Ocean Networks Canada - ddl

Expedition 2019: Highlights Story Map

duncanlowrie@uvic.ca — Thu, 14 Nov 2019 19:36:10 +0000

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Cool tech, hard science and daring innovation - Expedition 2017: Wiring the Abyss

kshoemak@uvic.ca — Thu, 27 Apr 2017 20:59:16 +0000

Ocean exploration is as exciting and complex as traveling into outer space. It involves cool tech, hard science, daring innovation, and a large team of highly qualified personnel. And thanks to underwater cameras and telepresence technology, the public can participate in Ocean Networks Canada’s (ONC) quest to know the ocean.

Starting on 28 April, Expedition 2017: Wiring the Abyss is ONC’s first major expedition of the year. This ten-day operation involves a team of 35 scientists, engineers, technicians, and data specialists who will live aboard the Canadian Coast Guard Vessel John P. Tully (Figure 1).

Figure 1. Canadian Coast Guard Vessel John P. Tully.

Conducting around the clock operations with robots, high tech sensors, instruments, and cameras, the team’s (Figure 2) mission is to maintain, improve, and install instrumentation on ONC’s west coast cabled observing systems: Saanich Inlet, Strait of Georgia, Endeavour hydrothermal vent field⎯which is Canada’s first marine protected area, Clayoquot Slope, and Folger Passage.

Figure 2. All hands on deck: ONC’s Associate Director of Marine Operations Ian Kulin (left) supervises the Marine Technology Centre team as they prepare hi-tech gear for Expedition 2017: Wiring the Abyss.

Expedition 2017: Wiring the Abyss starts 28 April

Highlights for the first leg of the 2017 Wiring the Abyss expedition include:

The installation of an innovative new monitoring experiment in the Strait of Georgia to find out if fish talk. This collaborative experiment to improve our understanding of fish abundance, variations, and interactions combines imaging, sonar, and video (Figure 3). Read more...

Figure 3. The instrument platform for the fish acoustics and imaging experiment will be deployed in the Strait of Georgia. The platform includes a mounted video camera, LED lights, ARIS dual frequency sonar (acoustic camera), subsea instrument interface module (SIIM), and underwater power/communications cable. A hydrophone will be located within the field of view of both the video and acoustic cameras, so that sounds generated by fishes will be easily associated with camera images.

Ongoing maintenance and improvements to the Natural Resources Canada delta dynamics laboratory (Figure 4), which measures live underwater turbidity currents in the Fraser River delta. A published study on the unique research findings of this instrument was recently included in the science journal Sedimentology’s 2016 Editor's Top Ten Picks. Find out more...

Figure 4. The newly redesigned delta dynamics laboratory platform prior to deployment in 2016.

Preparations at the Endeavour hydrothermal vent field (Figure 5) will significantly expand ONC’s instrumentation, allowing us to better understand and monitor this remote marine protected area. With support from the Canadian Foundation for Innovation’s Leading Edge Fund, marine geologist Dr. Laurence Coogan will lead a consortium of ten principal researchers from seven institutions across North America to further investigate how mid-ocean ridges work. Coogan is ONC’s Theme Leader for Interconnections Among the Seafloor, Ocean, and Atmosphere. Find out more...

Figure 5. New instrumentation at Endeavour hydrothermal vent field will improve our understanding of how mid-ocean ridges work. Pictured: Ifremer’s Tempo mini instrument platform.

This joint expedition will be co-led by ONC and Natural Resources Canada using the Canadian Coast Guard Ship John P. Tully and Pelagic Research Services newly redesigned remotely operated vehicle (ROV) Odysseus (Figure 6).

Figure 6. Pelagic Research Services CEO Ed Cassano inspects the newly redesigned ROV Odysseus, equipped with state-of-the-art tech including a SubC 1Cam Alpha (MK5) HD fiber optic camera.

LIVE DIVE WITH US!

Jump into the deep sea without getting wet! Starting 28 April, the public can join ONC in the ROV control centre and explore the sights and sounds of ocean research.

