Monday, August 17, 2015

Mt St Helens

Visited Mt St Helens for the first time in at least 20 years last week during a week-long vacation with my family. While the focus was checking out a volcano with a trio of young boys, I couldn't help but marvel at how important the mountain, and its eruption in May 1980, has been to how we view perceive, study, and prepare for natural hazards.

We spent the entirety of our two days on the north side of the volcano, in the areas directly affected by the massive landslide that preceded the blast, the pyroclastic flow that characterized the eruption itself, and the lahar that swept down the Toutle River in the hours after the eruption, and visited both the Johnston Ridge Observatory and Weyerhauser's Forest Learning Center. The Forest Learning Center, in particular, was a surprise hit for both its diverse and innovative interpretive materials, and its awesome playground (which Theodore found particularly appealing):

Our first stop, though, was the buried A-frame alongside the Toutle River, some 25 miles downstream from the volcano. While this place is, at its heart, a classic American road-side also really helps to transport you back to mid-day during the eruption, when mud enveloped the entire floodplain:

McHenry and my nephew Silas staring into the second floor window of a house buried by the lahar that followed the eruption

Part and parcel of the story of the Toutle Valley lahar was getting to view and grapple with the management implications of the massive quantity of sediment injected into lowland watersheds during the eruption. The management of that sediment is an on-going issue, and includes a dam purpose built to retain sediment in the upper Toutle River valley. Here is a view looking downstream along the Toutle Valley:

The Toutle was transformed by the massive dump of sediment from the eruption, and its floodplain, 35 years later, still gives every appearance of trying to work through the massive sediment supply. It is generally poorly vegetated, highly braided, and very broad.

Up at the volcano itself, the geology is absorbing. We walked the Hummocks Trail through the landslide area just down valley from the mountain, through giant piles of debris, most of it composed of angular chunks of the mountain itself.

An angular rock carried down valley by the massive landslide that preceded the eruption, as the whole north flank of the mountain collapsed.

One of the hummocks, huge piles of dust, angular boulders, and ash, associated with the massive landslide that came off of Mt St Helens on the morning of May 18

However, I found myself focusing on the stories that provided insight into how people at that time viewed and responded to the risk of an eruption. Some of the interpretive materials at the Johnston Ridge Observatory and the Forest Science Center really helped me to understand how difficult the days leading up to the eruption were for scientists, local and state decision-makers, and emergency managers. The scale of the devastation, even 35 years later, makes it hard to believe that many doubted the advice provided by scientists working on the project...but some died as a result of that doubt.

Indicators of destruction: The remnants of trees at Johnston Ridge, ripped from their stumps

Those that died. Front and center is the name of David Johnston, a USGS scientist that died in the line of duty during the eruption, manning a volcano observation post, on what is now called Johnston Ridge. The landslide that preceded the eruption swept over this ridge within seconds of it breaking loose from the flank of Mt St Helens.

Monday, July 20, 2015

Short-term beach change on Dungeness Spit

The study site - approximately Mile 3 on Dungeness Spit. This view is looking north-east towards the light house.

Our beaches are extraordinarily dynamic, and as I go about doing the work that I do I hear countless stories about big changes to the morphology of beaches that happen over very short time-scales. I don't always get the chance to really address that kind of variability since most of my shoreline monitoring sites are typically re-occupied only once or twice a year. Two of my sites, though, are unique. Both Ediz Hook and Dungeness Spit take two tidal cycles to finish, and so for this year's Dungeness Spit survey I collected some data on both of my survey days (8 June and 1 July) along an area around the 3 mile mark on the spit in order to assess how much change occurred over that time period. The conclusion - more than you might expect for a few relatively calm weeks in the summer.

Lets start with the profile data from three transects. In all cases change is occurring below Mean High Water (MHW). Here is the most landward one first:

Here is appears that the beach has accreted, or grown over that two week period, over almost the entire profile below MHW. Interestingly, though, this accretion doesn't appear to dramatically change the grain size composition of the beach face. Here is an example photo taken at 1 meter above MLLW on 8 June:

and then another taken at the same elevation on 1 July, after beach accretion:

Here is another example from lower down on the beach (at Mean Lower Low Water) that does suggest a sandier substrate associated with the accretion suggested by the profile data. First the photo from 8 June:

and then here is the photo from 1 July, again shot at MLLW:

Moving to the next transect to the northeast, the patterns was reversed, with the profile data suggesting erosion on the lower part of the beach over the three week period:

and finally the next transect to the east (and the last that I overlapped) suggests a bit of a mix of erosion on the lower part of the beach, and some accretion on the upper beach (around 3m):

This seems to be supported by oblique photos collected at that site. Here is the one from 8 June:

and if you compare that carefully to the oblique from 1 July:

you will note the addition of some large woody debris high up on the profile, which is often associated with beach accretion.

