Friday, January 19, 2018

Big Waves




Yesterday the Washington coast was hammered by an potent combination of extraordinarily large and powerful waves, which coincided with a reasonably high astronomical tide and some storm surge. You can see these processes coming together (high tide was at roughly 1pm) in the video above, compiled from a webcam mounted on Kalaloch Lodge on Washington's Central Coast. This webcam is looking straight out the mouth of Kalaloch Creek, a small coastal creek, towards the ocean.  In the video you can see waves pulsing into Kalaloch Creek, mobilizing and transporting the massive jams of wood that line the beach and creek mouth there.  This storm led to at least one death, and a raft of incredible videos, photos and stories from along the coast.

How extreme were these waves? Pretty darn extreme. The Cape Elizabeth Buoy has been measuring waves just offshore of the Washington Coast since 1987, providing hourly estimates of significant wave height and other wave and weather parameters. To date the bouy has accumulated over 200,000 wave observations going back almost 20 years. The bouy estimated a peak significant wave height for this event of 9.9 m at 12:50 pm. There are only 14 larger wave observations on record, all associated with the "Great Coastal Gale" of December 3-5 2007.  I've plotted significant wave heights from Cape Elizabeth below, as a time series (top), and a histogram (bottom).




Friday, December 22, 2017

The Elwha Delta gets hammered



A couple of days ago John Gussman sent out some beautiful pictures of the Elwha River delta, most shot from his drone.  One of the things that really struck me was how much the morphology had evolved from the sort of classic crescent shape that has characterized the delta since the dam removal period, which is nicely illustrated in this 2015 aerial photo:

An aerial image of the Elwha delta taken 23 September 2015 by Andy Ritchie's PlaneCam

By contrast, in John's photo the bar to the east side of the river mouth is set quite a bit landward relative to the west side bar, giving the delta a somewhat lop-sided look.

So given this odd morphology I was stoked to find that my old creaky time-lapse cameras looking down at the river mouth had managed to shoot photos through December, capturing in particular the series of storms that hammered the delta around Thanksgiving (which included some river flooding).  Indeed, those cameras revealed that the eastern bar had been pushed landward quite rapidly between roughly December 1st and December 4th (check out the video above, or here).

The video below (and also here) is a time-lapse of the raw 30 minute photos (not averaged for the day), and suggest a few days of elevated water level and waves:



which also suggests that there was some rapid landward movement of the bar to the east of the river mouth between roughly December 1 and 4.  I happened to get some profile data on 5 December as well, and have one profile line that cut through the section of bar visible in this video, Line 156:

You can really see the migration of that bar in my profile data from Line 156:


These data suggest roughly 50 meters of landward migration between September and December!

Interestingly though, the beach at Line 164 (which is outside the field of view in the video, to the east) is far more stable:


Its not abundantly clear to me what drove the bar migration in early December - it wasn't really a period of extreme wind, water level wasn't really all that highFlow was still a bit elevated by early December, but the big peaks had occurred earlier, around Thanksgiving.  And waves, at least as suggested by the buoy out towards Neah Bay, weren't all that big:


This plot is significant wave heights measured all the way out at the mouth of the Strait, and while those wave heights around the 29th of November are indeed sizable (5.5 meters!), by the 4th things had calmed down.  Indeed, it seems like the convergence of forcing was really between November 26 and 29, but by my eye the time-lapse suggests that the bar really moved between Dec 1 and Dec 4.  Very cool...it will take a bit more digging to figure out what really happened here.

Thursday, December 7, 2017

When a King Tide Isn't so royal

Photo of Hollywood Beach taken during the "King Tide" on 6 December 2017
I love me some King Tides, and I love that we've built programs around appreciating and even viewing these sorts of events.  The concept is that we can use these high water events to understand future conditions, or learn something about the complex suite of processes that drives variations in marine water level in our neck of the woods.  I'm 100% in to both of those concepts.