Expedition 2017: Wiring the Abyss dates

Leg 1: 28 April – 10 May

Leg 2: 7 June – 26 June

Tumbling to success: delta dynamics laboratory becomes scientific highlight

linzhill@uvic.ca — Mon, 24 Apr 2017 21:01:23 +0000

How do you study a moving wall of water and sediment the size of a truck traveling at 30 kilometers per hour? A paper about a spectacular Ocean Networks Canada (ONC) dataset was recently selected as one of science journal Sedimentology’s Top 10 articles of 2016, as an example showcasing “good practice, innovative approaches, and noteworthy advances of our science.” Congratulations to marine geoscientist Gwyn Lintern (Figure 1) and colleagues from Natural Resources Canada who published this paper on the tumbling delta dynamics laboratory platform.

Figure 1. A man outstanding in his field: Natural Resources Canada marine geoscientist Gwyn Lintern.

The Fraser River delta is known for its dynamic nature: laden with thick sediment deposited on its journey from source to sea, underwater landslides occur regularly, particularly during the spring freshet season when glacier snowmelt and spring runoff dramatically quickens and thickens the river flow. In 2008, ONC installed the delta dynamics laboratory in the mouth of the river delta (Figure 2) to capture the dynamics of these events.

Figure 2. The delta dynamics laboratory is deployed at the mouth of the Fraser River delta, facing upslope to monitor and measure the full force of seasonal turbidity events.

In 2012, a strong underwater landslide⎯known as a turbidity current⎯took hold of the one-tonne delta dynamics laboratory platform, and no-one anticipated what would happen next. The sediment-rich torrent of fast-moving water grabbed the platform, turned it over several times, and deposited it 75 metres down the slope. The Internet-connected instrument recorded three platform rolls before the cable connection broke, about 30 seconds into the event.

A challenge becomes an opportunity

Thanks to ONC’s real-time cabled connection, project lead Gwyn Lintern was aware of the tumbling event the moment it happened; this allowed him to promptly launch a follow-up expedition to investigate the area and take sediment samples.

Figure 3. The damaged delta dynamics laboratory platform being recovered and inspected following its dramatic tumbling event during the spring tide freshet.

Despite losing an instrument platform (Figure 3), Lintern was excited to see the last recorded data (Figure 4). While the platform was tumbling and rolling⎯but still connected⎯it presented an unexpected opportunity to sample a range of water depth zones at various orientations within this turbidity current. The result was a valuable set of profiles of sediment concentrations and water velocity, data that are essential to understanding the nature of these complex events.

Figure 4. The final minutes of data from the delta dynamics laboratory platform, 5 June 2012.

The long road from data to science to recognition

Analysing scientific data is a painstaking process. It took Lintern and his team several years to analyze the data so that the results could be published, but based on the positive reviews about the merit of this study, the wait was well worth it.

A summary of the unique findings in the 2016 paper include:

Details of the turbidity current’s dimensions (one to four metres high) and speed (six to nine metres per second), which is the equivalent of a large truck travelling at 21-32 kilometers per hour.
An understanding that the Fraser River delta’s turbidity currents are strong enough to tumble a one-tonne platform.
Evidence that this dynamic turbidity current did not significantly change the shape of the seafloor.
Indications that the conditions that trigger large turbidity currents (such as spring tides during the freshet) are now somewhat predictable. In fact, on the same day three years later, a re-designed platform (Figure 5) slid again during a turbidity event, but this time without tumbling, and it remained connected.

Figure 5. During the 2015 spring tide freshet, the redesigned delta dynamics laboratory platform slid downslope without tumbling or being disconnected.

Ultimately, with these significant findings and positive paper reviews, it did not come as a total surprise to learn that this paper was selected as one of Sedimentology’s top 10 articles.

Read the Sedimentology article: "Powerful unconfined turbidity current captured by cabled observatory on the Fraser River delta slope, British Columbia, Canada" by D.G. Lintern, P.R. Hill and C. Stacey, published in 2016; DOI: 10.1111/sed.12262. Lintern is continuing his studies in this area (Figure 6).

Figure 6. In October 2016, a newly redesigned delta dynamics laboratory platform was deployed. It is one of the largest platforms on ONC’s coastal network, weighing two tonnes and measuring six meters in length. Its extended leg posts anchor the platform 0.5 metres into the seabed, and it is equipped with over a dozen sonars intended to provide a fuller picture of turbidity events.

During Expedition 2017: Wiring the Abyss, the delta dynamics laboratory platform will receive its annual maintenance and upgrades. This Strait of Georgia location will also become the new home for an innovative field experiment to study fish behaviour through sound and imaging.

