Category Archives: Blog

Hot off the press

Check out our brand new publication in the Journal of Geophysical Research: Earth Surface about sediment dynamics in the Ayeyarwardy Delta!

Glover, H. E., Ogston, A. S., Fricke, A. T., Nittrouer, C. A., Aung, C., Naing, T., et al. (2021). Connecting sediment retention to distributary channel hydrodynamics and sediment dynamics in a tide-dominated delta: The Ayeyarwady Delta, Myanmar. Journal of Geophysical Research: Earth Surface, 126, e2020JF005882. https://doi.org/10.1029/2020JF005882

And please get in touch if you can’t access the article and would like to read it (hglover@uw.edu).

Sampling along the Bogale River in Sept 2017

Fifteenth Century Floods!

The Sediment Dynamics Group recently returned from a short field mission to the lower reaches of the Columbia River, supporting UW scientists who are searching for and sampling two unknown strata that were emplaced during the fifteenth century. These sedimentary layers are being studied by a paleoseismology research group at UW who aim to piece together the character and precise timing of three geologic events: 1) the Bridge of the Gods dam breach, 2) the eruption of Mount St. Helens, and 3) the T2 subduction zone earthquake. The timing of these events relative to one another is very close, but scientists continue to grapple with the details of their potentially interrelated history, and advances in this realm could yield insights into how our landscape will rapidly change during the next subduction zone earthquake.

Surveying equipment on Wallace Island.

The two key stratigraphic layers in this study are 1) a coarse-silt floodplain deposit emplaced by a flood resulting from the Bridge of the Gods land-bridge failure, and 2) a tephra layer emplaced by a water-rafted debris from a volcanic eruption, likely Mount St. Helens. Field methods included outcrop interpretations (contact analysis, identification of cross-bedding, elevation, etc.), grain size analysis, core C14 geochronology, and core CT scanning. The extent of this deposit has been mapped for >30 km, from Clatskanie to beyond Svensen OR. The canoe is the vehicle of choice for this fieldwork, allowing easy access to the muddy river cutbanks which contain the event layers. This is also “one of those sites” where you’ll be caught in the rising tide if you don’t work quickly (see below)!

All smiles as the tide catches up with us. Only a few samples to go!

 

MSP Is Back!

Rainbow over the Elwha! (Photo credit: C. Williams)

The Marine Sedimentary Processes Research Apprenticeship headed back to the Elwha River last week. In this class, students develop their own research questions related to the Elwha dam removal project, collect data, and write a thesis paper all in one quarter! Phew! This year students are focusing on the interactions between sediment transport and biological communities in the coastal area close to the river. We have the opportunity now, 5 years after dam removal, to now examine the system as it approaches a new equilibrium.

We went on two separate research cruises with 4 students each time (for COVID safety) on the School of Oceanography’s R/V Rachel Carson. The first cruise had spectacularly great weather. Students collected benthic grab samples, CTD profiles of the water column, and collected box cores. The second cruise was a bit choppier! We hit some large waves and had to adapt our sampling plan rapidly. But the students still hung in there and collected amazing data. We even managed to sneak in a quick box core despite the weather.

Over the next few weeks we will focus on processing all this data and analyzing the results. Stay tuned to hear more about the class and their results this fall.

Max and Hannah deploying the shipek (they’re smiling under those masks!)

Pod Dam weathering the rough seas with a smile!

Hannah is sad that the shipek failed to collect a sample

Max, Chris, and Hannah (from Pod Baddies) prep instruments for deployment

Alex recovering the Shipek

Ocean Sciences Meeting 2020 (+ sunshine)

This week the Sed Lab has been in sunny San Diego at the 2020 Ocean Sciences Meeting. Conferences are a great opportunity to share research, hear fresh ideas, and learn about new opportunities. Evan and Andrea presented early results from Astoria Canyon. Robin presented posters for both her education research and the final chapter of her PhD (!!!), which examines particle aggregation and deposition in the Mekong River. Hannah gave two oral presentations, one on building a global scientific community and one on sediment dynamics in the Ayeyarwady River Delta.

