The Sediment Dynamics Group is wrapping up its monitoring program at the Elwha River. During dam removal in 2011-2014 we monitored the transported sediment through the coastal area. For the past two years, we have deployed instruments on the seabed to monitor sediment transport and light availability. Now those instrument platforms are going into storage and the instruments are going to new projects. During instrument deployment cruises on the RV Barnes and the USGS owned Frontier. We collected sediment samples to track the progression of the new deposit in Fresh Water Bay.
Emily Eidam and Hannah Glover carrying a boxcore (Photo credit: Mark D. Stone).
We also collected water samples to look at the composition of suspended material. This sample processing is also wrapped up, and we’re entering a new phase of data analysis. The data will provide insights into how the dam removal impacted the habitat on the seabed. Light availability is especially important for kelp, which provide habitat for other organisms. These results will be valuable for reducing environmental damage during other dam removal projects.
This quarter, Andrea Ogston, Ian Miller, and Emily Eidam are working with nine undergraduate research apprentices at Friday Harbor Labs to study the effects of the Elwha River Restoration and dam removals on coastal sedimentary processes and habitats. This work is part of Ocean 492: Marine Sedimentary Processes Research Apprenticeship, a 15-credit class that provides students across majors and across universities an opportunity to learn hands-on research techniques, data processing tools, and writing skills.
We took advantage of a stormy day to watch waves at the outer Washington coast during the field week
Lauren and Mary work to refurbish light sensor systems on the deck of the R/V Barnes in October
This year’s apprentices are tackling a wide variety of projects ranging from light availability to wave processes to benthic and planktonic abundances. After an action-packed field week in mid-October on the R/V Barnes and a follow-up trip on the R/V Centennial, we have been busy processing samples and crunching numbers in the lab. Final presentations (and maybe a dock jump!) will take place in mid-December.
We visited former Lake Aldwell to wander through the remnants of last century’s forest and the saplings of the last five years’ recovery
Morning exploring at the Skagit Delta
If you’re interested in Ocean 492: Marine Sedimentary Processes, visit the FHL courses page or contact Andrea (see People page).
What a soggy winter in the northwest! The maps below were generated from the National Weather Service’s AHPS (Advanced Hydrologic Prediction Service). The first shows shows national rainfall totals for the past 60 days. More than 30-50” of rain have fallen in the the Olympics, which is above normal (see second map).
What does this mean for the Elwha River? Some pretty big flow events. Below is a graph generated from the USGS NWIS (National Water Information System) for station 12045500 at McDonald Bridge, 8.6 miles upriver of the coast. This shows the river hydrograph, or water discharge record, since Sept 14, 2011, the approximate start date of dam deconstruction. This winter’s events are the biggest since 2011 – note that the left axis is a log scale, making this year’s flows even more impressive.
When rainstorms bring these increases in river discharge, more sediment is exported from the former reservoirs. In response to this winter’s active storm season, we teamed up with Ian Miller at WA Sea Grant (see his Coast Nerd Gazette) and Dave Thoreson from UW Oceanography Tech Services to deploy a small instrument package offshore of the river mouth. We caught a break between storms on Dec 4, 2015 and launched the “mini tripod” in Freshwater Bay, complete with upward- and downward-looking acoustic doppler current profilers (ADCPs), a temperature/salinity/turbidity/wave sensor, an optical backscatter sensor (OBS), a light sensor, a “sedimeter” (32 OBSs on a stick), and a couple of sediment tube traps. Here’s a photo of the system ready for deployment from the R/V Wealander, with Dave at the helm and Ian helping the launch:
We also collected water-column profiles using a conductivity/temperature/depth (CTD) sensor with optical backscatter sensor (OBS), as well as a laser particle sizer (a LISST). With these measurements, we can look at the structure of the muddy, freshwater “plume” created by the river water flowing on top of the more saline ocean water. By analyzing the structure of this muddy, freshwater lens, we can better understand where the mud is going when it floats out to sea. Below, Ian prepares to deploy the LISST while Dave drives and Andrea collects water samples. The Wealander was a great platform for our rapid sampling!
The instrument package will remain on the seabed and collect data every hour until we retrieve it in February…fingers crossed for another good weather window!
Just a quick update from the field –
Week 1 of Mekong field work went well; after planning meetings, the channel group (UW + Tulane + VNU) started multibeam and water column surveys, the mangrove group (UW + U. of Waikato + WSU + Boston U + VNU) began instrument deployments, and the shelf group (UW + NSCU + IMGG) loaded the boat & departed from Saigon.
Dan C. spent the end of August in Saigon organizing logistics for the September field work. The scientific equipment has arrived, and we are excited to start in the field in a couple weeks. Here’s a view of the Saigon River from downtown Saigon (Ho Chi Minh City), about 130 km northwest of our study site on the tidal Mekong River:
August 17-21 saw the completion of another successful Elwha cruise. After an exciting (i.e. rainy!) March, the summer was relatively quiet in terms of river discharge. The primary goal of the cruise was to remove, refurbish, and re-deploy the primary seabed instrument system, which we did in record time (36 hours!) after an initial failure of one of the release mechanisms (thanks APL for loaning us a backup control unit!). Meanwhile, ship-based survey efforts focused on collecting grab samples from the Freshwater Bay deposit to track any changes in extent throughout the summer. On the final day of the cruise, we also recovered 6 box cores from Freshwater Bay, which will be x-rayed, analyzed for grain size, and measured for radioisotopes in the lab.
Many thanks to everyone who helped make this a successful cruise! Bob and Todd of the Barnes, Aaron, Dan N., Wenhua, Julia, and Brianna from our lab group, Maggie McKeon from UW Civil Engineering, Bethany Nagid from UCSC, and Jacob Melly from Peninsula College provided invaluable assistance and no shortage of positive, creative thinking. We also enjoyed hosting guests from UW Advancement and the Seattle community on the box coring & and re-deployment portion of the cruise, and appreciated the opportunity to share the exciting research happening at the Elwha.
Dan Culling, Research Scientist joined the lab in March, and spent an intensive spring and summer coordinating field logistics for upcoming Mekong Delta field work. Together with Aaron and Emily, Dan organized and packed a 20’ container, which arrived in Ho Chi Minh City in late August. The field work, due to start in September, will focus on sediment-transport process and deposits in the tidal river, mangroves, and continental shelf. This work is an exciting collaboration between UW, Vietnam National University, VAST Institute of Marine Geology & Geophysics (Vietnam), NC State University, Washington State University, Tulane University, Boston University, University of Waikato (NZ), University of Miami, and UNSECO-IHE.
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.
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