Finding the sand from the Elwha River

I've posted recently about the sand that is accreting to the beach near the river mouth of the Elwha River. I and others are tracking this carefully to determine if and when the removal of two dams on the river acts to halt or reverses chronic erosion along the delta. Last week I also went out for the first in a series of dive sessions, with other divers from the USGS, the Lower Elwha Klallam Tribe and the EPA, to monitor a series of sub-tidal sites near the Elwha River mouth (the red dots in the photo below):

At each site we are collecting a suite of data to describe the invertebrate and kelp community, as well as the substrate. We started this project in 2008, and more information on the project and the biological community off-shore of the Elwha can be found here.

The new sand on the beach made me think that we might see some new sand at some of our sites, especially the shallow sites to the east of the river mouth. But I was struck by how similar everything looked (as reported by the Peninsula Daily News), from a grain-size standpoint, to our surveys from the previous year. So we went hunting for it...

We decided to enter the water at our monitoring site "D1" and swim a transect to the river mouth along a line that is surveyed at least once a year by the USGS for bathymetry:

Preliminary results from the most recent USGS bathymetry survey, in May 2012, suggest that there had been new sediment added to this transect between September 2011 and May 2012:

This is a series of profiles collected along the transect since 2005 (courtesy of Andrew Stevens, USGS), showing the transition of this particular slice of the earth from a beach to a river mouth (between about 2005 and 2008), and the subsequent accumulation of sediment in the shallow coastal zone (since 2008). Between September 2011 and May 2012 there was more sediment added...and I wanted to know what its composition was...sand? sand and gravel? mud?

The video that we collected gives it away. I shot video at various depths as we moved up the slope towards the river mouth. Each of these video segments is prefaced by showing the profile again, with a black arrow that corresponds to our position on the profile. Enjoy!

Recent Article in the PDN on the Elwha

I love my local paper. I am a loyal subscriber, and have no plans on ever changing that. In an age defined in part, we are told, by dying print media, I want to do everything I can to keep the Peninsula Daily News chugging along.

That being said, I have been known to criticize the PDN when it comes to reporting on the sorts of coastal scientific issues that I am most familiar with (see my blog post titled "Where Do They Get This Stuff From?" from last December).

But I'm overall pretty pleased with Arwyn Rice's article from yesterday, "Researchers Excited By Early Signs of Elwha Changes" and thought that she did a good job trying to capture what I was trying to say, representing the uncertainty in our science, and forming it into a decent summary.

That being said, lets move on to the errata. First, when Arwyn writes that "Once a sandy beach existed just east of the Elwha River mouth" the implication is that I said that. I didn't. In fact, there is virtually no evidence that this was the case. Really the only data that I've seen suggesting what the grain size on the beach was like prior to the dams comes from an 1908 Coast Survey chart, which marks the shoreline near the mouth as "Sand and Pebbles"...suggesting the possibility that it was sort of like what we see now.

Next, Rice quoted me as saying "In the past 15 to 20 years, erosion has taken 12 feet per year". If I did say that, I am sorry. What I should have said is "erosion has taken UP TO 12 feet per year on average". Erosion in places and over some time periods has exceeded that rate, and in others it is less. Erosion is like that.

Also, as I've written in the past, i am not yet willing to say that the removal of the Elwha dams will "rebuild Ediz Hook". To be fair this statement wasn't attributed to me in Arwyn's article, but it may be interpreted as such by association. I'm not ever sure that Ediz Hook needs "rebuilding" so much as a different perspective on how we manage it. But that is a complicated story, one that needs some study, and is definitely for a different time.

Not quite sure where this came from, "The amount of sediment to be deposited from the dam removal is the equivalent of a 100-year or 500-year event, he said." I think that one is mis-attributed since we didn't really talk about sediment quantities observed at the mouth, and I wouldn't have had much to say there anyway, since we don't yet have good data on that topic.