Robin presenting her poster

Andrea’s presentation

Conferences are also a wonderful chance to catch up with old friends and make new friends. We hung out with Rip, Dan, and Emily, and heard about their latest research. And, most importantly, we also got a good dose of sunshine after a long PNW winter.

Evan and Rip discussing Astoria Canyon

Hannah’s presentation

Back to Myanmar

This past week the Sediment Dynamics Group was back in Myanmar! Andrea and I presented results at the International Joint Symposium at Pathein University. The focus of the symposium was “Challenges in educational development on agricultural and food resources in tropical Asia”. It was very different from the usual presentations we see! There were lots of talks about rice farming and fishing. But we met up with some old friends and made some new ones too. It’s always exciting to connect with researchers from other countries.

After the symposium we met up with Aaron and Evan, and headed back to Meinmahla Island to collect some new data. For the past 2-3 years, we’ve been investigating sedimentary processes in different types of tidal channels in the island. The island is a mangrove preserve, so we’re able to study processes in a natural environment. There are also agricultural fields along the banks of the river near the island, so we can investigate processes in a modified landscape. It’s an ideal study site! There are also lots of crocodiles, snakes, and centipedes (oh my!).

Even though it’s the rainy season we had amazing weather, and there was only one downpour. We measured water and sediment flow in the tidal channels and surveyed the island. We collected lots of videos of the river banks so that we can understand how the bank shapes change through the island. We also measured the elevation of the island and agricultural fields. It was a long week of hot work, but we got some awesome data!

CERMIT the tripod returns!

This May, the UW Sediment Dynamics Lab deployed a benthic tripod in the head of Astoria Canyon to measure canyon hydrodynamics and sediment flux. Over the summer, our tripod recorded minute-by-minute data, documenting the forces that move sediment through Astoria Canyon and into the deep water sediment record. This fall, it was time to recover our tripod from the seafloor. Andrea and Evan boarded the RV Rachel Carson, steamed out to the deployment site, and sent our tripod a signal to release its recovery float… After sleepless nights worrying about bottom-trawl fishing nets hauling away our tripod, we were relieved to discover it was intact and upright, just where we left it. Recovery went smoothly in low seas, and within the hour, our tripod was on deck. We spent a few hours cleaning sandy mud off its feet, scrubbing “biology” off of its sensors, and downloaded data from its instruments.

CERMIT the tripod, above water for the first time in four months.

This little crab was recovered with our tripod.

Although the tripod was safely on deck, our jobs were far from over–we had also set out to collect seismic profiles and sediment cores from the canyon! The USGS accompanied us aboard the RV Carson, and in collaboration with this project, they created a survey plan to map the geologic structure of Astoria canyon with seismic gear (CHIRP and multichannel). Together, the crew logged ten days of 24-hour seismic data collection, and through all that surveying, we managed to have some fun. We caught salmon and tuna, saw dozens of humpback and pilot whales, and had heated discussions over the best practices in coffee brewing. After returning to port, the USGS crew returned to Santa Cruz, reinforcements from UW’s Sed Lab arrived, and we boarded the vessel yet again for two final days of coring. Over this two day effort, the sediment lab collected 25 box cores in and around the canyon head and shelf rim, coring efficiently in spite of large swell and mechanical difficulties. 

USGS scientists deploy the CHIRP seismic package behind the boat, where it will be towed for the next week. This unit contains both the seismic source and receiver.

Aaron takes in the sunrise while steaming out to the first coring station of the cruise.

All told, three datasets were successfully collected from Astoria Canyon, and this is a big step forward in understanding what phenomena drive sediment from the continental shelf to the deep ocean. We’re excited to begin sharing results!

Aaron enjoying the little things on the ride home.

CERMIT the tripod has landed!

The sediment dynamics group has been thinking deep thoughts lately–170 meters deep, to be exact. This winter, the lab outfitted a new benthic tripod frame with instruments to quantify sediment transport in Astoria Canyon, the submarine counterpart to the Columbia River. Fast forward to this May, the lab hitched a ride on the RV Oceanus for a week and set our tripod in the head of the Canyon to record a summer of canyon events and processes. While the Oceanus pitched and rolled a few extra degrees with its heavy lift crane atop the second story, the ship and its crew were wonderful help in nestling our tripod safely into the narrow canyon head.