What were the factors that conspired to drive these changes? Thats a tough one, but we can be sure that, despite it being summer, there was plenty of energy delivered to the beach. Here is a summary of water level data (bottom panel, from Port Angeles, referenced to MHW) along with significant wave height and dominant wave period from the Hein Bank buoy:

In particular the early part of the period, between maybe June 10 and June 19, was characterized by pretty high water (0.5 m or so above MHW during the high tides), and multiple occurrences of waves with heights > 1 m. The high correlation between the average wind speed (middle panel), and wave heights suggest that these are primarily locally generated wind waves rather than swell energy from ocean - not at all surprising for the summer season in the Strait of Juan de Fuca (see Chapter 3 in my dissertation for a description of seasonal wave patterns from Elwha). If I had to guess, I would think that those profile changes, at least on the upper profile (above MHW) on the last transect, happened in that time period.

Tuesday, June 9, 2015

Back out to the Spit

The view from the end of Dungeness Spit

For the third year I was able to arrange with the US Fish and Wildlife Service to collect beach morphology data on Dungeness Spit for my shoreline monitoring program. This is such a special survey to me - its the most difficult logistically, but provides a chance to collect some data on what is really a spectacular coastal feature:

A view of the lighthouse from the end of the Spit, with the Olympics in the background.

Spits are really such important coastal features. In the case of Dungeness Spit it creates a very unique and productive shallow water habitat in its lee. And its "sister", Ediz Hook, creates what many argue is the best harbor in the region. In my view, we simply need to do a better job at understanding what makes these sorts of coastal features work. One surprise, at least based off looking at the preliminary data, is that the end of the Spit appears to have retreated a bit, at least over the last few years:

Again, these data are very preliminary, and just one profile doesn't tell the whole story...but given the average rates of growth reported by Maury Schwartz this is an interesting finding. Part of the story could be related to the migration of the top of the Spit, but it clearly is a complicated story. These profiles cutting through the bulge at the end of the spit for example, suggest the possibility (again, using the caveat that just one set of profiles per year doesn't a convincing story make) that erosion on the seaward side of the spit was associated with accretion on the landward side between 2012-2014:

But that pattern didn't hold up in 2015.

More to come - I will head out to finish the long skinny part of the Spit later this month or next, and then hopefully continue annual surveys for at least another two years.

Wednesday, May 27, 2015

Getting nerdy with sea level in the Pacific Northwest

A few weeks back I gave the webinar above on a new approach we are using to project future sea level in a climate change adaptation planning project I am involved in focusing on Clallam and Jefferson Counties in Washington State. The approach takes advantage of a new synthesis of sea level rise projections published last year.

Despite struggling with how to most effectively communicate probabilistic sea level rise projections, I'm really liking this new approach, and its got me thinking about how to do an even better job of incorporating and communicating the current and future hazard related to sea level processes. In the webinar, though, I highlight a few outstanding needs - gaps in research or data needs that are limiting our ability to be as rigorous we can possibly be with assessing contemporary and future hazards related to sea level and coastal impacts.

As an example, consider that these sea level rise projections are meant to get at the "still water level" (i.e. ignoring waves). In general we've viewed that as an okay first-order approximation of the hazard in the inland waters of Washington State...but is it?

First consider the photo above, which comes from Cliff Mass's Weather Blog (check out the specific blog here), but that he attributes to the West Seattle Blog. This photos was taken on 17 December 2012, when the water level, as measured by the NOAA tide gauge in Seattle, reached 14.47 feet relative to MLLW:

This water level was just shy, by a whisker (0.01 feet to be exact) of the record water level measured in Seattle on 27 January 1983.

Next consider this photo, taken at the same exact spot by Melissa Poe of Washington Sea Grant on 29 November 2014:

On this day, still water level reached just 13.11 feet:

Well shy of the near record water level of 14.47 feet associated with the event from 17 December 2012...yet the flooding extent is essentially the same. The obvious difference? A local wind storm generating waves:

So what this tells me is that the data that we derive from tide gauges, and that we use to assess the coastal flooding hazard now and in the future only tells us part of the story, and we need better information on waves in order to take things to the next level. This is nothing new, Peter Ruggiero and others have been telling us for years that we need to account for "total water level"...including the influence of waves. But largely that message has focused on the substantially more energetic wave climate of the outer coast of the Pacific Northwest. Clearly we need to account for waves in the inland waters as well. Now, if only we had data...

