INFOMAR reports on a successful survey season - 2013

V. Quinlan, K. Sheehan, F.Sacchetti

INFOMAR continued its survey activities in the south of the country into August. During this survey period INFOMAR completed the important South Priority Area (SPA) which stretches from near Toe Head in the southwest to Carnsore Point in the northeast.
RV Celtic Voyager operations commenced in Clonakilty Bay off the Cork coast in early July and for a period of four weeks seabed mapping continued into Glandore Bay, Baltimore Bay, Long Island and Roaring water Bay and a number of smaller bays in this region.


Figure1. Extent of Multibeam coverage during July & August 2013

The survey area included the important Special Area of Conservation (SAC) for marine mammals which encompasses Roaring water and Long Island bays. Mapping within the SAC requires a special license agreement, which was granted by National Parks and Wildlife Service (NPWS). The survey was conducted during day light hours exclusively, in compliance with the Code of Practice for the Protection of Marine Mammals during Acoustic Seafloor. Ports of significance in the area include Crookhaven, Schull, Baltimore, Cape Clear and Glandore. Water depths range from 10 to 100 meters.
Strong currents, shoals, and fishing gear made for exciting times mapping the Gascanane sound which separates Cape Clear and Sherkin Islands. This sound is regularly used by the Baltimore to Cape Clear ferry and by numerous fishing boats and pleasure crafts.
The seabed in the sound is extensively scoured by strong tidal currents, forming impressive holes of up to 50 meters depth.


Figure 2. Bathymetry image of Gascanane sound with scour holes evident.

Favorable weather periods were utilised to survey close in to the iconic feature that is the Fastnet rock. Survey data from both the Geological Survey of Ireland vessel; RV Keary and RV Celtic Voyager were required in order to map this area safely and to acquire full coverage.


Figure 3. Fastnet Rock (Photo courtesy of Nicola O'Brien)

Bad weather conditions on 31st July meant an unscheduled portcall in Castletownbere (figure 4), County Cork. Castletownbere is the biggest fishing port in the south of Ireland. Figure 4 shows the inner harbour. The weather downtime allowed the data processors to get through a backlog of processing and for the crew to do some maintenance and painting that they don’t get the opportunity to do while at sea.


Figure 4: Castletownbere Harbour.

Wrecks
A total of nine wrecks were mapped. Figure 4 below is an image of a wreck discovered on this survey. This wreck is previously uncharted and appears to be that of a submarine. This is currently under research, the outcome will no doubt be an interesting story. All the wrecks are initially identified from the main multibeam survey lines and are then mapped in detail using a 'box in' process of three parallel lines and one perpendicular line. Multibeam water column data is also acquired in order to maximize the mapping effort and ensure that small objects such as masts are also mapped. This effort produces the detail required both for identification and charting purposes.


Figure 4 A possible submarine.

The survey demobilised in Galway on 7th August 2013.

INFOMAR 2013 - CELTIC VOYAGER MAPPING SOUTHERN PRIORITY AREAS AND BAYS

INFOMAR Survey CV13_01

Monday 22^nd April saw the commencement of the first RV Celtic Voyager INFOMAR survey leg of 2013, named CV13_01. Operations commenced off the Cork coast between Ballycotton and Youghal, shoreward of coverage attained in previous years.  The area forms part of the South Priority Area (SPA), stretching from Mizen Head in the south-west to Carnsore Point in the north-east.  The Priority Bays of Youghal and Dungarvan were also partially surveyed. Figure 1 shows the extent of multibeam coverage achieved in the area while figures 2, 3 and 4 show detailed seabed morphologies of the bays of Ballycotton, Dungarvan and Youghal respectively.   

Figure 1: Multibeam inshore survey coverage between Ballycotton and Dungarvan.

 

Figure 2: Seabed geomorphology offshore Ballycotton.

 

 Figure 3: Seabed geomorphology offshore Dungarvan.

 

Figure 4: Seabed geomorphology offshore Youghal.

Survey operations alternated between the inshore area above and an offshore block south of Waterford, shown in figure 5. The offshore survey block covers an area of approximately 320 km². Water depths range from 50 m to 80 m approximately with depths increasing from north to south. The seabed is mostly covered by sediment but outcropping rocks are also found in the north.

Figure 5: Offshore survey block south of Waterford.

An area east of Wexford and west of the Blackwater Bank was also mapped during a period of strong westerly winds. The multibeam shaded relief image in figure 6 shows that the seabed is largely composed of sediment waves. Water depths vary from 10 to 25 m approximately.

Figure 6: Multibeam image near Blackwater Bank Wexford.

Survey operations moved west for the final week of survey. The area included the waters around Old Head of Kinsale and Courtmacsherry Bay (figure 7). Its offshore extent was along the SPA boundary, more than 12 km offshore of the Old Head of Kinsale. Water depths ranged from 12 m to 100 m approximately. The extent of the mapped area was approximately 400 km². Several magnetic anomalies were observed, attributed to the geology. Survey operations finished on 31^st May. The Celtic Voyager remained operational for over 70% of the total time.

Figure 7: Multibeam image of Courtmacsherry Bay and Offshore Kinsale.

Wrecks

A total of 21 wrecks were mapped during this leg. Figure 8 shows an image of a wreck off the Waterford coast. The wrecks were initially identified from the main survey lines and then mapped in detail using a standard box in process of three parallel lines and one perpendicular line with multibeam water column data and magnetometer data acquired on each line.

 

Figure 8: Multibeam image of mapped wreck.

Groundtruthing stations

In total 128 groundtruthing stations were visited. A total of 111 samples were acquired from these stations, with no returns at 17. A Shipek grab was used throughout. Each sample was photographed and described. Samples varied from mud through to gravel. Figure 9 shows a photograph of the sample obtained at station 4.

