On Tuesday I had the opportunity to fly over the Elwha watershed as part of a flight purchased by Nancy Fowler of Port Townsend as part of the Fish on the Fence fundraiser for the Feiro Marine Life Center. I've flown the valley multiple times now, and it never gets old, but given the scale of the change in the system I found myself wanting to dig up photos from some of the earlier flights I went on.
I started flying over the Elwha systematically in 2004 as part of a coastal monitoring program I initiated at the Surfrider Foundation. Here is a shot from one of those flights, on 22 June 2005:
and another from more or less the same perspective from this Tuesday's flight:
We didn't routine fly over the reservoirs, but every now and again I had the chance. Here is a shot of from before the dam removal started (taken on 27 June 2011)of the lower reservoir:
and its not a perfect match, but here is the view during Tuesday's flight:
and for the upper reservoir from 27 June 2011:
and again, not a perfect match, but the view from Tuesday's flight:
A few months back I wrote about a survey of the Ledgewood Slide, a large deep-seated "rotational" slide on the west coast of Whidbey Island. During that survey I left a camera behind, which faithfully collected an image of the toe of the slide every hour during daylight hours. My interest was in determining how quickly the toe of that slide would erode, as well as the processes that are most responsible (high water versus waves, for example). And while survey data would be most useful, the time lapse is a great tool when you can't be there all the time measuring.
I was able to quickly revisit the site over the Memorial Day weekend, and while I didn't have time or tide for a survey I was able to recover the photos. Check it out:
There are a few marked episodes of erosion of the toe, occurring over the night on April 4-5, on April 10, and the night of April 28-29. All of these periods fall during spring tides (see water level observations from Port Townsend, below), with high astronomical tidal water level, suggesting that water level plays a critical role. This seems obvious, except to note that the last two days captured by this session, May 24-26, also feature very high tides but no obvious erosion events.
It therefore seems likely that wind, and specifically wind-generated local wind waves, played a role in those erosion events, and the wind data from Port Townsend seems to support this, with some notable spikes around April 4th, 10th and 29th.
Regardless, the bluff toe had changed dramatically. Notably, as the toe of the slide erodes it exposes more of the sand layer that was exposed as a relatively thin (~1-2 m) layer during my survey on 2 April. This material is likely a significant contributor to the budget of adjacent beaches...and it would be cool to get out and do a survey to look at profile and grain size change...just need to find a time to get out.
Here are a few photos I shot on May 26...
Steep and high sand scarps prevail across much of the toe of the slide at this point, which contrasts with the early toe, which was composed of a lot of uplifted clays.
A view from the top of the scarp looking down to the beach...a distance of ~6-7 meters
Another view of the scarp at the toe of the slide on 26 May
The beach to the north of the slide...appears sandier than before
A view of the beach to the south of the slide, taken on 26 May 2013 from the revetment. Below is a photo taken on 2 April 2013 taken from a point looking towards the slide from about MLLW. The photo above was shot from about where the stairs are in view right. Sandier beach?
Two things made me think its time for another update regarding shoreline change at the Elwha River delta. First I've finally had a few moments to do a bit of work with the profile data I've been collecting approximately twice per month (at four sites around the delta) since I started with Sea Grant in March 2011. Notably I've been wanting to add an analysis specifically looking at movement of the Mean Higher High Water contour as a proxy for the position of the shoreline. As the restoration continues our conceptual models suggest that erosion, especially to the east of the river mouth, should slow down and perhaps reverse as sediment is supplied to the shoreline. Its been very clear since about January that the beach at Line 164 (see map in attached below) was growing dramatically. This site is close enough to the river mouth, though, that it is possible that this accretion is less about alongshore transport processes and more about that site really becoming part of the expanding river mouth.
30 April 2013 aerial image of the Elwha River delta courtesy of Andy Ritchie, Olympic National Park. The four transect lines that I measure topography and grain size on every two weeks are shown in red.
As a result I've been particularly intrigued by patterns of shoreline change at Line 190, which is further to the east and at least a few hundred meters away from the large pile of sediment that deposited in front of the river mouth in December-January this winter. Even with an enhanced sediment supply to the coastal zone, which really kicked off in April of 2012, however, my data from late last year and early this year showed continued erosion at this site. Lately, however, (and this is the second thing that made me feel like its time for an update) I've started to "feel" like that section of the shoreline has stabilized a bit relative to how its been eroding in the recent past. I think that my profile data back me up a bit on that. I see the possibility in these data that rates of erosion at Line 190 (the green line in the lower right hand corner of the figure below) have slowed since about the middle of 2012, and that data from the first half of this year even suggests a possible pattern of accretion developing there.
