Members of the Sediment Dynamics Group are slowly arriving in Brazil for our fifth tidal Amazon River cruise. Yesterday along with our Brazilian collaborators we measured discharge at the town of Obidos, the farthest downstream gauging station on the Amazon. Today we will measure discharge on the Tapajos River, a major tributary that meets the Amazon at the city of Santarem. Tonight we meet the rest of our UW and Brazilian colleagues and continue our research farther downstream.
The group is well-represented at Ocean Sciences this week, with Andrea co-chairing the session on “Sediment Delivery, Transport, and Deposition in Aquatic Environments,” Dan and Rip giving talks on sediment transport in the Amazon tidal river and Waipaoa shelf (respectively), and Emily presenting a poster on Elwha sediment processes. Go Sed Group!
Dan: Monday, Feb. 24th, 10:30 am, room 312
“Tidal-channel flow and sediment transport in environments influenced by the tidal Amazon River, Brazil”
(Here’s a photo of Dan rocking his talk)
Rip: Tuesday, Feb. 25th, 8:30 am, room 312
“In-situ observations of wave-supported fluid mud on the continental shelf”
(And here’s the question portion of Rip’s awesome talk)
Emily: Tuesday, Feb. 25th, 5 — 6 pm, poster hall (#141, group P)
“Sediment dispersal and deposition on a submarine delta during dam removal: Elwha River, WA”
On Tuesday, February 18th at 7 pm, the UW’s Burke Museum will be hosting a series of brief (5 1/2 minute) presentations on Elwha Restoration science at the Neptune Theatre in the University District. The full program is available on the Burke Museum event page; topics include pre-dam archaeology, salmon colonization, fluvial geomorphology, and marine change. Emily will be presenting on sediment transport across the subaqueous delta.
This is offered in conjunction with an ongoing exhibit (Elwha: A River Reborn) at the Burke Museum, which runs through March 9th.
Tickets are $5 at the door.
Should be a fun event!
P.S. Love the UW newsletter photo of Aaron and Wenhua collecting mud! Short Takes Offers the Perfect Nerd-to-Speed Ratio
Andrea, Emily, and Steve Rubin (USGS)—with help from Ian Miller (WA Sea Grant)—made a successful rapid response cruise to the Elwha Delta, following a day of heavy rain. The goal was to collect surface water samples from the river plume. Given sufficiently high sediment concentrations, these samples will be usable for grain-size and concentration analyses.
Collecting these samples has been on the to-do list for a long time, but this winter has been particularly dry (= low river flow). The January 11th rainstorm did not flood the river, but still made for a pretty exciting day on the water and a truckload of great samples. Emily is currently processing these in the lab – sediment will be allowed to settle for about a week, and after a series of dilutions, will be processed using the Sedigraph. The goal is to determine size distributions of disaggregated particles in the plume.
Back to watching the weather for the next big one! With any luck, we’ll see a pineapple express (http://www.komonews.com/weather/faq/4307577.html) sweep through western Washington this winter.
Winter at the Elwha — this was the edge of the surface plume a day after heavy rains. Nice sediment samples!
An interesting mix of grain sizes in this bed sample
Samples! (Photo by Ian Miller)
As part of our ongoing study of sediment dispersal offshore of the Elwha River, we made two scheduled research cruises in late 2013 (August and November). The goal of both cruises was to service two seabed instrument systems (tripods) and survey the sediment plume, water column, and seabed across the subaqueous delta.
Instrument servicing was overall a success, though a couple unlucky instruments were returned to the shop rather than the ocean. We retrieved some nice data on advection of muds both during the summer dry season and a couple fall rainstorms. One of the photos shows Dan Nowacki and Niall Twomey hard at work in our favorite workspace, the Port Angeles harbor. Hooray for no rain in both August and November!
The ship-based surveys were also successful. In November we made our first Kasten coring attempt since the project began. The most successful site yielded about 40 cm of mud, which represents a huge change from the gravelly substrate seen on many other cruises. A new sandy/muddy deposit is growing outward from the river mouth into Freshwater Bay, while other parts of the delta remain coarse (gravel, sand and the occasional boulder).
The cruises were made possible by help from our dedicated lab crew, including Andrea, Chuck, Emily, Dan, Rip, Aaron, Katie, visiting international students Suzan and Wenhua (their first cruises in Washington State!), Kevin, Julia, and Niall, and also Nicole Harris from Western Washington University (who researches Elwha nearshore changes)—and of course the great crew on the R/V Barnes (Ray, Greg, and Bob). Looking forward to another great cruise in April!
