7 ms·

An experimental beach barrier could be key to rebuilding eroding coastlines

96 points by tintinnabula 4y ago

czcar 4y ago
This video of the beach and the restoration project was a lot more visually explanatory https://www.youtube.com/watch?v=5w18tEjEePg https://www.youtube.com/watch?v=5w18tEjEePg
- farrisbris 4y ago
  It really was. Thanks for posting it
mkoubaa 4y ago
I wish there was software that reads an article and spits out a tl;Dr. I don't have patience to read a narrative, give me the info In any case, this was worth the read. Its really counterintuitive that loose rocks don't just get swallowed into the ocean
- stolen_biscuit 4y ago
  > I wish there was software that reads an article and spits out a tl;Dr. I don't have patience to read a narrative, give me the info It's really not that long and if you're genuinely interested you make an effort to read it. Not everything can be boiled simply down to a handful of sentences without losing key detail.
- chiefalchemist 4y ago
  I believe you can paste into into ChatGPT and it'll do that for you. I have yet to try it but I'm thinking I've seen it mentioned in vids on YT.
  - varenc 4y ago
    Here's ChatGPT's summary with the query "Please summarize this article in 3-4 paragraphs: <pasted article>" ======== A group of residents in North Cove, Washington State, has developed a solution to the erosion of their coastline using piles of loose cobble. After dropping a load of rocks from the end of a road in 2016 to see what would happen, local farmer and drainage commissioner David Cottrell expanded the project to create a two-kilometer-long berm of rocks and stumps that shifts with the waves and collects sand, rebuilding the beach. The community's solution looks less like conventional structures such as sea walls and more like the dunes and berms that centuries of storms and tides build on their own, resembling the techniques many Indigenous communities use to cultivate shellfish. As climate change progresses, coastal communities worldwide are searching for solutions to combat rising sea levels. Hard barriers like sea walls and riprap often cause further erosion and are expensive to build. By contrast, building beaches back could be enough to prevent some of the catastrophic land loss that many states in the US are forecasting due to climate change, according to coastal resilience experts. North Cove's solution is influencing projects nearby and in California, Europe, and Guam, and is transforming the tools that agencies and communities can apply elsewhere. Engineers have long depended on rigid sea walls, and North Cove's berm is showing the benefits of a softer approach. The project has been successful in rebuilding the beach, and some species, including clam beds and shorebirds, have returned to the area.
    - meling 4y ago
      That’s pretty good actually. I couldn’t see any significant mistakes…
    - mkoubaa 4y ago
      That's perfect actually. I'd pay for a browser extension that does this
  - zx8080 4y ago
    How do you know chatgpt does not hallucinate?
ggm 4y ago
The key point here is that its not a permanent construct, its using natural mechanisms to slow down wave energy and encourage regrowth of the dunes and littoral zone. In Australia we've had a lot of permanent fix approaches which were massively counter-productive. If you want to stop sand being mobile then be prepared to lose it entirely. Really? about 200m-500m back from the waters edge is probably the limit of where routine construction should take place. it doesn't make for million dollar views but its safer for that property owner, the commons (assuming you live in an economy where the intertidal zone is public access) and the dunes. The Gold Coast is a huge sweep of beach which depends on sand from the river Tweed, which was walled off to make a clear run for boats, and now they have to pump sand to replenish. Noosa depends on sand pumping. Rocks might help, they might even make some fantastic surf breaks but they wind up altering the nature of the beach. If you want a beach like surfers paradise or main beach or noosa, you really don't want rocks. The berm he's made suits his local hydrology. It won't be exactly the same everywhere. I kind-of hate being the typical HN naysayer. I'm not a tidal engineer or an ecologist or civil engineer. This is stuff which is discussed quite a lot in Australia, since we cling to the coast and an image of ourselves as "in love with the sea" it becomes increasingly necessary to look at how to hold on to what we've got. The run of sand up the eastern seaboard of Australia is amazing. (its like barchan dunes, permanently on the move, in our case south-to-north) I've visited some of the beachfronts of Washington state and Oregon and they're glorious. Huge trees litter the tide line, amazing to see. We've nothing like that in Australia really, our rivers aren't full of giant redwood logs like that. We have different problems with disappearing Kelp forests, as does the Californian coastline, Oregon might have some of the problems Washington State does.