Profiles from May 2011, 2012 and 2013 from four sites on the Elwha River delta (reference to map at lower left). Relative position of the MHHW contour (positive is accretion, negative is erosion) over time is shown at lower right.
The interesting thing here is that if there is a pattern of beach growth emerging at this site it is happening in a different way than the accretion at Line 164. At Line 164 its all about sand...huge amounts of sand. At Line 190 the entire intertidal zone is seemingly as coarse as its been for a good while. The photo below, for example, shows both an oblique of Line 190 (looking landward from about MLLW) from 2012 and 2013, as well as a grain size image from just about the mean sea level contour on the beach. So what is going on? Not sure, really, but it is possible to imagine that there is alongshore transport of sand, and perhaps gravel, from areas closer to the river mouth that are adding volume to the beach at Line 190...even without an obvious decrease in grain size on the surface of the beach.
Oblique images taken looking landward from about Mean Lower Low Water (top) and grain size images taken at about 1.40 m above MLLW on the beach (bottom) from May 2012 and 2013.
But the title of this post really says it all...this data collection effort will continue in the hopes that we can puzzle out how this dam removal will also act as a beach nourishment...and if it will reverse decades of erosion. This is an important question, since communities all over the nation and the world are increasingly grappling with questions about how to respond to projections of shoreline erosion due to climate change. Changes to the way that society manages sediment delivery to the coastal zone, via rivers primarily, is one possible way that some of that projected erosion of shorelines might be addressed in the future.
The "Keeling Curve" - atmospheric CO2 in the modern era (since 1958). These data underpin one of the lines of evidence that contemporary rising CO2 concentrations are due primarily to human activities.
It seemed like spring was all about climate change, and particularly various efforts around the Olympic Peninsula aimed at preparing for projected changes. I wrapped up two different climate change projects, a large climate impact assessment for the Olympic Coast National Marine Sanctuary, and another that I was a contributor for - a community impact assessment for the Jamestown S'Klallam Tribe. I am pretty proud of this last one - not only did I get to work with some truly phenomenal partners from Adaptation International and the Jamestown Tribe, but I am also proud to have participated in this first comprehensive community assessment to take place in coastal Washington outside of Puget Sound. Another notable event was the Clallam MRC's workshop on ocean acidification, which focused on current and future "acidification" of local marine waters, driven by increasing carbon dioxide concentrations in the atmosphere.
It seems to me that media reporting on climate change has turned a corner of sorts, and I feel that I've seen far more reporting this spring on science and assessment of global climate change. This Reuters article from today on a Nature Geoscience paper is a good example. It suggests that climate models most extreme projections (i.e. on the high end of their uncertainty) regarding atmospheric warming may be too high...seems like a positive, right? But the reason - that the oceans seem to be absorbing more heat than expected, has local ramifications. Even small increases in ocean temperature may have observable impacts including shifts in the range of marine species, and reduced productivity due to increasing stratification between the warmer surface layer and the colder water below it.
The data that set off the 400 ppm media blitz - CO2 concentration measured at Mauna Loa, Hawaii
These data, from the Scripps Institute of Oceanography and posted to www.climatecentral.org, suggest that the current level of atmospheric CO2 is anamalous over the 800,000 year record available by analyzing gases trapped in ice.
In light of this context, it seems worthwhile to at the very least bring the very best science to bear on the problem of projecting future climate, and use that information to plan for those changes. The OCNMS Sanctuary Advisory Committee discussed that very problem at their meeting on Friday, and I see leaders all over the Olympic Peninsula and in Washington State doing the same. I focus on the coastal implications of climate change - and there are many. One of the areas that I am interested in at the moment is the ways in which climate change, primarily through sea level rise and changes in storm pattens and wave climate, may compromise the ability of shorelines to act as effective barriers between communities and the ocean. To that end I've proposed a small shoreline monitoring program for the North Olympic Peninsula, to complement shoreline change data collected in SW Washington and Oregon. I put together the poster below on the program - check it out and let me know what you think...
Styrofoam...an increasingly common component of the intertidal ecosystem of the world's coastlines.
Initial estimates from this year's Olympic Coast Cleanup suggest that approximately 15 tons of debris were pulled off of Washington's beaches. A staggering amount, but definitely not a huge increase over previous years. One of the hypotheses out there regarding the potential of increased volumes of debris related to the Tohoku tsunami is that we would see spikes in these clean-up data...and that doesn't appear to be the case this year.
