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Lough Swilly

Overview

Lough Swilly is located in Co. Donegal in the northwest of Ireland. The northern entrance to the lough is situated between the Inishowen peninsula to the east and the Fanad Head peninsula to the west. Letterkenny lies at the south of the lough. Lough Swilly is a glacial fjord and runs roughly north/south in a shallow “J”.

Location of Lough Swilly , Co. Donegal in northwest Ireland.

Photo of the coastline along Lough Swilly taken while surveying in 2014.

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INFOMAR Survey History

INFOMAR surveys of Lough Swilly consists of a lidar survey that was undertaken in 2010 by Pelydryn. The southern half of the lough is shallow and at low tide extensive mud/sand flats are exposed whilst the northern half is deeper and more conducive to LiDAR operations. In the northern half of the lough laser penetration up to and on occasions over 10m where achieved whilst in the south water conditions were poor with patches of suspended mud in the water column reduced the effective laser penetration.

Two surveys were carried out by the RV Keary and the Cosantóir Bradán in 2014.

Coverage from survey legs undertaken to survey Lough Swilly. (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

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Bathymetry (Water Depth)

Bathymetry of Mulroy Bay & Lough Swilly. (Click image for more detail)

All of our Charts for Lough Swilly can be downloaded in pdf format from this page.

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 Lidar 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 image of Mulroy Bay & Lough Swilly. (Click image for more detail)

All of our Charts for Lough Swilly can be downloaded in pdf format from this page.

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.

Click image for more detailed map.

Detailed .pdf backscatter charts can be downloaded by clicking here

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

Select your area of interest.Offshore Geotiffs - Backscatter Geotiffs. Take note of the survey names in INFOMAR Survey History.

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Ground Truthing/Seabed Sampling

INFOMAR have not carried out any sampling in Lough Swilly. However, sediment samples have been taken by Aquafact and others.

Locations of grab samples for Lough Swilly.

In 2014, we deployed a GoPro camera attached to the sound velocity probe and took some underwater images at Fanad Head.

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

Like Mulroy Bay, Lough Swilly penetrates inland through the ancient group of metamorphic rocks known as the Dalradian. However, due to its sheer length it acually passes southwards through two major sub-groups known as the Argyll and the Southern Highland groups (with the latter being the younger of the two). These rocks are very ancient and have suffered intense tectonic upheavals in the past, leaving them highly deformed, faulted and folded. Again like Mulroy Bay, at the entrance to Lough Swilly there are exposures of a younger, igneous rock called granite.

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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Shipwrecks

There is one shipwreck in this area, lying at the entrance to Lough Swilly. See the location on the Samples Map.

SS Laurentic by INFOMAR on Sketchfab   

To view the shipwrecks in Google and to download Shipwreck Information Sheets 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

The SS Laurentic features in Titanic Ocean Exploration Centre Interactive 3D Seabed Simulation demo by RealSim Movies.

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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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