- floeng 4y ago
  You’re absolutely correct that in this area, his dynamic berm fits the hydrology, and that these are not good solutions in other places. Examples: - If the coast is too steep, the rocks won’t reach an equilibrium, and you now just have erosion of rock before your erosion of sand. - If egg-laying sea/coastal life needs sand like sea turtles or some birds - Surfers and tourism (as you mentioned) - If the sand erosion is acting as a source for something downstream; stopping the sand movement will cause erosion in that area (nourishing the beach with sand would probably be a better fit) (Edited formatting)
jeffbee 4y ago
These people must have bought these properties sight-unseen by mail or something. Why would you build a house were the beach retreats tens of meters per year?
- mrweasel 4y ago
  We have the same issue with a stretch of land in Denmark. There's part of the country where the North Sea erodes a tall sand cliff. The view is great, so people decided to build holiday home on top of it. People pay $200.000+ for these houses, then complains that nothing is done to secure the cliff when the sea inevitably eats another couple of meters the following winter. I can maybe see it being reasonable if you purchased the house 50 years ago, when the sea was really fare away. What I don't get is why you by a house 5 meters from a cliff, when you know that the sea can eat 2 meters in a winter. Why should tax money go to secure your poor investment? These houses are essentially worthless, yet priced like it's a 30 year investment. Hilariously some of the owners have been forced to pay property tax on lots that a half way down the cliff or out in the sea.
  - sidewndr46 4y ago
    You're looking at a microcosm of the phenomenon, but effectively you're just seeing the tragedy of democracy. Once a group realizes it is more cost-effective to just lobby the government to do something than doing it themselves, they'll just do that.
- gcanyon 4y ago
  It's possible the houses are old, and built before people realized what was happening. Others in this conversation have blamed the damming of the Columbia river, which occurred in the 1930s, so maybe the effect wasn't present before that.
floeng 4y ago
This… isn’t experimental. While the US Army Corps of Engineers might not have updated their shore protection manual to include “dynamic breakwaters [and beaches]”, we have design formulae to say what size rocks and what thickness of fill you need for your desired steady state* profile. Bonus points because the smaller rocks are significantly cheaper than the large, immobile armor units, and they can even withstand ice floes better if your coast freezes up. * there will still be seasonal variation based on summer/winter wave patterns and weather.
- bell-cot 4y ago
  That was my first reaction, too. Forget "US Army Corps of Engineers" - I'm thinking this technique was probably old stuff back when the Roman Empire was a shiny new thing.
mc32 4y ago
Instead of using concrete jax or tetrapods (as Japan does) they're basically using what would amount to concrete demolition debris (and natural rocks of different sizes) to shore up the coastline which is receding due to the damming of the Columbia River (which prevents sedimentary deposits) as evidenced from photos from the early 1900s --but despite that the author goes on to attribute it to sea level rise but never providing how much it rose by the 1900s or even today which would be informative, but I have suspect it's just the author's conjecture.
dendrite9 4y ago
I like seeing stuff from Hakai show up here regularly, I think they generally do a good job writing about interesting things around the water. The Demon river article about the catastrophic floods in BC last year is well worth the (long) read. I've shared it with a number of friends: https://hakai.org/the-demon-river/ https://hakai.org/the-demon-river/
analog31 4y ago
Artificial reefs and breakwaters would be a good use of oligarch yachts. Nobody's going to buy those things because they don't want to reveal who actually owns them.
tda 4y ago
A stable beachy coastline is in dynamic equilibrium. Erosion is the result of more sediment being washed away from the system than is deposited. The root cause of the disturbance in the system is probably some damn in a river which is mentioned in the article. A local measure that reduces wave energy creates a sediment trap, reducing or reversing local erosion.. However some where downstream from this site there is now less sediment coming in than is going out. So there it is going to erode now. These type of measures usually end up pushing the problem downstream (a coastal system has a dominant sediment transport flow direction). Actual solutions must look at an entire coastal system and usually involve continuous dredging, damn removal or lots of breakwaters, walls etc. This is all well known amd cam be modeled to a pretty good accuracy with software. However time amd time again a town solves their problem by pushing the erosion to their neighbours .