...and the other part of the modern beach, the plastic beverage bottle
This year's clean-up provided the same inspiring examples of community care and investment in the condition of Washington's outer coast. People came from all over the state (and out of the state), made a weekend of it, and dedicated hours and energy to pulling everything from chunks of styrofoam to 50 kg tires off of wilderness beaches. For the past few years I've worked the registration station at Three Rivers, serving beaches north and south of La Push. Many of the faces showing up to register have become familiar, and learning the stories of the people that come to the clean-up is one of the reasons that I love this event so much.
a local contribution to marine debris...likely from commercial fishing off of Washington's coast
Like last year I tried to get a sense of what was pulled off of those beaches in order to assess the degree to which patterns of debris are changing. Again, I was primarily interested in the "production rate" of those beaches, so like last year I turned to data collected by volunteers as they worked the beaches. We totaled 118 volunteers on "our" beaches this year (again: Rialto, First, Second and Third), and based on their estimates each volunteer averaged 19 pounds of debris, with a standard deviation of 14 pounds. Using the standard deviation as a measure of the uncertainty, I use that to estimate a total of 2280±1650 pounds collected over 6.6 miles of beach. On a per mile of beach basis (which is the metric that we attempted to use in our scenario development for the possible impact of tsunami debris), this equates to 0.17±0.12 tons/miles. We've estimated the "baseline" (i.e. before the tsunami debris) debris delivery to the beaches of Washington to be about 0.5 tons/mile. So this is another line of evidence to suggest that the Tohoku tsunami has not led to a significant and sustained spike in the amount of debris making landfall on the beach.
more fishing debris
That being said, its almost certain that some of the debris that was pulled off of the beach was, indeed, "tsunami debris". The first photo of this post shows a sub-sample of the styrofoam bits pulled off of Rialto Beach. There has been much speculation that pulses of styrofoam that made landfall in Washington starting last summer were derived at least in part from insulation material - from homes, businesses and other structures - released into the ocean by the destructive power of the tsunami. This material is particularly worrisome because it breaks apart fairly easily and some suspect has ecological impacts out of proportion with its relatively low mass. We don't know if there is more styrofoam this year than in previous years since those sorts of information aren't tracked carefully.
one of the finds of the day - a huge chunk of styrofoam that appeared to have been a part of an old dock or structure. Chunks of concrete were attached to it.
Another very cool part of this year's clean-up, and one that will hopefully provide much more detailed information on the mass and composition of debris recovered, was the work of a group of Western Washington University students at a selection of beaches (including Third Beach). As part of a project funded by the North Pacific Coast Marine Resource Committee they focused on carefully sorting and weighing debris.
students from Huxley College of Environmental Studies carefully sorted and measured much of the debris off of selected beaches as part of a project funded by the North Pacific Coast Marine Resource Committee
A view of the dumpster at the trailhead of Third Beach near the end of the day
The ProMark 200 RTK-DGPS system used for this survey leaning one one of the uplifted scarps along the edge of the slide. Those gravels on top of the scarp are the former high intertidal surface, uplifted 2-3 meters.
The Ledgewood Slide on Whidbey Island on March 27th was large enough to destroy at least one house and prompt the evacuation of more, and also to generate at least a blip on the national news scene. Bluffs are a predominant shore type in Washington State, and their failure - whether slow and creeping or large and catastrophic - is one of the many hazards that coastal residents of this state are subject to. Bluff erosion and failure is sort of a double-edged sword though - while a hazard to human infrastructure, the sediment supplied to beaches by bluff erosion is thought to be a building block for beaches and complex coastal habitats. As a result there can be tension between the desire to stabilize bluffs with armoring or other tools, and allow them to erode to support habitat restoration goals. In light of sea level rise projections, climate change projections related to increasing winter precipitation, and on-going construction of infrastructure on coastal bluffs it is likely that this tension will only amplify in the decades ahead.
Rebekah Sexton and Diana McCandless from WA DOE's CMAP program - about to get wet and collect more topography data than you can imagine.
For all of these reasons understanding how, when and why bluffs erode, and what sort of contribution they make to the coastal sediment budget are important research objectives in Washington. The Ledgewood slide, because of its scale and the deep-seated nature of the slide, generated significant interest amongst the small community of coastal geologists, geomorphologists, managers and others who think about these sorts of problems every day (see these two other blog posts on the slide, one by Dan McShane, and the other by the venerable Hugh Shipman, as well as the Washington DNR's Preliminary Report on the slide). As a result I carved aside a day (2 April 2013, six days after the slide) to join a few others from the WA DOE Coastal Monitoring and Analysis Program to investigate the slide. While the DOE staff (Rebekah Sexton and Diana McCandless) focused on collecting high resolution topography data on the beaches adjacent to the slide for post-processing, I decided to focus on collecting real-time topography data on the slide itself. I had two goals: 1) Add to the baseline data set that will allow us to track the evolution of the toe of the slide over time as it interacts with waves and tides, and 2) quantify the volume of sediment delivered to the coastal zone by the slide. Here I am providing some of the preliminary results and analysis from that short survey. To reiterate though, this is just a taster. Others are collecting reams of data and providing insight that should deliver an enhanced perspective on the slide.