And finally, and really digging into the weeds, I can see why Arwyn wrote, "Once Lake Mills is removed, the river's sediment load will increase dramatically, he said." since we talked about how a larger fraction of the stored sediment in the Elwha system is still stuck in Lake Mills. But the term "load" is some circle suggests that the amount of sediment that the river is carrying at one point in time, versus the long-term delivery to where I care about it - the mouth and coastal zone. The instantaneous load may or may not increase when Glines comes out(it will probably depend more on river flow than anything), but certainly the amount of sediment available for transport down the river will increase.

Boat-based LiDAR to measure bluff erosion

The shoreline of the Strait of Juan de Fuca, like much of Puget Sound and even some of the outer coast of Washington, is a strip of tall and very actively eroding bluffs. These bluffs, built primarily of loose sediment deposited by retreating glaciers >15,000 years ago, are the subject of considerable interest in the management of marine resources in our area. Despite being fairly easily eroded, their edges seem to be preferred places to build homes. Great views, indeed, but over even relatively shore time periods - 10 or 20 years - these bluffs can move shoreward due to erosion many 10's of feet. In most cases regionally and around the country, their have been two inevitable outcomes: 1) Either homes are lost to the sea, or 2) the bluff is "armored" in some way to reduce or stop erosion. This engineering solution, while attractive at first glance, carries a hidden cost - the sediment eroded from the bluffs deposits on the beach at the base of the bluff, where it can contribute (via processes that we are only just starting to understand) to building habitat. In some cases, the connection between bluff erosion and habitat-building processes seems stunningly clear; Dungeness Spit, widely considered a regional gem in terms of coastal habitat, is probably maintained almost purely by the erosion of soft bluffs to the west.

The WA DOE research vessel R/V George Davison (in the far field, right) scans the bluffs immediately east of the Elwha River delta

Despite the apparent importance of these bluffs to shallow marine habitats, our understanding of how they erode, and how much they erode, is surprisingly naive. Most of the work that has been done to quantify rates of erosion around Puget Sound and in the Strait of Juan de Fuca was/is done by drawing lines on aerial photos taken at various times over the last century or so. This was state-of-the-are even 20 years ago, but there are a lot of uncertainties when making measurements off of photos - how good is the photo? Does vegetation block the view of the bluff edge? Does the line actually represent the bluff face, or is the bluff face overhung? Also, it is very difficult to quantify the volume of sediment contributed to the beach from aerial photos.

A ground control marker on the bluff west of Port Angeles

As a result, new techniques are warranted. Over the last 10 years or so there has been an jump forward in remote sensing technologies, including Light Detection and Ranging (LiDAR), which uses a laser fired from a scanner to very rapidly estimate the distance to a surface some distance away. Associated with a high-precision GPS unit, and a device called an inertial motion unit, it is now possible to very quickly collect hundreds of thousands of discrete measurements of a surface from a moving vehicle. This has been done from planes for a good two decades or more, but planes aren't the best platform to measure bluffs from, since the bluff face is oriented up and down relative to the plane. Last week, for the first time, bluffs in the Strait of Juan de Fuca were scanned from a LiDAR unit mounted on a boat. Using a boat, large distances of bluff can be scanned fairly quickly (miles of bluff per day).

Diana McCandless, WA DOE, surveys a ground control point on the beach east of the Elwha River delta

These bluff erosion measurements are led by the WA DOE Coastal Monitoring and Analysis Program, with support from WA Sea Grant and WA DNR. My role in this project was to help with local logistics and help set-up ground control points - large targets visible on the boat that can be used to assess how well the LiDAR scanner is measuring the surface. Our goal is to measure bluff erosion as a volume (i.e. so many cubic feet of sediment were eroded from the bluff over x number of years), and so the ground control points allow us to add error bars to that estimate. The first survey was a huge success - a least logistically. We had phenomenal support from private and public land-owners all over the county. And this bluff measurement project isn't even the whole story...it is just a part of a larger project coordinated by the Coastal Watershed Institute, with involvement by Clallam County and Earth Economics, as well as a whole suite of supporters.

A reminder - we face other coastal hazards...

This photo was taken by Dr. Sarah Sterling a few weeks back in a salt marsh west of Port Angeles. The sand layers at inch 26 and inch 28.5 on the ruler are unequivocally related to tsunamis, which push marine sands up into the salt marsh. Nearly identical sand layers are found in Discovery Bay, east of Port Angeles. The layers shown here are probably from tsunamis that happened hundreds of years ago. The scale of these layers suggest a pretty substantial tsunami that may be associated with a rupture along the Cascadia subduction zone, just 50 miles off of our coast. Seeing these layers was a reminder to me that someday - perhaps sooner, or perhaps later - we (the Olympic Peninsula) are going to experience another of these big earthquakes and/or tsunami. And the evidence from this photo and from Discovery Bay suggests that tsunamis here can be of a scale to powerfully affect the entire shoreline of the Strait of Juan de Fuca. I bring this up as a reminder - the news is filled these days with hand-wringing and nail-biting regarding the landfall of debris from the March 2011 Tohoku tsunami on our shores. Tsunami debris is a hazard, no doubt. Pile enough plastic on the beach and bad things happen. Enough of it in the water probably poses a toxicity risk, not to mention endangering wildlife and even creating navigation hazards. But I find that I cannot wholeheartedly agree with Chris Pallister, who runs an organization dedicated towards cleaning debris from the shores of Prince William Sound, who was quoted in an article today saying, "I think this is far worse than any oil spill that we've ever faced on the West Coast or any other environmental disaster we've faced on the West Coast". That statement ignores the environmental problems associated with the huge volumes of marine debris that enter the ocean EACH YEAR (far more plastic debris is probably released into the ocean as non-point pollution than from the Tohoku tsunami)and also downplays the devastation associated with large oil spills. The statement also seems to downplay the risk that we face from seismic events and tsunami, and I can't even give Chris the benefit of the doubt and assume that he is talking about events only in recent memory. Its only been 48 short years since an earthquake and tsunami wrecked SE Alaska, killing 119 people in the process. The calls for greater preparedness for the tsunami debris are warranted. We will have to put our collective shoulder to the wheel to get beaches cleaned up, and some intervention by state and federal government may be necessary to deal with big items, toxic material or invasive species. But those loud calls, in my humble opinion, should be accompanied by, and I would argue overshadowed by, louder calls for better preparation for a local seismic event and tsunami...

