Home | Links | ©| Contact Us

Broadhaven Bay

Overview

Broadhaven Bay is located on the Atlantic coast, north Co. Mayo in the north-west of Ireland. It is open to the North Atlantic at its northern end. At its southern end it narrows at Belmullet and is linked to Blacksod Bay by a narrow man-made channel.

Back to Top

INFOMAR Survey History

The Celtic Voyager mapped a large portion of the deeper water in 2002. The RV Geo, RV Keary and Cosantóir Bradán focused their efforts on the shallower waters in the bay in 2010, 2011 and 2014.

A Lidar survey was completed in 2010 by Pelydryn. The seabed is predominantly sand and good laser penetration and returns were experienced throughout the Bay. Survey lines were extended outside of the Bay itself in order to give an area of overlap with existing multibeam surveys.

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

Back to Top

Bathymetry (Water Depth)

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

In general terms, the bathymetry of the area is as expected with relatively shallow areas within the bays which deepen moving offshore. Water depths range from 0 metres to 100 metres offshore.

For a more detailed chart of the bathymetry of Broadhaven 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

Back to Top

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.

Click image for more detailed map.

All of our Charts for Broadhaven 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. Take note of the survey names in INFOMAR Survey History.

Back to Top

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.

Back to Top

Ground Truthing/Seabed Sampling

To verify the results of remotely sensed sonar data, it is important to collect physical sediment samples from the seabed. These may be from the surface where grabs are used or may penetrate through the seabed and retain the vertical structure of the sediment by using various coring methods. These samples are also critical for the confirming seabed classifications.

The RV Keary took 13 grab samples (red circles)in Broadhaven Bay in 2014. All the samples were sand.Full Particle Size Analysis (PSA) was carried out on the samples.

22 samples (yellow triangles) were taken in Broadhaven Bay in 2009 by the Marine Institute. Most of the samples were Sand. 5 were Slightly Gravelly Sand Full PSA was carried out on the samples. 33 samples (green triangles) were taken in Broadhaven Bay in 2012 by the Aquafact mainly using a grab sampler and a couple using a Van Veen grab smapler. The majority (19) were 'Slightly gravelly sand' and the remainder were sand (14). Full PSA was carried out on the samples.

Offshore sampling (64) was taken using a vibrocorer in 2010 by the Celtic Voyager (blue circles). Geotechnical only with no PSA carried out. The Celtic Voyager also ran a sampling campaign (red circles offshore) in 2002. 7 of the samples can be seen in the image. The 4 samples in the top right of the image with dark backscatter are Course sand and gravel.

Click image for more detailed map.

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

Back to Top

Geology

Broadhaven Bay Geology


Broadhaven Bay’s coastline is predominantly composed of an ancient and deformed set of rocks called the Dalradian.

The parts of the Dalradian represented here include metamorphic rocks like schist and quartzite, that have experienced dramatic tectonic upheavals in the past.

The complex folding and faulting of all these ancient rocks can be seen extending onto the seafloor in the INFOMAR seabed data.

Folded bedrock NE of Broadhaven Bay, around Knife Rock.

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

Back to Top

INFOMAR in Google Earth

Image of Lidar data for Blacksod Bay in Google

Download the bathy lidar Achill Blacksod Broadhaven 10m dataset.

To view additional datasets in Google Earth please click here

Back to Top

View data in the free iView4D

Download the free viewer here

Download the Achill Blacksod Broadhaven 10m dataset here

 

Back to Top

Return to Survey Details Map

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

About | Surveying | Data & Products | News & Updates | Press Releases | Publications | Associated Projects | Image Gallery | Contact Us | Home

 

Find Us
Geological Survey of Ireland Geological Survey, Ireland
Beggars Bush, Haddington Road
Dublin 4
Marine Institute Marine Institute Headquarters,
Rinville, Oranmore
Co. Galway
The National Development Plan
a modus site