Welcome to the web site for Sediment and Solute Transport on Rivers and Margins (SSTORM) Research Group! Reide Corbett and J.P. Walsh from East Carolina University and the UNC Coastal Studies Institute lead the team.
Check out our research in/on wetlands, estuaries, barrier islands, shelves and groundwater.

Friday, May 21, 2010

Three Successful Tripod Recoveries! ...and before lunch

20 May 2010, Noon

Last January we deployed some equipment on the seafloor to measure ocean conditions over time. This is a critical part of our project, the mission of which is to understand how layers of sediment are deposited by storms and modified by subsequent processes (in case you aren’t familiar with or forgot what we’re doing). The technology we now have to examine oceanographic processes is truly amazing; for example, we can monitor variations in currents throughout the water column from impressively small, rugged sensors that sit near the sea bottom. We usually attach several different types to a metal frame and deploy this “tripod” to the ocean floor. Then, we return some time later (4 months in our case) and send a special sound to an acoustic device which releases a rope and float which comes to the surface. Now all of this probably sounds pretty simple in concept. But the reality of setting up these various, expensive instruments (most of them $3,000+), strapping them to frames, getting them off a moving ship, lowering them in a controlled fashion to the seabed and then finding them and picking them up months later is really not a easy process. Also, it is a bit nerve racking… for a few months. Yes, we have insurance on most of our equipment, and we certainly have back-up systems and plans, but nevertheless, the whole thing is a bit stressful. Obviously, some of our concern comes from the fact that the ocean is vast and dynamic, but one our greatest worries is the possibility of human interference with our systems. Even in remote waters of New Zealand, fishing is common. During our last deployment we saw several trawlers.

So, hopefully after writing all this, you can appreciate how we were all much relieved to see the tripod floats pop to the surface when released acoustically (although our the primary release on one of the tripods refused to deploy initially!)

Below are some pictures of the tripod recovery process. Notice the deck of the ship filled with the three tripods. We were forced to recover all of them in succession because of our limited ship time and the approach of a storm. We are very happy to successfully retrieved all three and have gone into the port of Gisborne to unload the tripods, download their data (hopefully the instruments worked!) and get them ready for redeployment.

Daniel, one of the ship’s crew, throws a grappling hook to grab the acoustically released tripod float and enable us to haul up the equipment.

Calm seas allow for a relatively easy recovery. Note the crowded deck with the other two tripods already onboard.

Rip Hale, a graduate student at the University of Washington, is happy to see the tripods back...so he might have some good data for his dissertation!

The Captain, Simon, checks out a tripod...and the baby spiny lobsters who have made it their home.

Dr. Andrea Ogston from UW, a queen of tripod work, surveys the tripods for damage. She's happy to see them on deck.

No comments:

Post a Comment