Predicted water level due to astronomical tides in Port Angeles, Washington for the winter 2017-2018
The predicted marine water levels due to the astronomical tides for this winter in Port Angeles, WA (relative to Mean Lower Low Water, or MLLW) are shown above, and four "King Tide" periods stand out as the three humps on the top of the curve, where predicted water level exceeds 7.5 feet.  For reference, the mean higher high water (essentially the daily average high tide) elevation here is 7.0 feet relative to mean lower low water.  So these are pretty high water events.

Predicted (blue) and measured (red) water level at Port Angeles on 6 December 2017
So yesterday's predicted high water level for Port Angeles was 7.8 feet - thats pretty good - and i went down and snapped a pic looking east from the Feiro Marine Life Center (check it out above).  And I have to say, it was pretty unexciting.  What gives?  The measured water level yesterday was considerably lower than predicted...by a full foot.  So the actual water level actually was even lower than the daily high tide.

Predicted (blue), measured (green) and the difference between the two (purple) for Port Angeles for the last year
If we look back even further, and look at a whole year of water level data, we can see that, in fact, water level has reached that 7.5 ft threshold on numerous occasions.  The highest water level in the last year occurred on February 9 of this year.  This one was particularly cool because this particular event was the opposite of what happened yesterday.  It was an astronomical King Tide, with a predicted water level of 7.7 feet...but what actually hit the shoreline was an impressive actual water level of 9.2 feet...which is getting close to the highest observed water for this station (dating back to 1979) of 10.5 feet.  Sadly, no pictures.

Predicted (blue), and measured (green) water level in Port Angeles, WA, and the difference between the two (purple) for February 9, 2017
My take away, though, is that to really get the good King Tide photos its worthwhile looking watching your local tide gauge, and in particular paying attention to what we call the NTR, or "non-tidal residual", which is the difference between the observed and predicted water level (the purple lines on my plots).  If that NTR is high, like 1 ft plus in our area, then get out there!  Heck, if its really high (like 2+ ft), then get out there at any high tide.  

Tuesday, October 24, 2017

Sea Level Rise in the news

A history of long-term relative sea level change in Friday Harbor, Washington - a pattern that our data suggest is not due to land level change...but rather to the sea rising
Is it just me, or is sea level rise breaking through in our neck of the woods?  This week there were multiple articles making the rounds focused on sea level rise in Washington State including
reporting at the Seattle Times and KIRO7 on Zillow's updated sea level rise vulnerability assessment for real estate (which I will get to later) and Chris Dunagan's reporting for the Encyclopedia of Puget Sound on issues surrounding homeowner decision-making in the era of sea level rise and also his piece on SLR planning on Washington State.

Nuisance flooding like this, in Port Townsend on 10 March 2016, is almost certain to become more common and more of a problem in the future.  Photo courtesy of the Local 20/20 King Tides Team
The concept of climate-driven sea level change is nothing new...its been part of the climate change conversation for decades.  What is evolving is our understanding of the processes that drive sea level change (typically referred to as sea level components) over the community planning time-frames of interest.  The Earth system is complex, though, and the problem of interest here is complicated and multi-part:  How do emissions of greenhouse gases integrate with the natural cycles of those gases, how do the resulting concentrations influence the global heat budget, then how is extra heat distributed around and through the globe, and (finally) what are the process and rates at which that heat starts affect the components that lead to sea level rise (for example, how does that head lead to the break down of large masses of land-grounded ice on Antarctica)? 