Both amphibious and gangly, we believe the acronym CERMIT will stick (Canyon Edge ReMote In-situ Tripod), though fans should feel free to write in with their suggestions. CERMIT is outfitted with a long list of additional acronyms: multiple ADCPs, OBSs, CTDs, an ABS, a LISST, and more. These instruments will tell us precisely where and how fast the water is moving, and the concentration of sediment along for the ride. This summer, with a bit of luck, we will catch a few of the sediment-gravity flows that travel through Astoria Canyon, and determine what caused them: earthquakes, dredging for fish, or the (less-and-less) mighty Columbia may be the culprits. This information, in turn, helps our lab and other geologists interpret sedimentary deposits nearby and across the globe.

Stay tuned for its recovery and results this September!

UW vans arrive at the Oceanus carrying the tripod (deconstructed for travel). After this photo was taken, we got to work assembling it in the sunshine!

After construction on the dock, a crane brings the tripod aboard the Oceanus.

On the morning of deployment, the tripod is moved under the A-frame for lowering.

The tripod sneaks overboard, with everyone thankful for small swell.

Goodbye for now, CERMIT!

Science Writing for Diverse Audiences

This quarter, I’m up at Friday Harbor Labs teaching Science Writing for Diverse Audiences. As a class, we are exploring effective ways to read, write, and commicate science – all the way from peer-reviewed articles to op-eds and blog posts.

Friday Harbor is an excellent place to find inspiration to write. This past week, we headed out on the R/V Centennial to explore ecosystems around the island. We dug through sand and shell hash to get our hands on wriggly sand lances. We sifted through dredge material to find slime stars and anemomes. And, we gazed through microscopes to spot a myriad of zooplankton. The students’ enthusiasm clearly demonstrated their curioisity and love of natural science. We practice effectivelly describing our experiences with thoughtfully structured sentences, active verbs, and descriptive adjectives – skills that are needed to write well-received science articles.

Students explore rocks and organisms pulled up from the seabed.

Zooplankton under a microscope were displayed for all of us to see and discuss.

Students practice describing what they see in words.

But, this group of students has self selected to be here, and we’ve discussed that not everyone shares our views of science. Perspective colors how science is performed and perceived. Even within this self-selected classroom, students represent diverse views of science. As individuals, we tend to see science as beautiful and inviting. But, our families and cultures tend to see science more as a means to financial gain, often with devious conotations.

Students describe their own, their family’s, and their identified culture’s perception of science.

So, to add to our list of writing skills, we also practice how to frame our writing to fit our audience’s perspective. Research shows that scientists are often viewed as trustworthy, but cold. So, to present ourselves as authors that are both competent and warm, we practice contructing narrative arcs and adding humor and personality.

The quarter isn’t even half way over, and the students  are already better writers. Their arguments are persuasive, their desciptions are vivid, and their confidence is rising. I expect to see great things from this group. After all, science is often not driven by the best scientists, but instead by the best communicators.

Written by Robin McLachlan

Cooking Myanmar Food in Seattle!

Our lab has an ongoing research project examining sediment dynamics within the mangrove forests and distributary channels of the Ayeyarwady Delta in Myanmar.  During each of our field efforts we are enchanted by the food of Myanmar, which has hints of Thai, Chinese, or Indian influence, but is ultimately a cuisine all its own.

After tracking down a number of hard-to-find ingredients, we gathered to create our Burmese feast right here in Seattle.  In the end we made Yinmabin-Chowle Kyattha (chicken curry with okra), julienne green beans with garlic, Bottle gourd soup, and Shrimp Tom Yum Goong Soup.  This last dish is actually a Thai classic, but we made it as an homage to our favorite Thai Restaurant in all of Myanmar, the famous “G7 Gym and Restaurant” in the city of Pathein, located on the westernmost distributary of the Ayeyarwady Delta.

While we can’t claim to have mastered any of these dishes, it was fun to bring a bit of Myanmar cuisine to friends and family back here in Seattle.