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Killary Harbour & Mannin Bay

Overview

Killary Harbour is a fjord located in the west of Ireland in the heart of Connemara which forms a natural border between counties Galway and Mayo. It is 16 kilometres long and in the centre over 45 metres deep.

Mannin Bay lies to the southwest of Clifden and is best known for it's maerl sands.

Location of Killary Harbour & Mannin Bay in the west of Ireland.

Killary Harbour

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INFOMAR Survey History

INFOMAR surveys of Killary Harbour began in 2005 when the harbour was surveyed to the extents allowable for a vessel the size of the Celtic Explorer.

In 2010, the RV Keary Leg 3 survey operations were focused in Mannin and Clifden Bays and the approaches to both, north of Slyne Head within northern extent of UKHO chart 2708.

The RV Geo & RV Keary focused their efforts on the areas of seabed around the islands of Inishbofin and Inishturk in 2012.

The RV Celtic Voyager, RV Keary, RV Geo and Cosantóir Bradán completed Killary Harbour in 2014. The RV Keary also surveyed the area south of Inishbofin.

Lidar surveys were carried out in Kilkieran, Bertraghboy, Ballyconnelly & Mannin Bays in 2010.

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

Survey Coverage polygons can be downloaded as a shapefile from our Interactive Web Data Delivery System (IWDDS).

Select your area of interest. Vector datasets - Offshore - Offshore Shapefiles

Read more about the Lidar survey on our Blog by clicking on the link below.

2010 LiDAR Surveying

KRY10_03 Clifden and Mannin Bay

KRY12_03 / GEO12_02 - Inishbofin, Inishturk & Killary Harbour

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Bathymetry (Water Depth)

Bathymetry of Killary Harbour. (Click image for more detailed map)

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

For a more detailed chart of the bathymetry of Killary Harbour click here

For a more detailed chart of the bathymetry of Mannin Bay click here

You can download Bathymetry xyz data from IWDDS

(Data Type: Vector Datasets, Region: Offshore, Theme: Bathymetry (Survey Leg) entire survey leg or Bathymetry (Survey Line) for individual tracklines. Take note of the survey names in INFOMAR Survey History.

You can also download the bathymetry data in ArcGIS GRID format

You can download Lidar xyz data from IWDDS

(Data Type: Vector Datasets, Region: Offshore, Theme: Lidar.

You can also download the bathymetry data in ArcGIS GRID format

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Shaded Relief

The 3D appearance is achieved using software called Fledermaus. By using some vertical exaggeration, artificial sun-shading (usually as if there is a light source in the nw 315°) and colouring the depths using various colour maps, it is possible to highlight the subtle relief of the seabed. This helps us to quickly understand the variation in depths.

Shaded Relief of Killary Harbour. (Click image for more detailed map)

Shaded Relief of Mannin Bay. (Click image for more detailed map)

For detailed charts of Killary Harbour click here

For detailed charts of Mannin Bay click here

Download Shaded Relief Bathymetry Geotiffs from our Interactive Web Data Delivery System (IWDDS)

Select your area of interest.Offshore Geotiffs - Bathymetry Shaded Relief Geotiffs.

Select your area of interest. Offshore Geotiffs - Lidar Shaded Relief Geotiffs.

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Backscatter

Multibeam Systems also collect additional information, including the strength of the acoustic signal (or return) from the seafloor. This is known as Backscatter. Differing seafloor types, such as mud, sand, gravel and rock will have different Backscatter values depending on the amount of energy they return to the sonar head. Rocky areas will typically have high returns while soft sediments like mud are more likely to absorb energy and have low Backscatter returns. These differing values are used to generate a grey-order image (i.e. dark for high returns, bright for low returns) of the seabed which can be used to examine the nature of the seafloor.

Backscatter image of Killary Harbour. (Click image for more detailed map)

Backscatter image of Killary Harbour. (Click image for more detailed map)

For detailed charts of Killary Harbour click here

For detailed charts of Mannin Bay click here

Download Backscatter Geotiffs from our Interactive Web Data Delivery System (IWDDS)

Select your area of interest.Offshore Geotiffs - Backscatter Geotiffs.

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Ground Truthing/Seabed Sampling

Some seabed samples were taken in Killary Harbour by the Celtic Explorer in 2005 and by the Celtic Voyager in 2015 in Mannin Bay. Samples were taken by Aquafact in Mannin Bay in 2010 and in Killary Harbour 2011. Samples were also taken by MERC Consultants around the Slyne Head peninsula in 2011.(Click image for more detail)

Sample locations can be downloaded as a shapefile from our Interactive Web Data Delivery System (IWDDS).

On the IWDDS Select your area of interest. Vector datasets - Offshore - Offshore Shapefiles

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Geology

Mannin Bay Geology
The geology of the Mannin bay coastline is ancient and complex. Most of the coastline is comprised of a deformed group of metamorphic rocks known as the Dalradian, which have seen episodes of tectonic unrest in the past, resulting in much faulting and folding, In the very north and southwest of the bay there are occurences of younger granite, an igneous rock that is also found in Connemara. The underwater expanse of craggy and fractured rock outcrop offshore, visible in the seabed data, seems to compiment the complexities of the geology onland.

Killary Harbour Geology
Known as “Ireland’s only Fjord”, Killary Harbour is a dramatic feature. The seabed data shows that it is deepest towards its entrance, becoming shallower inland towards the village of Leenane. It was carved by glaciers during the last Ice Age. The ancient bedrock geology to the north is comprised of sedimentary rocks known as greywackes, sandstones and shales. Mweelrea, Connaught’s highest mountain, is located on Killary Harbour’s north coast.

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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:

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