Thursday, October 24, 2013

Ala Spit

My visit to Whiffen Spit two weeks ago had me thinking a lot about Ala Spit, and since I was in the area for meetings and other site visits, I figured it was worth checking out Ala while the tide was still pretty high and I still had a little daylight left. The tide was a little above MHHW and flowing rapidly into the lagoon across the neck of the spit.

Gravel Beach:  Ala Spit  (December 2011 -- from there you can link back to earlier posts)

This site remains one of the more interesting beach restoration stories of the last few years and I suspect is trying to teach us lessons that, if we pay attention, will help us all on future projects.

One of the lessons - the more obvious one - is that beaches can suffer from a number of ills and that successful restoration must address, or at least carefully consider, all of them. Sometimes the challenge is figuring out which problems are most serious and which are secondary.

I think the more complex lesson is about restoring dynamic systems - especially after several decades have gone past.  Removing a stressor does not necessarily take you back to where you would have been had the stressor never been applied. I'm trying to figure out how to use the word "hysteresis" here - because I think it is important. But I need to work longer on this argument than I have time for now -- and there will undoubtedly be other chances!

Google Maps:  AERIAL VIEW

Lone Tree Point

It's not hard to figure out how this place got its name, although I'm sure the Swinomish have more interesting words for it. Lone Tree Point is trying hard to be a tombolo - but lacks enough sediment to do it very well. What sand and gravel there is has built a broad, low bar out to the rocky islet, and then spread out northward as a spit that forms a lagoon across the mouth of the small creek that winds down through the Thousand Trails campground.

Google Maps:  AERIAL VIEW

The geology is messy here and the bedrock forms irregular shoals and reefs offshore. The strange tilted beaches I noted on Hope Island last year are a short distance away across a narrow channel (Hope Island:  May 2012).

Lone Tree provides an interesting contrast to other small barrier beaches in the area, such as the tombolos at Kiket Island (Kukutali Preserve) and the beach at Ala Spit (also the subject of the next post). The differences are partly due to the arrangement of the bedrock geology and partly due to the availability of beach sediment, among other things.

March Point

March's Point, or March Point? Either way, it's the peninsula that forms the eastern shoreline of Fidalgo Bay and is home to oil refineries and the piers necessary to unload all that Alaskan crude.

Google Maps:  AERIAL VIEW

It's also the site of one of the more interesting beach nourishment projects on the Sound in the last few years -- interesting in part because of its simplicity. The road follows the edge and erosion had cut away the bank, not only threatening the road, but eliminating the upper beach. This project (which I don't know too much about and will not say too much more about) involved placing gravelly sand along a stretch of beach and largely letting it figure itself out. Which it seems to have done very nicely and very quickly.

Sometime I'll come back and post about this project again - when I have more information and when the weather is more conducive to good photos.  I actually have better photos from previous visits, but I try to build the blog around the photos taken at the time (which in this case was last Thursday).


There's a new beach taking shape in Anacortes at the old Custom Plywood site.  The lumber mill closed down a long time ago and later burnt to the ground (or the water, since much of it was over water). They're currently cleaning up the toxic residue and redeveloping the site for a mixture of commercial and public uses.

Here are some earlier pictures - from back in the early days of the blog.
Anacortes:  April 2006

Google Maps: AERIAL VIEW

There's a lot going on here. The jetty at the north end is being extended, apparently to help shelter whatever ship yard or boat basin is planned for the north portion of the site. The southern portion of the site is dedicated to public use. A wetland, a small pocket estuary, will help buffer stormwater and restore some of the low energy habitat that may have once existed along portions of this shoreline.

The wetland/lagoon is sheltered by an artificial spit/berm with a coarse cobble core - I guess to keep it from washing away, not that that's very likely. The new beach, complete with drift logs, is being built on the outer face of this berm, and the estuary drains through a new tidal channel. The new beach is in turn protected by another spit, a pseudo-spit of coarser material that curves out into the bay - sort of a naturalistic breakwater.