A Tenth Anniversary Inshore Maintenance Cruise

mkasprzik@oceannetworks.ca — Wed, 01 Jun 2016 17:01:19 +0000

The Canadian Coast Guard Ship John P. Tully in Saanich Inlet.

Ocean Networks Canada's tenth annual expedition season began on 28 April 2016 with an 8-day cruise to maintain the ocean observing instrumentation and platforms in Saanich Inlet and the Strait of Georgia. The Canadian Coast Guard Ship John P. Tully and the ITB Subsea Remotely Operated Vehicle (ROV) Oceanic Explorer supported the recovery, repair and deployment of seafloor installations and experiments, complemented by scientific sampling.

The Saanich Inlet Program in redeployed at 100m depth, following its 10th birthday maintenance tune-up.

Measuring Turbidity Currents in the Fraser Delta.

One highlight of this year’s inshore cruise was the repair and upgrade to the Fraser Delta Dynamics Laboratory site, originally deployed in 2008. The Fraser River delta is known for its dynamic nature: laden with thick sediment deposited on its journey from source to sea, subsea landslides occur regularly, particularly during the spring freshet season, when glacier snowmelt dramatically quickens the river flow. Our annual inshore expedition is timed to coincide with the spring freshet swells and Natural Resources Canada (NRC) leads several research programs studying these extreme events, known as turbidity currents.

On 5 June 2012, an avalanche of fluidized sediment displaced the delta dynamics instrument platform and severed it from its cable. Fortunately, data recorded as it tumbled down the slope enabled a reconstruction of the flow. Dr. Gwyn Lintern from Natural Resources Canada (NRCan) recently published a paper about this event.

Dr Gwyn Lintern (right) is one of the NRCAN scientists studying turbidity currents in the Fraser delta (2013).

“Turbidity currents are very important for moving sediment from deltas to offshore. Triggered by a number of mechanisms, these underwater avalanches cause millions of dollars in damage to subsea cables and pipelines every year. Historical turbidity current deposits can tell scientists about the frequency of past earthquakes and coastal underwater ground failures. Being both underwater and sporadic, they are notoriously difficult to monitor, and despite their importance only a handful of observations are available Worldwide.

Using Ocean Networks Canada, we were able to design experiments to capture turbidity current flows. We not only have the ability to measure them, but have gathered data to be able to determine what triggers the flows, and we have in fact successfully predicted when they will occur.

At the same time, the instruments we have on the delta front tell us how much sediment is deposited from the Fraser River, and which direction that sediment is being transported. The latest deployment is designed to also provide information about natural submarine discharge of groundwater from beneath the lower mainland.” Dr. Gwyn Lintern, Natural Resources Canada.

Dr. Gwyn Lintern supervises maintenance of the Seismic Liquefaction In-situ Penetrometer (SLIP).

A number of instruments on the delta dynamics platform were overhauled and deployed, including the seismic liquefaction in-situ penetrometer. This instrument includes piezometers to measure pressure in the water column, at the seafloor and at two points below the seafloor. These measurements are captured in real-time and can indicate an imminent underwater landslide.

Deploying the Seismic Liquefaction In-situ Penetrometer (SLIP).

Also deployed this year was an autonomous Aquascat platform, which uses sound to determine the size and stability of the settling sediment. Monitoring the stability of this turbid slope, and understanding how and when it can fail supports marine infrastructure and safety.

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Deployment of the NRC autonomous platform with the Aquascat instrument system.

The last of the pigs: the end of a forensic chapter in Saanich Inlet.

Our 10-year relationship with the forensic pigs came to a close during this expedition, as we picked up our final deployment. After a year decomposing at 300 m in the Salish Sea, all that is left are bones and the creatures that colonized the carcass.

The final recovery of the Central Strait of Georgia forensic platform.

Since 2006, Simon Fraser University forensic criminologist Dr. Gail Anderson has been using pigs to mimic the decomposition of human bodies in local seas. A total of 18 pigs were deployed in the Strait of Georgia over 10 years, helping to solve crimes and shed light on the mystery of the severed feet in British Columbia. There is a plan to deploy more pigs off the west coast of Vancouver Island, where Dr. Anderson will be able to monitor the carcasses at up to 2700 metre depths. Read more about Dr. Anderson’s experiments here.

