survey on the Celtic Voyager which achieved exceptional success, covering a large area from the Aran Islands east beyond Black Head.

In 2007, IMAR Surveys Ltd. were contracted to undertake a hydrographic and geophysical survey of the inner part of Galway Bay. In 2008, another lidar survey was completed along the northern coast of the Bay and the eastern margin of the Aran Islands. Later in the year, the final gaps between lidar and earlier multibeam coverage were filled by the Celtic Voyager in the south of the bay off the Clare coast and along the eastern coast of the Aran Islands. This produced a seamless merging of previously acquired data into one comprehensive dataset.

Map showing the coverage from all surveys involved in mapping Galway Bay for the INFOMAR project. (Click image for more detailed map)

Details of surveys undertaken in Galway Bay. (Click image for more detail)

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Bathymetry

Bathymetry of Galway Bay. (Click image for more detailed map)

In general terms, to the east of Black Head water depths remain shallow with depths shallower than 20 metres. Indeed a large portion of the inner bay was suitable for lidar survey which is only typically effective in water depths of 15 metres or less in Irish waters. The bay gradually deepens to the west, with two distinctive areas of deep water between the Aran Islands and the mainland with water depths around 60 metres between Inishmore and Connemara, Co. Galway (the North Sound) and 50 metres between Inisheer and Co. Clare. There are also channels of deeper water between the islands themselves known as Gregory's Sound (between Inishmore and Inishmaan) and Foul Sound (between Inishmaan and Inisheer) where water depths around 30 metres were recorded in both.

Download more detailed bathymetric charts in .pdf format available at various scales here

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Shaded Relief

MBES shaded relief image of rock outcrops on the seabed north of Inishmore. The shallow area shown in red is known as the Brocklinmore Bank. The horizontal layers and jointed appearance of the rocks suggest that it is Carboniferous limestone, the same as that of the Burren and the Aran Islands. (Click image for more detailed map)

MBES shaded relief image of the seabed between Inishmore and Inishmaan showing a series of dynamic sedimentary structures including four large sand waves of which the largest measures 700 metres along the crest and 100 metres across. Northeast of Inishmore a series of smaller scale sedimentary structures are also visible. These origins of these bedforms may be formed by currents caused by the energetic movement of tides between the islands. (Click image for more detailed map)

Download more detailed shaded relief charts in .pdf format available at various scales here

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Backscatter

Image (left) of a MBES backscatter dataset where varying the various shaded of grey represent the intensity of reflected sound recorded by the multibeam sensors. The black areas are rock outcrops, with the darker grey areas around the outcrops and the lines that sweep off to the west probably represent coarser sediments which have been exposed or winnowed of fine sediments (light grey) due to tidal currents. The same image draped over the shaded relief image (right) shows more clearly the rock outcrops and the areas in dark green where sediments have been scoured and built up in the yellow, shallower areas. (Click image for more detailed map)

Download more detailed backscatter charts in .pdf format available at various scales here

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Ground Truthing/Seabed Sampling

A range of seabed sampling has been undertaken in Galway Bay, both historically and under the INFOMAR project. These include grab samples, vibrocores and video footage. The locations of the grab samples have been mainly determined by the seabed classification made from the multibeam data.

Seabed sampling locations from Galway Bay where Van Veen grab and Vibrocore instruments were used to ground truth INFOMAR datasets. (Click image for more detailed map)

In 2007, vibrocores were taken using the newly acquired GeoCore 3000/6000 in ideal conditions in Galway Bay. During the Celtic Voyager survey in the same year, 12 grab samples were recovered.

Using the RV Geo in 2008, 24 grab samples were recovered from the inner bay, primarily along the south coast. These are to be followed by further sampling by the Celtic Voyager in 2009 to gain sufficient samples to completely supervise the acoustic seabed classification.

Images of the vibrocores deployment (left) and the successful recovery of a core by INFOMAR staff in Galway Bay (right).

INFOMAR staff taking grab samples on the RV Geo in inner Galway Bay (left). View of Slievecarran (324 m) from the RIB showing the prominent limestone landscape of the Burren, Co. Clare (right).

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Seabed Classification

The classification of the multibeam dataset from Galway Bay resulted in the creation of a 5 class classification divided into two types of rock, reflecting the different textures observed from rock outcrops in the bay. Three more classes divided the sediments into Gravels and Coarse Sand, Coarse to Medium Sand and Fine Sand to Mud.

Seabed Classification Chart for Galway Bay.(Click on image for more detailed map)

Further information about the classification process can be found in the Data Processing section.

Download more detailed seabed classification charts in .pdf format available at various scales here

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3D Movie Flythrough

Click play below to view a 3D movie flythrough of the seabed of Galway Bay. The changing colours represent changes in water depth with red and orange for shallow water, yellow and green for intermediate depths and light and dark blue for deeper water. The flythrough begins with an overview, moves towards the eastern end of the bay before plunging beneath the surface and travelling along the south coast of Galway out to Lettermullan. It then rotates to the southeast and along the margin of the Aran Islands, over banks and patches before emerging just off the coast of Clare, near Doolin before panning back to an overview to finish.

The INFOMAR project acknowledges and thanks the United Kingdom Hydrographic Office (UKHO) for allowing the Admiralty Chart for Galway Bay to be used as a reference map for the area.

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INFOMAR in Google Earth

To view and navigate around the merged Galway Bay datasets in Google Earth, click here

To view and navigate around the 2007 Galway Bay Hydrographic Survey dataset in Google Earth, click here

To view and navigate around the 2008 Galway Bay Lidar dataset in Google Earth, click here

To view and navigate around the 2006 South Galway Bay Lidar dataset in Google Earth, click here

To view additional datasets in Google Earth please click here

Data Access

Full details outlining the process to gain access to datasets for the bay above or all INFOMAR data can be found in the INFOMAR | Data page of this website.

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Return to Survey Details Map

Follow these links to your area of interest on the INFOMAR website: