The notion of putting beaches back together in circumstances where they have been lost (either due to erosion, armoring, or filling of intertidal habitat) is not a new one. There are countless case studies on-line describing some truly giant beach nourishment projects, and the Program for the Study of the Developed Shoreline at Western Caroline University maintains a nice interactive database of projects in the U.S. One thing that is notable from this database, though, is that beach nourishment on the west coast, and in Washington in particular, is still a relatively rare and small-scale thing...not absent, but not utilized here at the scale that it has been applied elsewhere - particularly on the east and Gulf coasts. As Hugh Shipman notes, though, we are seeing more and more of these sorts of "beach building" projects in our area...and with the increasing emphasis on coastal restoration, combined with the pressure that communities are going to face in the coming decades due to sea level rise, it is likely that we will see many more.
This weekend I had the chance to check out the newly engineered beach in Boulevard Park in Bellingham Bay. This is a popular and heavily used park in Bellingham, with a shoreline that had been composed primarily of various sorts of rock, concrete, tires and piling to protect the shoreline. Designed by Coastal Geologic Services, the new beach is clearly designed to stay in place while providing new aesthetic, recreational and, possibly, ecological value to a highly altered shoreline. Anyhow, here is the site as it looks now:
I was definitely struck by how popular this little section of new beach was, despite being composed of a fairly coarse substrate. It has a small groin to the north to, I presume, trap sediment in transport due to the powerful south winds that sweep into Bellingham Bay in the winter. One process that was definitely in play when I visited - strong offshore transport of sediment due to numerous rock throwers...the grain size utilized is the perfect throwing size!
A juvenile Dungeness Crab utilizing the new sand accreting to the lower profile at Line 204...the first real indication from our surveys that this material is being used as habitat...
Fall is an exciting time for Pacific Northwest rivers, since this is the time period when we start to see opportunities for really high flows. For the Elwha River in particular many of us are pretty addicted to watching the flow of the river since, in general, the big morphologic changes in the river and coastal zone tend to correspond to these flow events. And this year it came early, on September 28th, with the flow gauge at MacDonald Bridge recording what was likely the largest flow since dam removal started:
Based on previous work it seems likely that this flow delivered a substantial volume of new sediment to the coastal zone, but much of it is probably below the water's surface. I started getting questions almost immediately, though, regarding whether we were seeing any changes on the beach due to this river flow. The answer...possibly? In the time lapse video below, for example, you can see some large wood moving on to the river mouth during the high flow period (28-30 September or so). Its not totally clear to me from the time lapse that the morphology of the river mouth changed substantially during that flow, though...
Beach surveys on 4 October and 7 October do show some interesting changes to the beach...but whether these are linked directly to the Sept 28th high flow isn't clear. In the figure below I present data from the four transects that I monitor once or twice a month, collecting a profile and grain size photos at each site. Across the top are the profiles from my last three surveys at each site, and I've circle some of the interesting developments at each site. At lower right in the figure is a time-series of the position of the beach on the transect...so if the line is pointing downward that suggests erosion, whereas a move into the positive scale on the y-axis suggests beach growth.
Interestingly enough, the beach at line 132 has seen some of the most obvious change over the last few months of summer, at least in terms of changes high up on the beach face (#1 in the figure above). In this case I've circled accretion of a storm berm over the last month, composed of sand. This part of the profile at this site is typically very coarse - this grain size photo from 3.50 m elevation at Line 132 from 6 August 2013 photo is representative:
but can be compared to the photo from the same profile and elevation collected on 4 October 2013:
At Line 164 I've circled an area of new accretion (#2 in the figure above). This is a place where the high flow in September may have made a difference, since the river channel now runs along and truncates that profile. So that accretion that I've circled appears to be, effectively, a bank of the river. During our survey on 7 October we were unable to cross the channel at this point, and could not extend the profile.
At Line 190 the big story is what appears to be a very slight inflation of the profile on the high intertidal beach. If you track Line 190 in the time series of beach position at lower right you can see that this beach has eroded dramatically over the last two years...so to see even a hint of profile accretion is something. Interestingly enough, though, the grain size photos suggest that the beach at this elevation is still very coarse:
so its not totally clear what is going on here.
Finally, the news from my most eastward profile is continued accretion of sand in the low intertidal (#4 in the figure above). This is all medium sand that appears to be transporting on-shore from a deposit in shallow water just off-shore. This brings me, though, to the most exciting observation from my shoreline survey week...the first observed utilization of sand on the lower profile as habitat. We found a Dungeness Crab snuggled up in the sand waiting out the low tide at about the 0.5 m elevation on Line 204 (see photo at top of this post). This is a site that, one year ago would have looked like this:
and probably wouldn't have been viewed as attractive by Dungeness Crab. Now, though, it appears to fit the bill.
Thank you to Karsten Turrey for assisting with the 7 October 2013 beach survey...