Antarctica - a huge mass of land-grounded ice (this is an artists rendering of a cut-away view through the ice).  Its future matters to us.  Photo credit:  National Geographic
The evolving understanding of the processes that drive sea level change has led to an intense focus on this problem amongst the scientific community, as evidenced by the publication rate of papers focusing on sea level rise.  I used Web of Science to search for papers with the topics "sea level rise" and "climate change" and came up with this publication distribution through time:


This intense focus on the processes that drive sea level rise, of course, has led to a community planning problem, though; projections of sea level rise, or how much we can expect, change through time.  This isn't surprising if you think about it.  Projecting anything is hard.  As a society we make projections all the time in any number of fields...and many of them don't play out as expected.  In the case of sea level rise, projections will change as our understanding of processes driving sea level rise evolves, and also as we observe sea level rise happening and can compare those observations against projections.

This brings me back around to Zillow's analysis.  I like this approach that they took, where they used their national scope and data-analytics expertise to look at the possible national implications of sea level rise on their core product - homes.  Using a sea level rise of six feet relative to present, they found (perhaps not surprisingly) that places like Florida have a lot at stake.  It also is a reminder, though, that Washington State is not immune from sea level rise (even though we may be less vulnerable on a national scale) - there is a lot of high value infrastructure exposed.

Zillow has taken some criticism though, for the particular sea level they chose to do their analysis with - six feet relative to present sea level.  The Washington Policy Center published a blog, for example, saying that six feet was out of alignment with the most recently published projections by the IPCC.  An early statement in the article sets the tone, "Their projections are, essentially, made up".

Is six feet of sea level rise made up?  Does it "ignore the science", as the title of the Washington Policy Center piece implies?  No, quite the opposite, and here we simply see this problem associated with a rapidly advancing scientific endeavor.  The Zillow analysis uses a very recent NOAA assessment that attempts to assess the likelihood of different levels of sea level rise across the full range of uncertainty (using a very similar approach to what we are doing with the Washington Coastal Resilience Project).  By contrast, the IPCC projection plot shown in the Washington Policy Center blog only communicates a narrower "likely range", which the Washington Policy Center's blog misinterprets as communicating full range of uncertainty.  Zillow nicely acknowledges the uncertainty that the NOAA assessment is trying to communicate by stating, "if the oceans rise six feet – roughly midway between the high end of what the government says is “very likely” (4.3 feet) and the possibility of an 8-foot or greater rise that cannot be excluded." 

Lets dive a bit deeper here.  The "upper ends" of the probability distribution, where sea level rise exceeds the ~2-3 ft (by 2100) best estimate, are driven by places like Antarctica melting a lot more than was previously assumed in past sea level rise projections (ice sheet uncertainties, and their implications, are also touched on in this fascinating recent article by Forbes).  Science seems to be pointing towards these large masses of ice being more sensitive to climate change than has been previously assumed - a conclusion that, if it holds up, will lead to a greater likelihood of higer sea levels represented in future projections.  Its also worth acknowledging that, while 6 feet of sea level rise by 2100 may be unlikely based on NOAA's current assessment (and ours, for that matter), sea level isn't projected to fall in the coming centuries - and we become much more likely to get to 6 feet by, for example, 2150.

And, of course, Zillow could re-run their analysis with a best estimate of 3 feet, and we would still see vulnerabilities emerge, both around the country and in our own neck of the woods.  Despite changing projections, and uncertainty, we gain by planning now to avoid future costly problems.  

Tuesday, September 26, 2017

Real resilience?

















A home on the Strait of Juan de Fuca still on blocks after being moved back from the beach.  Photo taken 16 September 2017

 In my line of work we spend a good bit of time worrying about the future of existing coastal development, and how society will respond to the pressures of climate impacts like sea level rise. If you are a pessimist you sort of see the future being made of walls along the coast that keep the rising sea away from homes and infrastructure. Its not hard to see the point of these pessimists. Indeed there are entire countries that are built on the principle of defending land against the ocean (though that approach is changing).