Wednesday, April 29, 2015

Coast Nerd video

Last weekend was the 2nd Annual River and Ocean Festival, held in Forks, WA in association with the Washington Coast Clean-up.

Make sure you make room for the 2016 film festival in your schedule!

I help to organize this event because I think we are entering this great age of small-scale film-making, enabled by digital technologies. And that means that, more and more, we are seeing perspectives and views into other peoples lives and experiences that we've never had before. The River and Ocean Film Festival is designed to showcase films about the west end of the Olympic Peninsula, but I've also been tracking films about coastal science and hazards. A few that have come up lately:

Here is a nice little series I found just last night, by the St. Petersburg (Florida) Coastal and Marine Science Center of the USGS. I love this!:

While I am a giant fan of the USGS Coastal and Marine program, I think that from the standpoint of nerdy videos about coastal geology and geomorphology, that this video series from Ireland takes the grand prize. Here is an example:

I love this stuff!

A bit closer to home, is this piece by Oregon Sea Grant focused on the coastal effects of climate change, part of a series (find them all here):

and there are also some really nice coastal videos at the Science Earth youtube channel. Here is an example:

And then we get into the one-offs. As an example, here is an interesting film by The Verge focused on design strategies for protecting Manhattan after Hurricane Sandy:

Thursday, April 23, 2015

Rialto Beach

Its been a while...

Had the chance to survey Rialto Beach earlier this week, on the coast of Washington in Olympic National Park, as part of my shoreline morphology monitoring program (which is, by the way, looking for a better name...should you have any ideas). And I decided to post about it because...MAN, WHAT A BEACH! Rialto is so very cool...every time I go out there I am blown away by its morphology and the degree of variability it exhibits.

The first thing you notice at Rialto are logs. Does this beach ever have logs (see photos above)! And these aren't small logs either - these are massive old growth trunks grounded in the upper intertidal. These things are definitely influencing shoreline morphology and evolution...they must be...but exactly how isn't totally clear to me yet.

The next thing that always strikes me about Rialto is the evidence of erosion everywhere...mostly in the form of dead trees:

The odd thing, though, is that based on survey data from the last few years, it doesn't look like Rialto is eroding really at all over shorter, annual, timescales (though it is subject to seasonal variability). That suggests to me the likelihood that this shoreline is pretty subject to erosion related to relatively infrequent El Nino winters, or perhaps the once-or-twice-a-century extreme storms. I know that there have been big changes out there within recent living memory - I would love to hear any stories...

But the other thing I've started to really take note of at Rialto are exposures of what appears to be some base strata that the ocean is cutting into:

It would be interesting to date some of these exposures, and try to work out what they tell us about the evolution of the shoreline on the coast of Washington over longer time-scales.

Finally, I am always blown away by the ocean's power on display at Rialto:

Above, for example, is a photo of a sizeable small boulder wedged into the crook of a root wad, which is itself buried in the beach substrate. Now its entirely possible that this rock travelled with the root wad, but it sure looked like the thing had been forcibly jammed into place, and waves have been known to move bigger. The waves at Rialto always seem more powerful to me as compared to just across the river in La Push, which I've attributed to perhaps the off-shore bathymetry, or the beach orientation. Regardless, this was an indication to me of the forces at work on this beach.

Thursday, March 5, 2015

Second Beach

The view from Second Beach, Olympic National Park, this weekend

Had the opportunity to visit Second Beach over the weekend, and survey First Beach at La Push a few days ago with students from the Quileute Tribal School and Forks High School. Its been a beautiful stretch of weather, and the coast is the right place to be at times like these.

A bedrock exposure at the south end of Second Beach, completely coated with Aggregating Anenomes (Anthopleura elegantissima)

A few observations from Second Beach...

I was struck at Second Beach by the volume of the looked like the beach had accreted substantially since the last time I was there a few months back. Even at a mid-level tide the beach was broader than I remembered:

On the upper beach, many large logs were partially buried by sand:

Large logs at Second Beach partially buried by fresh deposition

Is this a localized episode of accretion at Second Beach? Or is there something about the weather recently (relatively mild, small waves, etc.) that has pushed sand up into the intertidal? I'm curious now to work up our data from First Beach, and see how the profiles look...