The Changing Elwha shoreline

While the removal of the Elwha dams is not yet complete, we are already getting a taste of the potential restoration benefit and scale of this project. Starting a few months ago we started to see sand on the beach in places where we never had before. Every few weeks I head down to the Elwha delta and measure a beach profile and collect grain size imagery at 3-4 set monitoring locations (the ones in red in the photo below): On 24 April 2012 I put together a little summary based on some observations of NEW sand, tentatively attributed to the dam removal, at one of three sites that I monitor every few weeks. This is from Line 164, just to the east of the river mouth, and you are looking at a profile collected on three different dates, plus some grain size photos and oblique photos of the beach: This sand accretion was relatively high up on the profile, around 0.5m (1.5 feet or so) above MLLW. While very cool (this was, after all, some of the first sand that I could attribute to the dam removal that I observed on the beach), the amount of sand, and its extent along the beach, were both pretty minor. Now, though, the lower tides of May and June have given us a better view of sand accretion lower down on the profile - and it turns out that this is where a lot of the action is. Right around the river mouth there is a substantial body of sand that I first observed at the beginning of May: (Sorry about the wind and bad audio in this vid). At the time it wasn't clear if this sand would persist, or if it was a temporary blip in a longer-term reconfiguration of the Elwha delta in response to the addition of new sediment from the dam removal. It now appears, though, that the various sand bodies are growing and seem to be set to stay. For example, this set of profiles from today, and 5 July 2011 (about a year ago), suggests there has been substantial profile accretion below about 0 MLLW (where the black line, representing the surface today, is well above the gray line, representing the surface in July 2011): and the grain size shift associated with that accretion is readily apparent in these "before and after" photos taken at an elevation of -0.15 m MLLW at line 164 on 5 July 2011 and today: I was also surprised to find that the fine sand depositing down low on the beach extends far to the east. At Line 204 the profile was covered with fine sand below a depth of about -0.25 m MLLW, as you can see in this series of photos taken at 0.25 m elevation increments starting at -1.00 m MLLW: While I don't have any grain size photos from earlier dates to compare to for this relatively low part of the profile (today's low tide was exceptionally low - I don't often get the opportunity to sample below MLLW), my own observations after 5 years of work out there suggests that this sand is NEW. While the upper beach itself looks about like it always has around most of the delta, at line 164 that small sand body that I originally reported on at the end of April (see above) seems to have grown and has now welded to the base of the foreshore. Here you can see a photo taken from low on the profile looking towards the shore, with a bar of sand that has attached to the upper part of the beach. Comparing profiles from today and two weeks ago (May 20), that profile growth is very clear...all sand. This observations is particularly interesting in light of one of my major motivations for doing this - this beach is seriously erosive, and I am interested in "if, how and when" the sediment associated with the dam removal may act to reverse the chronic erosion that causes all sorts of problems on the delta. This sand accreting to the foreshore is some of the first evidence that the upper part of the profile, which is the part that erodes so rapidly, might enjoy some sort of restoration benefit from the dam removal...very cool stuff. Thanks to colleagues at the US Geological Survey and the Lower Elwha Klallam Tribe for helping to collect and interpret some of the data you see here...

Time Lapse of the Elwha

Its been a while since my last post - as the field season ramps up time in the office has been squeezed. But as the days lengthen and we get more sun the conditions for photography improve, and the imagery coming in from our time-lapse cameras pointing at the Elwha delta are really nice. This on-going effort is designed to further our understanding of the dynamics of the Elwha River plume and to track gross changes to the morphology of the river mouth. This last series that came in from Fox Point is really nice - the plume is mesmerizing as it swings back and forth under the influence of tidal currents. The lower tides at the end of this series (early May) also show some of the morphologic changes we are seeing at the river mouth...

Olympic Coast Clean-up

A 4:45 am wake up is nothing to be trifled with, and I loathed it as the alarm popped off this morning. But even in my morning haze I had to admit that I was a bit excited. From 2003-2006, when I worked for the Surfrider Foundation, I worked every year to pull off the Olympic Coast clean-up, and this morning I woke up and headed out to the coast for this year's event, my first since those SF days. Along with a group from ONP and The Surfrider Foundation's South Sound Chapter I manned the registration booth handling Rialto Beach (including the cove north of hole-in-the-wall), First Beach, Second Beach and Third Beach. While I am as in to cleaning beaches as the next person I had a secondary goal - use the observations of the 100+ people volunteering their time to examine two questions: First, can we use the data collected during the clean-up to identify "collector" beaches - places that, because of the vagaries of wave hydrodynamics or nearhshore currents collect relatively more stuff than other beaches. There is great interest on the outer coast in this question because of its potential importance in planning for an oil spill. Next, given the volume of reports coming in that seem to suggest the arrival of significant quantities of tsunami-related debris on our coast, I was interested to observe the debris pulled off of these beaches - would we see more than we have in the past? Would we see a lot of debris with Japan? Note: Check out this article about some of the first CONFIRMED beach debris from the tsunami in Alaska. First questions first. In talking to volunteers as they returned it immediately became clear that, of the beaches considered, Second Beach seemed a good candidate to be a "collector". Multiple volunteers talked about coming upon significant collections of trash, and one party described spending two hours on a 200' section of beach. I wanted to take this further. Each volunteer collects data as they clean the beach, and I was able to quickly enter a few key bits: How many people in their party, how many hours they were on the beach, and their estimate of the weight of debris removed from the beach. Using this data I was able to estimate the total weight removed from a particular beach during the day, the total effort on the beach (in person-hours) and I then was able to measure the total length of the beach from Google Earth. This allowed me to calculate a metric that, while, rough, provides some estimate of the debris removed from the beach for a give effort and distance. I think of it as the beaches "debris production". And, using the magic of Excel for quick plotting, voila...