- wruza 4y ago
  A great video about river dynamics and equilibrium: https://youtube.com/watch?v=UBivwxBgdPQ https://youtube.com/watch?v=UBivwxBgdPQ
  - gcanyon 4y ago
    I watched that video yesterday! He's so good!
Animats 4y ago
The Ritz-Carlton Hotel near Half Moon Bay, CA is famous for their unauthorized dumping of large rocks on a public beach to prevent erosion taking out their cliff-top hotel. They were forced to remove the rocks.[1] Those pictures are a few years old. Compare Google Earth.[2] They're a few years from losing the golf cart path. The hotel might have another 20-30 years. [1] https://stolenhistory.net/threads/ritz-carlton-half-moon-bay-california.4358 https://stolenhistory.net/threads/ritz-carlton-half-moon-bay... [2] https://earth.google.com/web/@37.43372402,-122.4416652,22.97597245a,250.81525577d,35y,90.47729176h,78.20983856t,0r https://earth.google.com/web/@37.43372402,-122.4416652,22.97...
- gcanyon 4y ago
  I don't understand why they would be fined/forced to remove erosion abatement measures. Sure that might reduce beach access, but without it the beach will go away? I guess there will always be a beach, it will just move inland over time. I wonder how the California Coastal Commission will deal with the universal access requirement when the beach literally eats its way into private property.
  - Arrath 4y ago
    The key word there is "unauthorized". If they went through some official process with an erosion abatement/remediation plan and got the right review and approvals, they wouldn't then be forced to clear the rocks away.
  - Animats 4y ago
    It ceases to be private property when the sea eats it away. Everything below the high tide line is public property.[1] [1] https://www.slc.ca.gov/wp-content/uploads/2018/11/2017-PublicAccessGuide.pdf https://www.slc.ca.gov/wp-content/uploads/2018/11/2017-Publi...
    - gcanyon 4y ago
      Well that clarifies that. It's interesting that this sort-of automatic eminent domain doesn't require some form of compensation to the (previous) owner of the land. It also just sits poorly with me that the public's interest in a small portion of beachfront is resulting/going to result in the destruction of such a nice place -- albeit that I know almost none of the particulars.
jl6 4y ago
I’d probably want to protect my property too, but I can’t help but feel that the long-term solution here is some kind of plan for decommissioning coastal assets. Nothing is permanent, particularly where long-term shifts in weather patterns, sea levels, etc. may render residences and livelihoods unviable, and while this transformation of coastal geography is amplified by anthropogenic climate change, it’s not new and won’t ever go away. I am reminded of the two interpretations of the story of King Cnut and the tide[0]: the misconception that he tried to control the sea, and the actual story in which he was subordinate to it. [0] https://en.wikipedia.org/wiki/King_Canute_and_the_tide https://en.wikipedia.org/wiki/King_Canute_and_the_tide
- gcanyon 4y ago
  > decommissioning Sure, but they were losing 50 feet per year. It's reasonable to try to slow that down.
jsiepkes 4y ago
I think here in the Netherlands this is also done for a couple of years now [1]. Apparently they also used a "waste" product of steel manufacturing for it instead of just rocks. No idea if it was because of this experiment. [1] https://www.rijkswaterstaat.nl/water/waterbeheer/bescherming-tegen-het-water/maatregelen-om-overstromingen-te-voorkomen/vooroeververdediging https://www.rijkswaterstaat.nl/water/waterbeheer/bescherming...
qwerty_clicks 4y ago
Beach impermanence is a fact. Longshore current and erosion baffles are not new concepts. Encouraging people to just dump rubble on their beaches could have a lot of unforeseen consequences. This sort of citizens science mirrors anti-vax journalism.
gcanyon 4y ago
For anyone wondering what the neighborhood used to look like, here's a USGS map including streets from 1956: https://ngmdb.usgs.gov/img4/ht_icons/overlay/WA/WA_North%20Cove_242866_1956_24000_geo.jpg https://ngmdb.usgs.gov/img4/ht_icons/overlay/WA/WA_North%20C... And here's what's left today: https://goo.gl/maps/HXDdUSxcjXCpGeh26 https://goo.gl/maps/HXDdUSxcjXCpGeh26
samson8989 4y ago
In melbourne australia, we have been preserving our beaches with rocks forever, at least since the 1930's. We were losing 20m every 10 years, not 10m per year. I dont think this is a new concept.