 















The costs of defending Washington's extraordinary coastline would be huge

 The environmental costs, not to mention the dollar sums, of the defense approach to coastal hazards can be huge, and as a result my impression has always been that other alternatives may be feasible, and even preferable, here in Washington State. But guide stars for other approaches have been few and far between. Over the last year, though, I had the very special opportunity to work with a family trying to protect their waterfront home from chronic erosion and flooding. The day that I visited they were still recovering from a few harsh storm years that destroyed parts of their existing rip-rap armoring, and drove debris right up to their home:

 

 When I first interacted with them the family was considering some upgraded armoring - the defense approach. The costs, though, were huge for the design and construction of an upgraded defensive structure to protect their home, and I emphasized to them that no defensive structure is permanent...they all require maintenance. We then talked through other options, including moving their home out of harms way. Notably in this case this option appeared to be cheaper than defense, provided a longer-term solution AND would provide easier access to the beach (impaired at the time by the rip-rap, as seen below in a photo from 2016 looking up the beach):

 















I was impressed by the family's decision-making process, and was inspired by their decision to move their home and remove their existing armoring. Astonishingly, once the decision was made the process happened quickly - the home was moved and the rip-rap removed by August of this year. The home is now out of harm's way, the beach is in better condition from an ecological and aesthetic standpoint...at this stage it seems to me like the optimal decision was made in this case.  Hopefully there will be an opportunity in the future to get a better sense from those involved regarding the relative costs and benefits of the chosen approach.

The view on 16 September 2017 from nearly the same point as the photo above.  A low scarp is all that remains of the formerly defensive rip-rap structure

In my book, though, this is real resilience at work. The Friends of the San Juans recently put together a little video telling a similar story from Orcas Island:

 

 There are lots of things that came together in both of these cases. Notably the families' had both the means and the space to move their home. But in my mind that doesn't take away from how big these decisions are, or what they mean for our future. We often default to defense, but careful cost-benefit analysis isn't always done. Where it is, I see more and more occasions in which defense emerges as a less-than-ideal option.

Friday, September 8, 2017

Communicating the changing Elwha marine community - Part 1



My last post was on Elwha diving, and I don't want to give the impression that its all I do...but while I was away on vacation (and missing the final week of this summer's Elwha dives) Alison Morrow from King5 news joined Nancy, Steve and Marshall for a day out on the boat.  And out of that day came the nice little piece above.

And that made me realize...we are putting a lot of effort right now into synthesizing the reams of data we've collected across a variety of projects, and packaging our observations and what we've learned.  There will be more to come, but amongst the recent developments includes this USGS Youtube channel specifically dedicated to archiving our undersea diver-collected videos of the seafloor around the Elwha River delta.   We also expect, soon, a paper summarizing the major coastal ecological stories from the dam removal, and an interactive map that will allow a user to quickly move through space and time to explore coastal changes associated with the dam removal.  Stay tuned!

Thursday, August 10, 2017

Sites and sounds from this summer's return to the Elwha sea-floor


An embarrassment of tube worm riches, site E2, July 31 2017

Last week was our first week of diving for our annual (since 2008) sub-tidal site monitoring effort in the marine waters near the Elwha River Delta (i.e. here and here). Overall my take away is that the system "looks" very recovered relative to during the peak of dam removal in 2013 and 2014 (i.e. see the two comparative videos here). Here is a recent example, Site H2 in 2013, during dam removal. In particular in this video pay attention right at the outset to the turbidity visible in the water column, as well as the general lack of algae:



we returned to that site this summer, and here is the look see:



and now on to just a few highlights from this year:

Observed for the first time in our surveys, the orange peel nudibranch (Tochuina tetraquetra). This thing was big...probably 6-8 inches in length...



fan hydroids



We work out of the US Coast Guard Base on Ediz Hook, and this massive ball of herring was at the dock the entire week



The world's largest barnacle, Balanus nubilus, at work


Observed at Site C1, something we used to see a bit before dam removal...a Bull Kelp (Nereocystis leutkeana) growing attached to a tubeworm (in this case Spiochaetopterus sp.). Typically Bull Kelp will attach to bedrock, boulders or large cobble.