This will be a fascinating landscape to watch evolve over the coming years. The vegetation in the wetland will have to sort itself out - adjusting to the tidal regime and the salinity of the new marsh. The beach will adjust to the waves and to the dynamics of the little tidal inlet, but I suspect will do fine. I am looking forward to launching a kayak there next summer some time. The outer spit is an interesting concept, but I'm curious to see what kind of shorelines actually become established on both its inside and outside edges.

Tuesday, October 15, 2013

Ogden Point

This is the last post from my three-day weekend in British Columbia. I promise! And this one isn't even a beach, but it is a coastal entry and one that I thought made a nice coda to my Vancouver Island beach tour.

I took the Blackball Line's Coho ferry from Victoria to Port Angeles - which means I got to sail out of Victoria's wonderful inner harbor, past Ogden Point, before heading across the Strait of Juan de Fuca to the U.S.

Google Maps: AERIAL VIEW

Ogden Point marks the entrance to Victoria Harbor. The summer cruise ships were all gone, but there were still crowds walking the breakwater, enjoying the great Sunday afternoon sun.

Ross Bay

I guess our little tour of southern Vancouver Island is taking on a bit more urban flavor - from Pacheedaht to Ross Bay. They're both spectacular beaches. But that's pretty much where the similarity stops!

Ross Bay is a large embayment on the south shore of Victoria. Dallas Road follows the back of the beach, protected by a large seawall. The seawall was built to protect the bluffs around 1912, following a particularly large storm that threatened to wash away the cemetery behind the southern portion of the beach.

Google Maps:  AERIAL VIEW

Around 2000, Victoria undertook a major gravel nourishment project, building a beach to protect the base of the seawall. The design involved several rock groins and an awful lot of well-sorted gravel (2-3 cms). The result is a remarkably steep beach (well-sorted, highly permeable gravel typically does this). This is probably a pretty durable solution to erosion and seawall damage.  And it's probably a more pleasant and more accessible beach with the seawall largely buried in gravel.

It is probably not a terribly great biological solution, at least when looked at through a narrow lens. The coarse gravel probably doesn't support a terribly rich biota, and certainty not the same biota that would occupy a sandier, less steep beach.  And the placement of the gravel would have covered whatever was there before. This is actually a pretty common debate about the use of nourishment - although the details vary from the Salish Sea to the Atlantic Seaboard.

Ultimately, I suppose you need to consider the alternatives. Maintaining the seawall presents its own problems - costs, safety, aesthetics - and is probably not doing the biology much good, either. Removing the seawall and trying to restore the beach of 100 years ago is probably not practical, for all sorts of reasons. Not only would the road and cemetery and any other development be lost, but the community would have to accept ongoing erosion and bluff retreat into the future. Nourishing the beach with a more natural mix of sediment would have benefits, but would also occupy a much larger footprint and represent a larger disturbance to the existing benthos, although in the long run, I wonder if it would be a more realistic option. Unfortunately, from an engineering perspective, sand is probably harder to keep where you want it and there might be a greater need to occasionally add more material.

These projects always have a lot more angles than I can represent in a simple blog post and in a setting like this, I can imagine there are some pretty strong opinions, too.  I guess if there was an easy solution, it just wouldn't be as interesting!

Monday, October 14, 2013

Gonzalez Beach

I like the geography of Victoria. A wonderful outer shoreline with rocky points, pocket beaches, and spectacular views of snow-capped mountains (Mount Baker and the Olympics). And a convoluted inner shoreline of deep harbors, narrow rocky waterways, and small estuaries (probably not as many as there once were).

Google Maps:  AERIAL VIEW

Gonzalez Bay is tucked into a rocky cove on the south edge of Victoria. Its sandy beach is publicly accessible through a small park at one end - and backed by seawalls and private homes that climb up the adjacent hills.

The beach itself is flat and sandy - quite the contrast to the steep, artificial gravel beach farther west at Ross Bay.

Whiffen Spit

Barrier beaches, in their simplest conception, are sort of a dynamic balance between loose sediment and wave action. One consequence of this is that they typically have smooth curves with few inflections. When there are sharp bends and discontinuities, it usually suggests that something else is going on. This may be some localized bedrock control or an underlying boulder lag, it may be related to a historic breach or an uneven supply of sediment, or it may be due to a human intervention such as an old revetment, the foundation of an old mill, or a groin.

