Belgica Cruise Report 2007/19

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1 Belgica Cruise Report 2007/19 Jan Haelters, Alain Norro & Koen Degrendele. Geology: 10/09/ /09/ Cruise details 2. Participants 3. Scientific Objectives 4. Operational course 5. Results 6. Remarks 1

2 1. Cruise Details Vessel: RV A962 BELGICA Cruise number: Date/Time: Zeebrugge 10/09, departure postponed until 11/09 Zeebrugge 11/09, 10h30 departure Zeebrugge 14/09, 11h30 arrival Area: Belgian Continental Shelf - Dutch Continental Shelf Chief Scientist: Koen Degrendele Participating institutes: FPS Economy, MUMM 2. Participants NAME Institute 10-14/09/2007 Koen DEGRENDELE FPS Economy X Marc ROCHE FPS Economy X Patrik Schotte FPS Economy X Alain NORRO KBIN - MUMM X Roger KNUTS KBIN - MUMM X Alain SIMON KBIN - MUMM X Jan HAELTERS KBIN - MUMM X Robin Brabant KBIN - MUMM X Total number of participants 8 Econ-MR 3. Scientific Objectives Implementation of the continuous investigation laid down in section 3, 2, subsection 3, of the law of June 13th 1969, concerning the exploration and exploitation of non living resources on the Belgian Continental Shelf, and the concession decisions. The follow up of the repercussions of the sand extraction on the stability of the sand banks en surrounding area in the exploitation zones, in order to formulate policies concerning the exploitation in the concession zones on a scientific base. The sediments of the Belgian continental shelf will be investigated in order to: 1. Establish the impact of sand extraction on the sand budget and seabed sediments. 2. Survey the sand winning sites to detect significant changes of the seabed sediments and the morphology of the seabed and sand banks in order to guarantee the availability of sand to extract in the future. 3. Establish a correlation between acoustic images and bottom sampling and video transects. Continuation of wreck surveying to calibrate the multibeam system. In addition, a simultaneous multibeam survey with several Belgian and Dutch hydrographic vessels is planned during this week. The results of this survey can provide important information on the quality of the multibeam measurements on board the Belgica. MUMM-AN The aim of this cruises was to take data permitting the calibration, using underwater images, of the retrodiffused accoustic signal taken from multibeam echosounder. Georeferenced 2

3 underwater images and short movies are taken on already multibeam mapped zone on the Hinderbank region and new zones on the Bligh Bank. Additional in-situ measurement of sand thickness will complete the information. Environmental impact assessment of the wind farms for which a building permit has been requested (MEB): 1) Blighbank 2) Bank zonder naam (between Thorntonbank and Blighbank) There are uncertainties about the current composition of the substrate of the banks, the slopes and the gullies between the banks. Therefore in the framework of the MEB it would be useful to have an indication of this substrate composition. It is expected that the substrate of the bank will be affected/altered due to the construction of the wind turbines, which is foreseen in However, the impact assessment needs to be done during the coming months. In this framework the objective is the sampling of the substrate composition (cobbles, coarse sand?) of the Blighbank and Bank zonder naam, especially in the shallowest parts on the bank and in the immediate vicinity. Different methodologies should be used: 1) Diving: Scientific divers should take photograph and short movies at selected locations. The divers tow a GPS buoy and in-situ measure sand thickness. The divers will also sample some rocks. 2) Van Veen samples should be taken at each station, followed by Hamon grab 3) If possible and feasible within the sand and gravel project: multibeam image to be calibrated by the results of the dives. For assisting with the labeling, fixing and storing of samples, a section 15 assistant will be on board (Jan Haelters). If feasible (depending on meteorological conditions), live organisms will be photographed in an aquarium to be put on board. 3