Unusually anoxic waters measured by annual benthic hypoxia transect.

For the 11th time in 11 years, University of Victoria scientists Jackson Chu and Verena Tunnicliffe repeated their benthic hypoxia transect in Saanich Inlet. Using remotely operated vehicles (ROVs) equipped with oxygen sensors, they mapped the natural oxygen levels in the habitat of dozens of species of benthic fish and invertebrates. Their ecological approach aims to answer three questions: (1) what oxygen levels do benthic fish and invertebrates naturally occur? (2) Under what habitat conditions is oxygen ‘too low’ (i.e. hypoxic) for these animals? And (3) how do the animals respond when their habitat becomes hypoxic?

Horizontal seafloor oxygen profile.

Conditions at the study site were unusual for early May: anoxic waters (containing zero oxygen) had already expanded to the middle of the transect line, ~100 m bottom depth (see Benthic oxygen profiles graph). Although seasonal expansion of anoxic and hypoxic waters is normal in Saanich inlet, this usually occurs much later in the summer season. A direct consequence of hypoxia expansion is the shrinkage of viable habitat for the fish and invertebrates in this ecosystem. Their habitat becomes compressed into shallower depths as the animals redistribute to avoid the expanding low oxygen waters.

A hypoxia tolerant fish: Slender Sole (Lyopsetta exilis). Photo by Jackson Chu (University of Victoria).

During their transect experiments, Chu and Tunnicliffe tracked the distributions of the hypoxia (low oxygen) tolerant slender sole (Lyopsetta exilis) to provide a quantifiable indicator of the extent of habitat compression. Slender sole is the first fish species encountered when surveying from the deep to shallow depths of the survey. For example, during the May 2013 hypoxia transect (a relatively ‘normal year’), slender sole first appeared at 123 m depth. This year, slender sole did not appear until 96 m, indicating a shoaling of their habitat towards shallower waters by ~20%. Because most of the seasonal de-oxygenation has yet to occur this year, the severity of the hypoxia expansion may increase. An additional survey would be required to confirm the full extent of habitat compression during this outlier year. Read more about Jackson Chu’s research here.

Other instruments maintained and deployed during this inshore cruise include the bottom boundary layer experiment, a new high frequency hydrophone at Delta node, and calibration of the new codar station at Georgina Point, Mayne Island.

The offshore cruise Expedition 2016: Wiring the Abyss to service, upgrade and maintain the NEPTUNE array, runs from 12-30 May (Leg 1) and then 12-24 June 2016 (Leg 2).

Related stories:

Fraser Delta: a dynamic environment
Delta Dynamic Laboratory Lost and Found
Newer, greater capacity for the Delta Dynamics Lab
Spring Expedition 2015: ONC heads back to sea

Newer, greater capacity for the Delta Dynamics Lab

vkeast@uvic.ca — Tue, 28 Apr 2015 19:17:57 +0000

ONC Spring Expedition 2015 – March 28 to April 2 at the Strait of Georgia Observatory

One of the major goals of this spring expedition was to lay one kilometre of new fibre optic cable at the Delta Dynamics Lab (DDL) as the original copper-based wire had reached maximum capacity for data transfer. Natural Resources Canada (NRCan) has been working with DDL data since 2008 and also providing ship time for one expedition per year on the coastal observatory to assist with ONC’s science projects.

Highlightng this spring's expedition: the new DDL extension cable awaits installation.

Gwyn Lintern, marine geoscientist with NRCan’s Geological Survey of Canada in Sidney, B.C., knows well that slope failures are notoriously difficult to measure and require very high bandwidths for long periods of time.

“By using the new ONC cable, we now have high bandwidth capabilities,” says Dr. Lintern, “and we’ve become one of very few organizations worldwide capable of measuring underwater live underwater mass sediment transport events. This new fibre optic cable will allow greater capacity to transmit data from our Delta Dynamics Lab, through ONC to the NRCan offices.”

The ongoing long-term studies of shifting sediments at the mouth of the Fraser River continue to inform scientists’ understanding of underwater landslides and their effect on BC’s coastal waterways and communities. NRCan has published numerous scientific papers, using the data collected over the ONC network, on subjects such as delta sedimentation patterns and slope stability.