96 points by tintinnabula 4y ago

This video of the beach and the restoration project was a lot more visually explanatory https://www.youtube.com/watch?v=5w18tEjEePg https://www.youtube.com/watch?v=5w18tEjEePg

farrisbris 4y ago
It really was. Thanks for posting it

mkoubaa 4y ago

I wish there was software that reads an article and spits out a tl;Dr. I don't have patience to read a narrative, give me the info In any case, this was worth the read. Its really counterintuitive that loose rocks don't just get swallowed into the ocean

stolen_biscuit 4y ago
> I wish there was software that reads an article and spits out a tl;Dr. I don't have patience to read a narrative, give me the info It's really not that long and if you're genuinely interested you make an effort to read it. Not everything can be boiled simply down to a handful of sentences without losing key detail.
chiefalchemist 4y ago
I believe you can paste into into ChatGPT and it'll do that for you. I have yet to try it but I'm thinking I've seen it mentioned in vids on YT.
- varenc 4y ago
  Here's ChatGPT's summary with the query "Please summarize this article in 3-4 paragraphs: <pasted article>" ======== A group of residents in North Cove, Washington State, has developed a solution to the erosion of their coastline using piles of loose cobble. After dropping a load of rocks from the end of a road in 2016 to see what would happen, local farmer and drainage commissioner David Cottrell expanded the project to create a two-kilometer-long berm of rocks and stumps that shifts with the waves and collects sand, rebuilding the beach. The community's solution looks less like conventional structures such as sea walls and more like the dunes and berms that centuries of storms and tides build on their own, resembling the techniques many Indigenous communities use to cultivate shellfish. As climate change progresses, coastal communities worldwide are searching for solutions to combat rising sea levels. Hard barriers like sea walls and riprap often cause further erosion and are expensive to build. By contrast, building beaches back could be enough to prevent some of the catastrophic land loss that many states in the US are forecasting due to climate change, according to coastal resilience experts. North Cove's solution is influencing projects nearby and in California, Europe, and Guam, and is transforming the tools that agencies and communities can apply elsewhere. Engineers have long depended on rigid sea walls, and North Cove's berm is showing the benefits of a softer approach. The project has been successful in rebuilding the beach, and some species, including clam beds and shorebirds, have returned to the area.
  - meling 4y ago
    That’s pretty good actually. I couldn’t see any significant mistakes…
  - mkoubaa 4y ago
    That's perfect actually. I'd pay for a browser extension that does this
- zx8080 4y ago
  How do you know chatgpt does not hallucinate?

ggm 4y ago

The key point here is that its not a permanent construct, its using natural mechanisms to slow down wave energy and encourage regrowth of the dunes and littoral zone. In Australia we've had a lot of permanent fix approaches which were massively counter-productive. If you want to stop sand being mobile then be prepared to lose it entirely. Really? about 200m-500m back from the waters edge is probably the limit of where routine construction should take place. it doesn't make for million dollar views but its safer for that property owner, the commons (assuming you live in an economy where the intertidal zone is public access) and the dunes. The Gold Coast is a huge sweep of beach which depends on sand from the river Tweed, which was walled off to make a clear run for boats, and now they have to pump sand to replenish. Noosa depends on sand pumping. Rocks might help, they might even make some fantastic surf breaks but they wind up altering the nature of the beach. If you want a beach like surfers paradise or main beach or noosa, you really don't want rocks. The berm he's made suits his local hydrology. It won't be exactly the same everywhere. I kind-of hate being the typical HN naysayer. I'm not a tidal engineer or an ecologist or civil engineer. This is stuff which is discussed quite a lot in Australia, since we cling to the coast and an image of ourselves as "in love with the sea" it becomes increasingly necessary to look at how to hold on to what we've got. The run of sand up the eastern seaboard of Australia is amazing. (its like barchan dunes, permanently on the move, in our case south-to-north) I've visited some of the beachfronts of Washington state and Oregon and they're glorious. Huge trees litter the tide line, amazing to see. We've nothing like that in Australia really, our rivers aren't full of giant redwood logs like that. We have different problems with disappearing Kelp forests, as does the Californian coastline, Oregon might have some of the problems Washington State does.