We caught barnacle season during the summer deployment. Lots of scrubbing happened immediately after this photos as taken.
Dan and Niall work on both tripods at the Port Angeles harbor in August
Niall and Suzan set the Shipek to collect a seabed sample
Many portions of the subaqueous sample are still too coarse to sample with the Shipek. That doesn’t mean they always come back empty, though…
New muddy/sandy deposits near the river mouth
At the end of the August cruise, the secondary tripod was returned to its 22-m site offshore of the river mouth
Andrea & Aaron monitor the progress of the sidescan sonar system
Kevin and Wenhua collect surface water samples in November
We are currently accepting applications for a 10-week (March 31 — June 6, 2014), 15-credit, undergraduate research apprenticeship, at the University of Washington’s Friday Harbor Labs in the San Juan Islands, WA. This research apprenticeship focuses on the impacts of dams on the marine sedimentary system and the impacts of the release of reservoir-trapped sediment into the marine environment during dam deconstruction. Dam removal projects are becoming an attractive means of restoration for depleted fisheries, river ecosystems, and coastlines, but we do not yet understand the full range of effects our “restoration” will have.
With help from mentors, students will design and complete individual research projects using data they collect at the Elwha River delta; as part of a larger, NSF-funded research project. Research work will be complemented by lectures, guest presentations, and weekly field trips to a variety of nearby sedimentary environments. Through this classroom and experiential learning, students learn about the range of sedimentary processes that occur near river mouths, human impacts on coastlines, interactions between biology and sediment, and regional geology. The apprentices to be recruited for this course will have the potential to become informed scientists and managers in charge of decision-making in future restoration projects.
Please direct questions to Dr. Andrea Ogston. Additional details are available here.
Fall 2013 was an exciting time for the Sediment Dynamics lab group!
Kristen Lee Webster gave her final presentation for the PhD, and turned in her dissertation, “Sediment dispersal and accumulation in an insular sea: deltas of Puget Sound”. Congratulations, Kristen, on this impressive accomplishment!
Andrea, Kristen, and Chuck celebrate after Kristen’s PhD defense
In addition, Aaron, Emily & Katie deserve a big round of congratulations:
Aaron Fricke defended his dissertation proposal and passed his general exam.
Emily Eidam presented her MS project on the Elwha dam removal project, and was approved to move on to the PhD program.
Katie Boldt won an AGU Outstanding Student Paper Award for her presentation at Fall AGU in San Francisco.
Members of the Sediment Dynamics Group recently returned from a three-week stint in Brazil, where we completed fieldwork on the Amazon River and its associated sedimentary environments.
Our first field site was along the Amapá coastline north of the mouth of the Amazon River. The mangroves that flank the coast here are bathed in Amazon River sediment that is transported northward after exiting the mouth. We undertook a pilot study along the Rio Calçoene, downstream of the town of Calçoene.
View Map on Google Maps
Near Calçoene, the river has relatively little suspended sediment, and the water appears quite clear.
Rio Calcoene near Calcoene
Closer to the mouth, suspended sediment concentrations are much higher, and the river starts to resemble chocolate milk. Almost all of this sediment is likely from the Amazon River, the mouth of which is some 250 km to the south.
Near the mouth of the Rio Calcoene
In addition to making measurements and collecting samples along the river itself, we did work in a few small channels that incise the mangrove forests that characterize this part of the Brazilian coastline.
A small channel at low tide incising mangrove forest
A closeup of a channel at low tide
The UW’s R/V Clifford A. Barnes recently completed its 1000th research cruise, as described in this UW Today article. Our group has used the Barnes extensively over the past few years as part of our project on sediment impacts related to the Elwha dam removal. Be sure to check the photo gallery on the UW Today article for a shot of our own Kristen Webster on a Barnes cruise in 2009!
Wow–what a whirlwind. The second half of our fieldwork was a frenzy of activity. We finished the second 25-hour transect and completed the third quickly and efficiently. With over 75 hours of continuous ADCP measurements (3, 25-hour station occupations), 230-plus CTD (conductivity-temperature-depth) casts, over 100 sediment samples, and about 150 water samples, we have a lot of data on our hands waiting to be analyzed. Right now we’re in Seoul airport waiting for our flight back to Seattle. Look for another post or two with some more great photos and perhaps a few data plots describing what exactly it is we did on the river. For now, we’re headed to our gate, so here a few photos.
A night view from the bow of Aaron filtering
Rip doing creating a manual vacuum while we repaired our vacuum pump
- Sunrise on the Mekong