Read more about NRCan activities at the DDL: Connecting with the Strait of Georgia (Lintern et. al. 2008)

Tully Leg 1 Summary: Apr-May 2013

dwowens@uvic.ca — Fri, 10 May 2013 07:00:00 +0000

Today marked the end of Leg 1 - servicing installations in the Salish Sea - wrapped up after a successful 10 days of operations. At 09:00 the newly arrived leg 2 crew stood in the sun on dock with the happy, but tired, leg 1 crew. We began loading our gear and instruments right away with the ship's crane and finished at 14:00. It took us until evening to rearrange it like a giant block puzzle and tie it all down. All those hours playing TETRIS finally paid off.

The CanPac ROV Team spent the day conducting maintenance on the Remotely Operated Vehicle and working through the various tooling required for leg 2.

The big event of the day was the installation and configuration of the satellite system which will enable high bandwidth communication for leg 2. We began in the morning by setting up network equipment in anticipation of the satellite system's arrival. The frame finally arrived on the dock at 13:30 enabling the pedestal, dish and ISO connectors to be installed. The entire assembly was hoisted onto the CanPac Divers containers on the aft deck at 16:15 with most of the science crew outside watching.

Cable runs and terminations were completed by 18:30 and the system was powered up. Calibrations, verifications and network testing continued for several more hours. Testing included clockwise and counter-clockwise spin tests with the Tully, a.k.a. doing donuts in Pat Bay. The spin tests confirmed we have a 15 degree dead zone facing the ship's mast. The system is now functioning (enabling us to send you this log), but requires a few tweaks in the morning to get the streaming video online. We have two VoIP phones with Houston area codes, but don't expect a Texas accent when you call, and saying "Houston, we have a problem!" is not funny to us.

The satellite technicians from Oceaneering, Hung Phan and Gary Cheramie, along with Ocean Networks Canada's Nic Scott were transferred to shore after a long, but ultimately successful, day of system setup. We are currently underway to Barkley Canyon Upper Slope, looking forward to our first day of offshore operations tomorrow.

Here is a brief summary of the accomplishments during the maintenance of the VENUS installations:

By the numbers

13 Days
28 Dives
5 ROV Pilots
23 Tully crew
23 Science party participants (full and part-time)
3 CTD Rosette casts
12 cabled platforms serviced and 11 re-deployed
3 autonomous moorings serviced: two recovered, one redeployed
2 extension cables laid and connected to service Fraser River Delta Site
76 instruments serviced during the leg

Saanich Inlet

Bottom Boundary Layer (BBL) Platform recovered
DISCo Digital Stills Camera System recovered
HD Forensics Camera: Recovered and redeployed
MicroSquid Benthic Oxygen Flux Platform – recovered and redeployed (twice) Autonomous Sill Mooring - redeployed

Strait of Georgia – Central

Bottom Boundary Layer Platform deployed
Autonomous CTD & DO mooring recovered

Strait of Georgia – East

Delta Extension Cable (south) end found and connected
IOS Hydrophone Array deployed
ONCCEE Hydrophone Array deployed
Autonomous CTD & DO mooring recovered

Strait of Georgia – Delta

Delta Extension Cable (north) end found and connected to Delta Node
Delta Node deployed
Delta Dynamics Laboratory (DDL) cable laid
DDL Platform deployed
ONCCEE Hydrophone Array deployed
Seismic Liquefaction In situ Penetrometer (SLIP) deployed

Science activities

Sonar surveys of Howe Sound
Sonar Surveys of Delta Slope
ROV transect survey from Saanich Inlet into Patricia Bay
3 ROV transect surveys of Saanich Inlet cliffs in the Squally Reach area

Fraser Delta: a Dynamic Environment

dwowens@uvic.ca — Sat, 27 Apr 2013 07:00:00 +0000

River deltas are known for their dynamic nature. Most of the rivers naturally carry silt that eventually enters the ocean and settles at the bottom, continuously changing the shape of the seabed. Seasonal events, such as freshets - when glaciers’ snowmelt enters the river stream - are the time when the seafloor at deltas can change rapidly causing events called “slope failures” or “subsea landslides”. Fraser River delta is one such location where subsea landslides occur regularly, in particular during the spring freshet season (May-June). Natural Resources Canada leads several research programs studying seafloor processes and conducts regular surveys of the delta area.

