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Shannon Estuary and Approaches

Inbhear na Sionainne agus Béal na Sionainne

 

Overview

The Shannon estuary is a large estuary on the west coast of Ireland where Ireland's longest river, the River Shannon enters the Atlantic Ocean. The estuary extends from Limerick City in the upper reaches out to the Mouth of the Shannon, an area between Loop Head, Co. Clare in the north and Kerry Head, Co. Kerry in the south. The mouth of the estuary is over 15 km wide, narrowing to just over 3 km between Kilcredaun and Kilconly Headlands. From the mouth to Limerick City the estuary is close to 100 km long following the central channel.

The relatively deep water and shelter from the Atlantic Ocean has led to the development of the estuary as a important centre for industry, imports and exports for Ireland. Large industries along the Shannon estuary include major power generation plants at Moneypoint, Co. Clare and Tarbert, Co. Kerry, bauxite refinery at Auginish, deepwater port facilities at Foynes. Import/Export goods and raw materials are carried on vessels up to 200,000 dwt in the estuary and illustrates the importance of safe navigation for these vessels making a strong case for the complete survey of the Shannon estuary by the INFOMAR project, particularly the navigable channel.

Ecologically, the Shannon estuary has a unique value with a group of bottle nosed dolphins resident in the estuary. As well as this, the estuary is an important habitat for migrating birds and wild fowl. The Shannon estuary is also an important recreational and tourist resource due to its location between two popular tourist areas in the Burren, Co. Clare and senic areas in Co. Kerry.

Location of Shannon Estuary and Approaches, west coast of Ireland.

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INFOMAR Survey History

The first INFOMAR survey of the Shannon estuary was undertaken in March 2009 when the Celtic Voyager mapped an area of the estuary extending from Foynes in the east out to the mouth of the Shannon and north of Loop Head. The final coverage for the CV09_01 leg was 167 square kilometres. In 2011 the Celtic Voyager returned and surveyed the mouth of the estuary. In 2013 the remaining areas and shallower water east of Foynes to Limerick was surveyed by the RV Keary, RV Geo and Cosantóir Bradán. (Click image for more detail)

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 some of the survey legs on our Blog by clicking on the link below.

INFOMAR mapping of the Shannon estuary

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Bathymetry (Water Depth)

Bathymetry of Shannon Estuary. (Click image for more detailed map)

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

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.

Overview image of multibeam echosounder shaded relief data collected in the Shannon estuary and approaches for the INFOMAR project. (Click on image for more detailed map)

Area of detail from shaded relief from an area around Loop Head showing spectacular folding and bedding in the bedrock outcropping on the seabed off Loop Head. The rock outcrops to the southwest show a different pattern of structure and texture suggesting that the rock outcrops on either side of the area of sediment cover are different rock types. (Click on image for more detailed map)

Shaded relief image of the across channel sand bar feature known as 'The Bridge' that lies on the seabed just west of Moneypoint on the Co. Clare side of the estuary. The surrounding water is around 20 to 30 metres deep but shallows to just over 6 metres at the crest of the sand bar. (Click on image for more detailed map)

Shaded relief image of the Shannon estuary at the location where the Killimer to Tarbert ferry crosses the channel. The image shows that west of Tarbert Island the channel deepens significantly. Another notable feature on the image is the pipeline or cable that runs northeast from the power station on Tarbert Island. Close examination of the seabed shows an abundance of sedimentary bedforms (sand waves, etc) suggesting the sediments on the seabed are being actively transported along the channel. (Click on image for more detailed map)

Shaded relief showing natural and man-made features on the seabed around Foynes Island. The long, straight feature to the west of the coverage is a gas pipe line that extends across the Shannon from the Above Ground Installation at Foynes. Sand wave formations north of the island are another interesting seabed feature shown in the dataset. These sinuous crested, bifurcating sand waves are probably the result of strong tidal currents operating in the estuary. (Click on image for more detailed map)

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

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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.

Overview image of multibeam echosounder backscatter data collected in the Shannon estuary and approaches for the INFOMAR project. (Click on image for more detailed map)

Download more detailed backscatter charts in .pdf format available at various scales 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 sampling was undertaken at the estuary mouth in 2011 by the Celtic Voyager and in Tralee Bay in 2015. Samples were taken by Aquafact in 2010. (Click image for more detail)

Sediment samples recovered from the seabed. Pebbles <4cm Coarse gravel and coarse shell hash and a sand sample (Click image for a 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

Shannon Estuary Geology
The Shannon estuary is bounded to the north and south for over half its length by sandstones and shales formed during the Carboniferous period, which then give way to limestone and shales further upriver.

The Bedrock datasets used in the Geology Map above are the Onshore Geology map Bedrock Geology 1:1 Million scale map produced by the GSI for the OneGeology project. It is available as a WMS. The Seabed geology map was compiled for WP4 of the EMODnet Geology project (lithology). It is available as a WMS and the Irish data can be downloaded as instructed below.

A more detailed 1:1 Million scale Geology map produced in 2014 which includes the offshore geology can be downloaded here (English)and Irish version here. A booklet "Understanding Earth processes, rocks, and the geological history of Ireland" which aims to aims to explain rock and landscape forming processes can also be downloaded.

Onshore Bedrock Geology shapefiles can be downloaded from our Interactive Web Data Delivery System (IWDDS).

On the IWDDS Select your area of interest. Vector datasets - Onshore - Bedrock

Offshore Geology shapefiles can be downloaded 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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INFOMAR in Google Earth

To view and navigate around the Shannon Estuary dataset in Google Earth, click on the link below.

Shannon Estuary

https://jetstream.gsi.ie/iwdds/delivery/INFOMAR_Google/INFOMAR%20Hydrographic%20Survey%20CV09_01_Shannon_Estuary.kmz

 

To view additional datasets in Google Earth please click here

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Shipwreck

Shaded Relief Image of the SS Premier. Download Shipwreck information leaflet Click here

To view the shipwrecks in Google please click here

Shipwreck 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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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.

Return to Survey Details Map

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

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