4 4. Operational Course Local time (GMT+2) The departure of the Belgica was delayed until Tuesday due to bad weather conditions. Tuesday 11 th September 10:30: Departure and transit to the Flemish Banks. 14:00: Briefing of the divers 'wet lab' presence of COM Belgica and Bootsman. 17:00-22:00: Multibeam calibration on the diving area RZ2. 23:10: Start multibeam surveying on the reference area s KBMA, KBMB and R2. Wednesday 12 th September 10:00: End multibeam surveying. Transit to diving spot BB1 (Blighbank). 12:00: Sampling with Hamon grab at stations BB1. Marking of the diving spots by the crew and verification of position and current velocity. Diving on spot BB1 at 13:00 and BB2 at 18:00. 14:30-17:30: Sampling with Hamon grab at stations BB2, BB3, BZ1, BZ2, BZ3, BB6 and BB5. 19:20: Sampling with Hamon grab at station BB4. 19:50-21:00: Multibeam survey on the diving area. 21:30-22:30: Multibeam heading calibration on unknown wreck. 23:00: Surveying along decca-lines across the Thorntonbank. Thursday 13 th September 09:40: End multibeam surveying on the Thorntonbank. Transit to diving spot KG1 (Kwintebank). 11:00: Multibeam survey on the diving areas KG1 and KG2. 11:30: Marking of the diving spots by the crew and verification of position and current velocity. Diving on spot KG2 at 12:30. 13:30: End of diving on spot KG2. Due to the bad underwater visibility the diving on zone KG1 is cancelled. An alternative diving spot near the Oosthinder is defined. 13:30-16:00: Transit to diving spot near the Oosthinder. 16:00-16:30: Sampling with Hamon grab on the diving spot. 16:30-18:00: Multibeam survey on the diving area. 18:00: Marking of the diving spots by the crew and verification of position and current velocity. Diving on spot at 19:30. 20:40-21:30: Multibeam survey on the diving area. 21:30: Transit to the Middelkerkebank 23:40: Multibeam survey of zone R2. Friday 14 th September 03:30: End multibeam surveying. Transit to Vlissingen for simultaneous multibeam survey. 07:30-09:45: Simultaneous multibeam survey near Vlissingen. 09:45: End multibeam surveying. Transit to Zeebrugge. 11:30 End of cruise 2007/19, disembarkation of all equipment and scientists 4

5 5. Results Econ-MR 1. Multibeam survey of the KBMA, KBMB and R2 monitoring areas: 5

6 6

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8 2. Multibeam survey of the decca-lines across the Thorntonbank: 8

9 3. Multibeam survey near the Oosthinder (diving spot): 9

10 4. Multibeam survey near Vlissingen: 10

11 MUMM-AN MUMM Scientific diving Wednesday 12 September 2007 Air test realized on compressor PFU205 with a Drager simultan HP gave result for CO2, CO and Oil (Shell Corena) less than DIN3188, Water vapor was limit for the DIN3188 at 50 mg by cubic m. Time in UT for camera, GPS and diver. First dive on zone BB N; 2 45E WGS84 Team Norro and Simon with Knuts in safety. 13:21(ut+2) in water 38 m for 15 min bottom time and 5 min at 5 m safety stop. Out of the water at 13:50 (ut+2) Norro on CCR and on Simon OC, EAN 31. Sand thickness measurements: Time Sand thickness in cm 25 min min min min min min Table 1: Sand thickness measurements along BB1 track Navigated GPS track, underwater photography and short video have been taken. Few rocks have been taken by hand in plastic bags Photo 1 Stick used for sand thickness measurements 11

12 Second dive at BB N; 2 47 E Team Norro and Simon with Knuts in safety. 18:00(ut+2) in water 20 m for 31 min bottom time and 5 min at 5 m safety stop. Out of the water at 18:40 (ut+2). Norro on CCR and Simon with OC; EAN30 Time Sand Thickness in cm 05min min min min min min min min min min min min min min min min min min min min15 20 GPS track and photo/short video have been taken Thursday 14 September 2007 First dive on KG2 (see fig 1) Table 2: Sand thickness measurements along BB2 track 12

13 Fig 1 KG2 site between between Kwintebank and Buiten Ratel Team Norro-Simon and Knuts in surface safety In water at 12:45 for 2 min at 27m depth out of the water at 12:50 The dive was aborted due to very bad water visibility encountered at the bottom Norro with CCR and Simon OC; EAN30 Second dive on site: 51 39,658N; 2 38,211 E (WGS84) Due to the bad visibility close to the shore it was not possible to continue on the planned dive sites. It has been decided to move to a location North of the traffic line. The track of the dive is presented at fig 2. Diving team Norro-Simon and Knuts in surface safety. Start of the dive at 19:50 (UT+2) for 10 min bottom time at 48m, 9 min at 6m. Out of the water at 20:15. Norro with CCR and Simon with OC; EAN 28. Navigated track and underwater photo have been taken. 13

14 Fig 2. DTM and track (white line) of the 14 September second dive The red dot at the center of the image is the location of a Hamon grap taken during the cruise. 14