Coastal communities and infrastructure surrounding the southern Strait of Georgia would be at risk in the case of a submarine slope failure on the foreslope of the Fraser River delta and, therefore, scientific programs are essential to better understand seafloor processes.

The monitoring of the slope stability is accomplished by measuring pressure beneath the seabed and failure events using custom-designed instruments. In the past, it has been difficult to measure and capture these relatively infrequent failure events by using short term moored instruments.

Deployment and networking of the present instrument packages is facilitated by Ocean Networks Canada's Salish Sea Observatory. The observatory runs a fibre-optic cable in the Strait of Georgia allowing real time observations. Communication and power provided by the observatory allows scientists to measure key parameters in great detail and for long time periods (milliseconds to years).

The goal of the monitoring program is to gain a better understanding of the conditioning factors and triggers of slope failure, and to develop instrumentation for monitoring these. Eventually this knowledge and instrumentation could be used to develop early warning systems for large and destructive failures in places where they are known to occur.

Research History

The technology of measuring all variables at all time scales is essential, as some of the conditioning mechanisms can take months to years to form, yet the triggers and slope failure take place over just a few seconds.

In 2008 the Delta Dynamics Laboratory (DDL) was placed on the upper slope of the delta. In both June and July 2008 between 20 and 40 cm of the seabed disappeared from beneath the delta dynamics lab. On the same weekend (same tides) five years later, the delta dynamics lab, now located at the bottom of the slope, was plucked off the seabed and sent tumbling. As it tumbled it measured in great detail the leading edge of the gravity flow which carried it downslope.

One of the factors which leads to slope instability is simply fast build up of sediment on a delta front from river deposition. Profilers on the delta dynamics lab show this beautifully as a cascade of sediment which settles from the surface plume during slack tides. It gathers into thick muddy concentrations at the bottom over the next couple of hours.

Instruments and Data

The variety of factors involved in generating slope failures at the Fraser Delta has made investigations difficult. A number of researchers with different expertise have made use of many different classes of instruments over the past two decades. The Seismic Liquefaction In Situ Penetrometer (SLIP) instruments include piezometers to measure pressures, in the water column and within the bed. These penetrate to a depth of 5m beneath the seafloor, at water depths down the delta slope between 10m and 140m. Prototype SLIP instruments have been deployed in this area during survey cruises, with the first fully deployed SLIP deployed in 2013. Accelerometers measures seismic activity, and along with inclinometers, measures associated movements (strain). Seasonal groundwater flows are measured by the combination of piezometers and thermistors.

In addition to the SLIP instruments, there is a Delta Dynamics Laboratory (DDL) and a mini-node, which provide additional environmental information for the slope stability work as well as on general delta (sediment) processes. The delta mini-node at the base of the slope provides hydrophones to listen for landslides and earthquakes. The DDL contains mainly standard oceanographic instruments, including: a CTD to measure water properties, optical backscatter sensors to measure sediment transport at two different heights, single point current meters to measure currents at those same heights, upward looking ADCP to measure currents and sediment concentrations throughout the water column, acoustic profiler to measure sediment concentrations and gas bubbles (as well as zooplankton and fish) throughout the water column, scanning sonars to measure bedforms, and a laser instrument for measuring suspended grain sizes and concentrations.

Relevant References

Ayranci K., Lintern G.D., Hill P.R., Dashtgard S.A. 2012. Tide-supported gravity flows on the upper delta front, Fraser River Delta, Canada. Marine Geology. v.326-328, p. 166-170.

Lintern D.G., Hill P.R. 2010. An underwater laboratory at the Fraser River delta. EOS, Transactions, AGU 91 (38): 333-44.

Hill P.R., Conway K., Lintern D.G., Meule S., Picard K., Barrie J.V. 2008. Sedimentary processes and sediment dispersal in the southern Strait of Georgia, BC, Canada. Marine Environmental Research 66: S39-48.

Lintern D.G. 2008. Connecting with the Strait of Georgia – an overview of activities supported by NRCan using the VENUS project. Abstract. Geophysical Research Abstract Vo.10, EGU2008-A-11537.

Lintern D.G., Hill P.R., Conway K. 2008. Using the VENUS underwater network to assess conditions leading to slope failures. In Proceedings of the IV the Canadian Conference on Geo-hazards: from causes to management. (Eds), Locat J. et al. Presse de l’Universite Laval, 594 p.