Figure 9: Shipek Grab sample photograph.

Figure 10 is a distribution plot of the visited groundtruthing stations. Each red X marks a station.

Figure 10: Groundtruthing spatial distribution plot.

Sub Bottom Profiler Data

Sub bottom profiler data was acquired on each survey line. Figure 11 below shows an example of sub bottom profiler data with a palaeochannel in the view. Each horizontal red line represents 8 metres depth. The vertical blue lines are approximately 120 metres apart. The horizontal line near the top of the image represents the seabed return.

Figure 11: Sub-Bottom-Profiler data example.

 

 

 

View new data on Infomar Image Webmapping Site

New data is now available on the Infomar Image Webmapping site and in the INFOMAR webmapping services from the following surveys:

Geo11_01 - Dun Laoghaire, Co. Dublin
KRY11_01 -  Waterford Harbour
Geo11_02 - Waterford Harbour
KRY12_02 – Bunmahon, Co. Waterford
CV11_MeshAtlantic - Kenmare Bay,  Kerry/Cork
CV12_SEAI_Clare - West of Clare
KRY11_03 -  Killard Point, Co. Clare
KRY11_03 – South of Achill Island, Co. Mayo
Geo11_04 - South of Achill Island, Co. Mayo

These are primarily near shore surveys and the location of these new surveys is shown in yellow in the map.

These surveys were carried out by the R.V. Keary, the R.V. Geo and the R.V. Celtic Voyager.  Data produced from these surveys include bathymetry grids, shaded relief and a backscatter images, tracklines and survey polygons.

This image shows bathymetry data from survey around Inishbofin, Inishshark and south of Achill Island.

This is a shaded relief image of bathymetry data collected in Kenmare Bay.

The survey of Kenmare Bay was carried out by the Mesh Atlantic project with support from the INFOMAR project in terms of personnel and equipment. The Mesh Atlantic partnership is compromised of IFREMER, IMA, DIREN Bretagne (France), Marine Institute (Ireland), AZTI, IEO (Spain), ICNB, INRB, Universities of Aveiro, Azores, Algarve (Portugal).

In addition there is also new data on the website for sediment samples.  This includes historical samples in Zone 3 and particle size analysis results for sediment samples taken in 2011 and 2012.

Please note:

• All of the image layers on this website are also available as WMS services which can be used in ESRI ArcGIS Desktop, ArcGIS Explorer online and other freely available mapping packages, see the Google kml and WMS Links page for details.

• It is possible to download data used in the site. Use the   button in the tool bar at the top right of the page to click and drag a box around an area of interest, the tool will open our IWDDS download site and you then select the type of data you are interested in downloading.

Please note also to improve performance some of these layers are cached locally onto your computer as you browse the website.  In order to see new data it is necessary to clear the local cache and reload the page.  To do this in:

• Internet Explorer: click Tools > Delete Browsing History >Check Temporary Internet Files and click Delete.

• Mozilla Firefox: click Tools > Clear Recent History > Check Cache and click Clear Now

• Google Chrome: in the Chrome menu select Tools > Clear browsing data > Check Cache and click Clear Browsing data 

Lambay Island Survey

From late April to May 2013, the M.V. Cosantóir Bradán and R.V. Geo carried out survey operations around Lambay Island and along the coast between Howth and Skerries, Co. Dublin. This seabed mapping was carried out on behalf of the National Parks and Wildlife Service (NPWS - http://www.npws.ie/), who requested the survey so they could delineate habitats in the area. Survey coverage was also extended beyond the NPWS requirements in order to expand INFOMAR national mapping coverage in the area.

 

The M.V. Cosantóir Bradán is the latest addition to the INFOMAR survey fleet and is operated by the Geological Survey of Ireland (GSI). A fisheries patrol vessel in a previous life, she is now outfitted with a multibeam sonar mapping system - http://www.fisheriesireland.ie/Press-releases/minister-commissions-an-cosantoir-bradan-in-her-new-role-as-a-seabed-survey-vessel-at-infomars-2012-annual-conference.html.
The transducers (these are the part of the system that send and receive the sonar pulses) are deployed by means of a bow-mounted hydraulic frame.

 

The R.V. Geo is also operated by the GSI and is a 7.5m RIB (Rigid Inflatable Boat). She is equipped with an interferometric sonar mapping system, which is manually deployed by means of a bow-mounted frame.

Note: data shown in images below is not yet finalised and may contain some errors.

Overall survey coverage by M.V. Cosantóir Bradán and R.V. Geo

Close-up of survey coverage around Lambay Island

M.V. Cosantóir Bradán (Crosshaven, 2012)

 

 

R.V. Geo (Killary Harbour, 2012)

 

 

 

Cork Harbour Survey - To Be Updated

INFOMAR SEAI SURVEY 2013

From mid-March through to the end of April, the R.V. Celtic Voyager was tasked with the mapping of the seabed off the West Clare coast.

Due to the ideal wave regime, favourable seabed morphology and proximal port facilities, this area has been identified as a suitable region for the future deployment of wave energy converters. Sustainable Energy Authority Ireland (SEAI) leads a project to help realise this potential.

The INFOMAR program is collaborating with SEAI to provide them with a detailed understanding of the seabed morphology and surficial geology over this extensive area. Considerations of these environmental factors are critical to the planning and development of such marine infrastructure.

Despite challenging conditions for the vessel’s crew and survey team due to prolonged adverse weather, good coverage was achieved close to the coast.

The image below shows the extent of the multibeam and geophysical data collected by INFOMAR in support of the SEAI initiative.



The acquired multibeam data show some spectacular structures in the siliclastic bedrock and a Namurian/ Carboniferous contact.