Whiffen Spit stretches, somewhat crookedly, across the mouth of Sooke Harbor. It must be more than a kilometer in length, with a navigation marker at the tip. It's a wonderful park and on a pleasant October Sunday morning, half the dogs on Vancouver Island were out for walks on it.  I suspect that the footpath began as a road, perhaps access to whatever was built on the old concrete foundations farther out on the spit.

Google Maps: AERIAL VIEW

The neck of the spit is heavily armored with riprap and there is also a large groin, which together segment the base of the spit into small pocket beaches.  I don't know the story at Whiffen Spit, but typically the necks of these features are the narrowest parts and are often most susceptible to erosion. This portion of a spit is often actively migrating landward, aided by large storms that cause overwash, while the end of the spit remains more stable and may actually accrete.

When a road is built on this narrow part of the spit, it is inevitably damaged by big storms and the response is to armor and elevate the road. Over time, the base of the landform becomes less a spit and increasingly a causeway. This seems like it may have happened here. The groin would have been a logical, but short-sighted, fix to ongoing erosion, reducing updrift erosion, but aggravating erosion farther down the spit.

These things alone would help explain the irregular shape of Whiffen Spit, but as much as the human imprint on is obvious, I couldn't help but wonder if the shape of this spit also reflects some more fundamental geologic factors - an irregular glacial deposit, some underlying bedrock.  Even a small ledge of bedrock in the location now marked by the large groin might have led to a spit with this general configuration.  Another possibility is limited sediment supply, which can cause a barrier to begin to break down, scavenging itself to form shorter, more swash-aligned beaches - certainly a possibility for a spit like this without an obvious source of new sediment. An historic map of the spit would be a great resource right about now!

Whiffen Spit is a fascinating feature and one I'd love to know more about.  Much of the above is speculation, but it's a good opportunity to discuss some common aspects of spits, some of which may apply better here than others.  The scale and the history are different, but this place reminded me a lot of Ala Spit on Whidbey Island. There are definitely some similarities:

Gravel Beach: posts on Ala Spit (not necessarily in order)

When I put nine photos in a post, you know it's a pretty neat place. One of the more famous small inns in the Pacific Northwest is located right above the base of the spit -- seems like a good excuse to come back for a weekend to explore.

Sunday, October 13, 2013

Botanical Beach

I almost didn't include this post, but felt I couldn't leave it out.  Botanical Beach is an iconic site of rocky beach ecology, even though it's actually the shore platform, not the beach, that really gets the biologists excited. And the tide was far too high on this visit to get much sense for what it looks like during a summertime low tide, when the sea has retreated and left sandstone ledges pot-marked with tidepools.

I still thought the biology was impressive. Thick rain forest, small pockets of sandy backshore and dune grass, rafts of kelp tossed on the shore, and fresh bear scat near the high tide line (no signs of the culprit).

Google Maps:  AERIAL VIEW

There are actually several small pocket beaches along this exposed stretch of shoreline. The geology is cool, with sediments juxtaposed with much older metamorphic rocks, sometimes in spectacular ways - like these beautiful chunks floating in the sandstone. There are similarities to the exposures at Sombrio Beach and I'm guessing that the coastline sort of follows the contact between the Leech River rocks and the Tertiary sediments. I will proffer my normal lament - I wish I'd had a real geologist along!

Pacheedaht Beach

I've seen this referred to as Port Renfrew Beach and as San Juan Beach, but I've chosen to use the First Nations name that seems most appropriate for this beach and the name that goes with the campground that is strung out along its shoreline.  It's located at the head of Port San Juan, right across from the small town of Port Renfrew.

This is a large swash-aligned beach oriented to meet the waves coming into Port San Juan from the ocean. Each end of the beach is formed by a river mouth - the San Juan River at the southern end and the Gordon River at the north and there is a large estuary complex up valley from the beach.

Google Maps:  AERIAL VIEW

The beach itself is broad, with huge, steep gravel cusps, and the backshore is littered with an enormous amount of large wood. This must be an amazing place to watch during a big storm! The backshore grades landward into a distinct band of alder, before disappearing into the dark green forest behind it.