Delta Cable is Back for Repair

rlat@uvic.ca — Thu, 18 Oct 2012 07:00:00 +0000

The orange reel holds over 5 km of extension cable on the deck of the “Georgia Transporter” powered barge after a successful recovery. This cable supplies power and a communication link from the East Node in the Strait of Georgia (175m) to an instrument platform near the mouth of the Fraser River. This cable was damaged in June 2012 by an underwater landslide and will be repaired and then redeployed in April 2013.

DDL Lost and Found

rlat@uvic.ca — Tue, 03 Jul 2012 07:00:00 +0000

Late in the afternoon of 4 June 2012 PDT (early on June 5 UTC), VENUS lost contact with the Delta Dynamics Laboratory (DDL) platform, an NRCan lead research initiative studying delta slope stability. The image shows the last minutes of data from the platform. 2 Nortek Vector ADVs connected to the DDL (one on the VIP frame and a second remotely deployed on its own tripod) were sampling at 16 and 8 Hz respectively. Shown here are the high-sample rate (16Hz) pressure readings from the downward facing Nortek Vector on the VIP and the 1 Hz internal compass headings (which may be suspect as the instrument becomes inverted). The data suggest the entire platform was tumbled several times westward into deeper water, until the data streams end at 00:04:03 [UTC].

Over the last two weeks VENUS and NRCan have been assessing the event through replaying the marine traffic scenarios, taking sediment cores, conducting multibeam surveys, assessing private vessel provided sonar data and most recently side-scan surveys of the area. On June 28, Adrian Round, working with Terra Remote, conducted 500kHz side-scan surveys that located the platform about 60m from its original location.

Although further diagnoses will continue, we plan to recover and assess the condition of the entire package during our August maintenance cruise. Dr. Gwyn Lintern at NRCan is investigating the cause of the event and we anticipate some interesting research results. For our initial investigations we are thankful to Department of Fisheries and Oceans scientists and crew on board the CCGS John P. Tully for collecting sediment cores, the crew of the University of New Brunswick survey vessel Heron for multibeam survey, the core analysis facility at Geological Survey of Canada Pacific for a quick response, a captain of a local Seaspan commercial vessel who sent in his observations, and the Marine Communications and Traffic Services, Canadian Coastguard.

Imagenex Last 24 Hours Sector Sonar Plots Now Available

rlat@uvic.ca — Mon, 04 Jun 2012 07:00:00 +0000

Deployed at our Fraser Delta site in the Strait of Georgia are various sonar systems. In addition to the upward looking echo-sounder (200 kHz ZAP), we have a downward looking scanning sonar built by Imagenex. Shown here is a series of single scan images, and when compiled into an animation, the time-lapsed set of hourly images shows the changes detected by the sonar. This scanning sonar sweeps out a radial scan of the ocean bottom to detect and monitor changes in the bedforms. Seen in these images is the corner of the instrument platform (lower left corner), and bottom roughness out towards the right. In the animations from May and June, we also see the daily occurrence of a high concentration of suspended sediment, when the entire image shows yellow and orange backscatter. These events, which occur during the peak freshet of the Fraser River, are associated with the downward settling of the river sediment after low tide.

Ocean Networks Canada - ddl

Expedition 2019: Highlights Story Map

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Cool tech, hard science and daring innovation - Expedition 2017: Wiring the Abyss

Expedition 2017: Wiring the Abyss starts 28 April

LIVE DIVE WITH US!

Expedition 2017: Wiring the Abyss dates

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Tumbling to success: delta dynamics laboratory becomes scientific highlight

A challenge becomes an opportunity

The long road from data to science to recognition

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A Tenth Anniversary Inshore Maintenance Cruise

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Newer, greater capacity for the Delta Dynamics Lab

ONC Spring Expedition 2015 – March 28 to April 2 at the Strait of Georgia Observatory

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Tully Leg 1 Summary: Apr-May 2013

By the numbers

Saanich Inlet

Strait of Georgia – Central

Strait of Georgia – East

Strait of Georgia – Delta

Science activities

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Fraser Delta: a Dynamic Environment

Research History

Instruments and Data

Relevant References

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Delta Cable is Back for Repair

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DDL Lost and Found

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Imagenex Last 24 Hours Sector Sonar Plots Now Available

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