Shown here are mean production rates, by party, with the error bars showing the standard error of that mean. The pattern suggests that, indeed, Second Beach may have a higher debris production than Rialto (though its not a significant difference). Third Beach looks higher, but I had only one sample for that beach - one party that reported their information to me, so that number should be considered suspect since there was, not unsurprisingly, lots of variability between parties. And we didn't end up with any parties on First Beach today since it was cleaned yesterday, so I couldn't include it. But in the end I like the method - and we may actually be able to discern some meaningful patterns if we can do this analysis on clean-up data going back to 2003... On to question two - I had sort of a vague hypothesis going into today - that if the reports of buoys and other large floaty objects washing up on our coast were from the tsunami, that it might be reasonable to suspect that other relatively floaty things - particularly bottles, would be found as well in relatively large numbers. In other words, we might expect to see a disproportionate number of plastic bottles collected from the beach from Japan, as compared to other locations. At the end of the day we had a flat bed truck full of bags of bottles sorted for recycling - there was my sample - and I spent about an hour going through it.

Certainly we found objects that we tentatively sourced to japan based on visible script (particularly buoys and bottles). I didn't have the time for real quantification (though such a project would be very useful) and was forced into some broad estimation, but my guess is that about 25% of the bottles were definitely from asia, 25% appeared to be local (i.e. from the U.S. and probably either from land-based sources or nearshore boats) and about 50% had no discernible markings, making it impossible to determine their source. As an aside, a few were particularly interesting. We suspect that these two were from the Middle East and Russia, respectively:

But back to Japan...of the 25% of the bottles that I had some confidence were from asia I could positively identify some bottles from Malaysia, Singapore, Hong Kong and the Phillipines, usually based on a bit of English here and there, or in some cases, like this bottle from Hong Kong, from the country code on the URL on the label:

Other bottles we tentatively sourced to China and Japan based on the script (noting, however, that none of us had ever studied those languages). Here are a few examples of those:

Notably, though, of all of those bottles from Asia (an estimated 25% of the total) there didn't seem to be any type or script that was dominant. Additionally, there seemed to be no more bottles, or debris in general (based on my recollection), than in any other clean up year that I've been involved with. Other debris patterns also didn't point to a significant load (i.e. outside the normal baseline) from Japan. We were given a set of photos of buoys tentatively associated with the tsunami debris, which all volunteers were asked to look for and track separately. Of the buoy types that we were asked to identify (6 of them) we did find some, including two of the rabbit ear type:

and at least 1 of a big round polysterene type that you can see in the back right corner of the flatbed truck in the photo above. We also found two large containers that looked vaguely like types associated with Japan, but they were blue and of a different configuration than the ones in the photos we were provided:

This is all just observational evidence, and certainly not a proper test of the hypothesis above. But again, given some of the accounts that I've heard, part of me was expecting a fairly significant debris signal from Japan already, and I don't feel that we saw that at all. Not a surprise I suppose, models suggest the bulk of it will arrive later this year at the earliest...but some of the comments and observations I've heard of late have led me to believe that observers were seeing a lot of items on the beach already from the tsunami. We certainly can't say that we saw that today. As an aside, if anyone does read Japanese or Chinese, I can send the photos I took today of bottles - it would be interesting to confirm their source. Email me at immiller@u.washington.edu