Dams have two big consequences in rivers, and I usually focus on just one of them - the blocked DOWNstream flow of sediment. But yesterday I had the opportunity to go out to the river and observe the UPstream flow of fish in the newly opened middle reach of the Elwha River. This is the reach between the two dams:
This isn't a new thing - fish spawned in the middle reach last summer, but the river is flowing clear again in the middle reach, which makes for some very nice bank-side viewing conditions:
Okay, enough of the UPstream flow...but lets stay away from dirt for at least one more post. How about the downstream flow of paddlers through the newly opened Aldwell dam site (video by John Gussman):
And since we are on the topic of John Gussman, he sent along this nice perspective on change in the river itself, looking downstream from the Altair Bridge:
Site 7SS1 off of Green Point in the Strait of Juan de Fuca
As part of this year's effort we re-surveyed a variety of sites that we hadn't visited since 2009, including a site called 7SS1 just to the east of Green Point. This site was one of the locations that first led me to sit up and take notice of these benthic amphipods because they absolutely cover the seafloor
A shot of the seafloor at site 7SS1...each of those things is an Ampelisca tube
This time around I decided to do a quick and dirty estimate of the density of these amphipods at this site by collecting a single sample (in this case using a 6 inch diameter tube pressed into the seafloor). I then sieved and hand sampled the amphipods out of that bulk sample, counted the individuals then dried the entire sample (in my home oven...much to my family's chagrin) and weighed the dried sample.
the mass of amphipods pulled out of the sediment sample from 7SS1, a total of 613 individuals
When all was said and done the numbers were astonishing...613 amphipods (and I think I did pretty well here, plus or minus maybe 10% on the count) in the sample, which equates to ~36,000 amphipods per square meter. The dry mass of the sample came out to 5.8 g, which equates to ~340 grams per square meter - or the equivalent of about two or three quarter-pounders with cheese. In 2009 we observed bite scars at this site that we attributed to gray whale feeding:
A divot in the seafloor, observed in 2009, that we attributed to Grey Whale feeding
A Grey Whale observed on the surface near site 7SS1 in 2008
Ampelisca seem to require particular grain sizes to build their tubes, and the hypothesis we presented in the report call-out wondered if the dam removal may make particular grain sizes more available to these amphipods and promote their recruitment in the Elwha coastal zone (where they are relatively infrequent)...still watching on that one.
A red sea urchin (Stronglyocentrotus franciscanus) with a transect survey tape draped over it, at a site off of the Elwha River mouth)
Coastal resilience is not just about the physical interactions (erosion, flooding, tsunami) between the ocean and coastal communities. The concept also includes ecosystems, and the ability of coastal ecosystems (which support coastal communities) to respond to changes. In that vein, I've continued with a project I helped to initiate while a graduate student at UCSC designed to assess how the Elwha dam removal will change or affect the marine biological community that lives in the coastal zone adjacent to the Elwha River delta. Originally a USGS project, our team is now a nice example of multi-agency collaboration, with contributions from USGS, the Lower Elwha Klallam Tribe, WA Sea Grant, EPA and the US Coast Guard. We've just wrapped up our second of three sessions this summer, working to collect data on the fish, invertebrate and algae community at >20 sites at the Elwha and two reference areas (Green Point and Low Point). We also deploy and recover sensors logging temperature and light data, and measure information on the substrate.
There are a few interesting observations from the summer. We've been astonished by the recruitment of juvenile Dungeness Crab (Metacarcinus magister) at many of our sites. Check this video from a site near the base of Ediz Hook:
Our data set really isn't effective at detecting changes in these sorts of mobile and patchy species over time, but we can say that we've never seen anything like this before at our sites. Does it somehow have something to do with the removal? With ocean conditions? Pretty intriguing...
Next, we've hypothesized that the seafloor along parts of the shallow nearshore of the Elwha coastal zone would see substrate transitions as sediment from the Elwha River mouth enters the coastal environment. Furthermore, we expect that new habitats and biological communities would develop in these areas. At most sites, though, (outside of those sites that are more or less right in the river mouth) we haven't yet detected a dramatic shift in the substrate (from gravel to sand, for example)...but there is now at least one notable exception. At a site in shallow water (~25 feet) about 500 yards to the east of the river mouth we've tracked the arrival of sand from the river, which now entirely covers the seafloor. This video, for example, was shot in September of 2009:
That seem piece of sea-floor now looks like this:
We've been able to constrain the timing of the arrival of this sand to the last two months. Now, in the years ahead, our goal will be to assess if this material sticks around, and if and how a different biological community takes shape in these areas.
The way in...literally and metaphorically for many students!
No, not Orcinus orca...the Ocean Research College Academy, an Everett Community College-based program and creation of director (and biologist, mentor, educator, USCG certified captain, grant-writer, development specialist...the list goes on and on) Ardi Kveven. I met Ardi at the ASLO conference in New Orleans in 2013, and was stunned that I hadn't heard of her program before. They use a cohort approach, serving running start students at Everett Community college with ocean sciences as the unifying concept behind core learning in English, Math, Science, History, etc. The students take part in monthly (give or take) cruises in Possession Sound and, at this point (~10 years in) have an astonishing long term data set, not to mention a track record of student success.
I definitely got what I came for - I'm impressed. I had a great day talking to students, watching them deploy instruments, manage data and samples, and describe their processes to me. A few more photos of the day:
pre-cruise prep in the lab
ORCA's location in the Everett Marina makes the trip to the research vessel a breeze - a 5 minute walk
pre-cruise briefing
Students from ORCA prepare to deploy instruments off of the bow of the Hat Island ferry