The former log line from the high beach, uplifted to approximately 4 m above MHHW.
First, a bit on methods. All of these survey data were collected with a Peninsula College-owned Ashtech ProMark 200 RTK-DGPS system (PM200) on a survey pole (see photo above), receiving corrections through the Washington State Reference Network. Its always ideal to validate the RTK survey data against some other independent spatial data, preferably a monument with good published control. In this instance though there were no monuments adjacent to the site. As an alternative the PM200 survey data were compared to aerial LIDAR collected in 2001-2002 for the area around the slide, and available through the Puget Sound Lidar Consortium. Near the slide site 20-30 points were surveyed along a surface (the road leading down to the parking area north of the slide) that I though was likely there in 2001-2002, highly visible to the LIDAR sensor, and probably fairly stable over that 11 year intervening period. These 20-30 survey points were compared to the nearest individual LIDAR return and the measured elevations differenced to generate this distribution:
So this was good - an average 6 cm offset suggested that the PM200 and the LIDAR from 2001 were relatively close in the vertical...good enough for the purposes of this preliminary survey.
I focused on trying to collect cross-shore profiles from the water line as high as I could get on the slide, both adjacent to and on the slide, and then compared each to the 2001-2002 LIDAR data. Here is an example from a site in the middle of the slide (others are given at the end of this post):
As it turned out I was unable to survey high enough on the slide (due to vegetation) to get over the pre-slide surface (the LIDAR data). The slide toe was pushed 60-80 m seaward and so all of the areas I was surveying on the toe were over formerly sub-tidal or lower intertidal surfaces, and to make matters worse the 2001-2002 LIDAR in this area was collected during relatively high water - somewhere around 1.5 m above MLLW. Needing a pre-slide surface to calculate vertical changes against I turned to Dave Finlayson's Puget Sound DEM (also shown in the figure above). As is clear, though, this is a relatively coarse (10 m horizontal resolution) DEM and only roughly models the actual surface in the area of the slide.
Despite the coarse resolution of the Finlayson DEM it was the best available surface for most of the survey extent. Here are how all of the survey data compare to the DEM:
You can see from this map how I was unable to survey over the former beach surface along most of the slide. For comparison sake here is the comparison to the 2001 LIDAR data:
Since these LIDAR data were collected at relatively high water the only survey points that I collected that overlapped were on the upper beach adjacent to the slide.
Total volume contributed to the coastal zone? Well, kind of hard to get at with these data since I wasn't able to survey to the former MHHW contour and didn't have high resolution bathymetry to work with, not to mention how sparse my survey data were. However, based on the footprint of the slide now in the coastal zone (an estimated 21,260 m2 based on my preliminary survey), and assuming a mean difference between my survey data and the pre-slide surface (a loosely estimated 6 m based on eyeballing the profiles below), I estimate a contribution to the coastal zone (defined here as the area seaward of the former MHHW contour) of ~128,000 m3 of sediment. This is a VERY rough estimate (noting that a better estimate should come later from the higher resolution data collected by WA DOE), but if its close it represents a significant volumetric contribution to the intertidal zone. However, based on observations made of the slide it seemed to be composed of a large fraction of mud and silt which is unlikely to remain on the beach. And, of course, it remains to be seen if and how long it takes Puget Sound to redistribute this sediment.
Of course, one of the more interesting things about this slide was not necessarily its extent, or the volume it contributed to the coastal zone, but in how it slid, and the forms associated with it. I shot this video to try to capture some of the interesting features of the toe of the slide:
and here are the remaining profiles...all ten of them. If you are interested in my raw survey data email me at immiller@uw.edu and I can get them to you.
Today Steve Fradkin from Olympic National Park and I presented a well-attended Studium Generale lecture at Peninsula College in Port Angeles - on marine debris in general and "tsunami debris" in particular. While I babbled on trying to provide some background and context to tsunami debris Steve focused on the implications and removal of the Misawa dock that washed up in Olympic National Park. The Misawa dock gets its name from its point of origin, in Misawa Japan:
The harbor from which the Misawa docks originated. Of four docks, one did not leave Misawa Harbor, one was recovered on the coast of Oregon, and one was spotted off of Hawaii but subsequently lost.
As the Coastal Hazards Specialist for Washington Sea Grant I spend my time on research, education and outreach on topics like chronic erosion, climate change, tsunami and other coastal hazards. Current projects include:
1) monitoring the shoreline of the Elwha River delta to detect changes due to the Elwha Dam Removal
2) Assessing the influence of climate change on the resources of the Olympic Coast National Marine Sanctuary
3) Evaluating the impact of debris from the Tohoku tsunami on the shorelines of the Olympic Peninsula