15 MUMM Sectie 15 Doel was meer gegevens te bekomen over de sedimentsamenstelling (en mogelijk ook over ecologische data) in een aantal punten op de Blighbank en de bank zonder naam, en in de diepere geulen. Er is een aanvraag om op de Blighbank windturbines te plaatsen, en een gelijkaardige aanvraag wordt verwacht voor de bank zonder naam (tussen de Blighbank en de Thorntonbank). Tijdens de constructie van die windparken zal vermoedelijk een grote hoeveelheid sediment verplaatst worden, en een (tenminste tijdelijke) impact op de bodemsamenstelling en de bodemorganismen, mogelijk ook in de geulen rond de banken, kan verwacht worden. Alle voorziene staalnames konden uitgevoerd worden op 12 september Er werden geen Van Veen stalen genomen gezien de goede weersomstandigheden en de uitstekende werking van de Hamon grab. Het is duidelijk dat de Hamon grab, ook met de assistentie van de bemanning, enkel bij relatief goede weersomstandigheden kan ingezet worden. Op 2 stations werd een duik uitgevoerd door het team van A. Norro. Bij de eerste duik, op het station BB1, werden enkele stenen naar boven gebracht (3 stenen, de grootste met een gewicht van ongeveer 2 kg). Opvallend was dat die stenen, in tegenstelling tot stenen in het Westhinder gebied, vrijwel niet begroeid zijn met macroscopische organismen. Mogelijk is dit een indicatie van een intensieve verstoring (boomkorvisserij, dynamiek van het gebied?), of wordt dit veroorzaakt door de aanwezigheid van slib. Tijdens de duik op station BB2 werd door de duikers een zandbodem, met zandduinen waargenomen, zonder stenen. Opvallend was een locatie met veel zandspiering Ammodytes sp.. Tijdens de duiken werden foto s genomen. Tussen de staalnames werden door BMM Sectie 15 enkele aquaria opgesteld met tot doel organismen te fotograferen. De ervaring hiermee was dat dit goede mogelijkheden bood om bepaalde soorten levend te fotograferen, wat nuttig kan blijken voor identificatiedoeleinden, maar dat tevens uitstekende weersomstandigheden noodzakelijk zijn voor de technische opstelling en een goed resultaat. Staalnames op 12 september 2007 (alle met Hamon grab) Alle voorziene staalnames (inclusief de reservepunten) werden uitgevoerd. Er was een kalme zee, bij 2 Bft wind. Van het sediment werd onmiddellijk na de staalname een foto genomen. Een substaal van ongeveer 0.5 liter werd genomen, en gefixeerd met formol voor analyse van de korrelgrootte. Daarnaast werden op zicht reeds een aantal organismen verzameld, en eveneens gefixeerd in formol. Tijdstip Station Positie N Positie E Diepte (m) (lokale tijd) (Furuno) 11:59 BB :39 BB :06 BB :35 BZ :00 BZ :19 BZ :00 BB :23 BB :26 BB De stalen genomen waren overwegend zand. Enkel op station BB1 bevonden zich keien (2 tot 10cm diameter) in het zand. Slib was aanwezig in de stalen genomen in stations BB1 en BB4. 15

16 Staalnames op 13 september Op 13 september werden op een bijkomend station twee Hamon grab stalen genomen. In het eerste van deze stalen bevonden zich veel keien. De stalen werden in zijn geheel verzameld voor verder onderzoek. Tijdstip Station Positie N Positie E Diepte (m) (lokale tijd) (Furuno) 16:12 D N E :20 D N E

17 6. Remarks The crew and the commander of the Belgica are greatly acknowledged for their cooperation. Econ-MR During the calibration a problem with the multibeam data, which was communicated after cruise , was witnessed. Apparently a time delay problem occurs when "Datagram" is chosen as the "Time to use" in the installation menu. It seems that the datagrams provided by the GPS are unstable. The problem was easily solved by selecting "System" instead of "Datagram" in Time to use", as shown on the screenshot of the input parameters of the cruise. Because we use PPS we can use the system clock without any problem. With the PPS unit, the GPS and system clocks are synchronized. MUMM-AN Due to the bad underwater visibility the diving on zone KG2 on Thursday had little to no result, hence the diving on zone KG1 was cancelled. The use of the Secchi disk to measure the underwater visibility could be an important tool during the operations before the actual diving takes place. 17