Brief description
Torres Strait is one of Australia's most important seaways in terms of shipping and defence. It forms Australia's only true international boundary. It is a shipping focal area and major seaway for Australian and foreign merchant vessels. This is the first report, in a series of four (four cruises represented in image), outlining the results of investigations into sandwave movement, currents and sedimentation in the main shipping channels of Torres Strait.Lineage
Statement: The current meter was anchored on the seabed using a weighted tripod in which the rotor was located 100cm above the bed it measured flow speed and direction each 10 minutes. Upon recovery, it was discovered that the current meter was still recording data but that it had been damaged; its rotor and vane assembly were missing. Furthermore, the tripod had been broken and did not appear to be holding the meter in an upright position (ie. with the rotor 100 cm above the bed).In the laboratory, the current meter data were read into the computer. A total of 1,147 useful observations were obtained (approximately 8 days of data) before current speed observations were no longer recorded.
A total of 65 comparisons of sandwave position were made along 20 parallel survey tracks located +/- 5m apart. Precision in positioning ensured that no along-crest variation in sandwave location or shape would bias the data. Survey track lines were aligned from 90 degrees to 70 degrees to the trend of sandwave crests as determined from side-scan sonar records.
Navigation for the survey was by Miniranger system.
Cores were obtained using a piston corer.
The currents were measured using an Aanderaa RCN-4 self recording current meter.
The temperature/salinity measurements were made with a Yeokal CTD.
Notes
CreditSchneider, P.M.
University of Sydney
Materials Research Laboratory, Defence Science and Technology Organisation
The aims of the project are: 1. To map the distribution of mobile bedforms (sandwaves/sand banks) and locations of sediment accumulation (thickness above bedrock) versus areas of scour in Torres Strait. 2. To identify the sediment's physical properties and assess them with respect to burial upon impact of objects. 3. To quantify current strengths along shipping channels. 4. On basis of the above, to quantify sediment transport and sedimentation (vertical accretion) rates in and adjacent to the shipping channels of Torres Strait.
Issued: 09 07 2007
Data time period: 1988-02-15 to 1988-03-17
text: westlimit=141.5; southlimit=-10.5; eastlimit=144.5; northlimit=-8.5
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