floeng 4y ago
You’re absolutely correct that in this area, his dynamic berm fits the hydrology, and that these are not good solutions in other places. Examples: - If the coast is too steep, the rocks won’t reach an equilibrium, and you now just have erosion of rock before your erosion of sand. - If egg-laying sea/coastal life needs sand like sea turtles or some birds - Surfers and tourism (as you mentioned) - If the sand erosion is acting as a source for something downstream; stopping the sand movement will cause erosion in that area (nourishing the beach with sand would probably be a better fit) (Edited formatting)

jeffbee 4y ago

These people must have bought these properties sight-unseen by mail or something. Why would you build a house were the beach retreats tens of meters per year?

mrweasel 4y ago
We have the same issue with a stretch of land in Denmark. There's part of the country where the North Sea erodes a tall sand cliff. The view is great, so people decided to build holiday home on top of it. People pay $200.000+ for these houses, then complains that nothing is done to secure the cliff when the sea inevitably eats another couple of meters the following winter. I can maybe see it being reasonable if you purchased the house 50 years ago, when the sea was really fare away. What I don't get is why you by a house 5 meters from a cliff, when you know that the sea can eat 2 meters in a winter. Why should tax money go to secure your poor investment? These houses are essentially worthless, yet priced like it's a 30 year investment. Hilariously some of the owners have been forced to pay property tax on lots that a half way down the cliff or out in the sea.
- sidewndr46 4y ago
  You're looking at a microcosm of the phenomenon, but effectively you're just seeing the tragedy of democracy. Once a group realizes it is more cost-effective to just lobby the government to do something than doing it themselves, they'll just do that.
gcanyon 4y ago
It's possible the houses are old, and built before people realized what was happening. Others in this conversation have blamed the damming of the Columbia river, which occurred in the 1930s, so maybe the effect wasn't present before that.

floeng 4y ago

This… isn’t experimental. While the US Army Corps of Engineers might not have updated their shore protection manual to include “dynamic breakwaters [and beaches]”, we have design formulae to say what size rocks and what thickness of fill you need for your desired steady state* profile. Bonus points because the smaller rocks are significantly cheaper than the large, immobile armor units, and they can even withstand ice floes better if your coast freezes up. * there will still be seasonal variation based on summer/winter wave patterns and weather.

bell-cot 4y ago
That was my first reaction, too. Forget "US Army Corps of Engineers" - I'm thinking this technique was probably old stuff back when the Roman Empire was a shiny new thing.

mc32 4y ago

Instead of using concrete jax or tetrapods (as Japan does) they're basically using what would amount to concrete demolition debris (and natural rocks of different sizes) to shore up the coastline which is receding due to the damming of the Columbia River (which prevents sedimentary deposits) as evidenced from photos from the early 1900s --but despite that the author goes on to attribute it to sea level rise but never providing how much it rose by the 1900s or even today which would be informative, but I have suspect it's just the author's conjecture.

dendrite9 4y ago

I like seeing stuff from Hakai show up here regularly, I think they generally do a good job writing about interesting things around the water. The Demon river article about the catastrophic floods in BC last year is well worth the (long) read. I've shared it with a number of friends: https://hakai.org/the-demon-river/ https://hakai.org/the-demon-river/

analog31 4y ago

Artificial reefs and breakwaters would be a good use of oligarch yachts. Nobody's going to buy those things because they don't want to reveal who actually owns them.

tda 4y ago

A stable beachy coastline is in dynamic equilibrium. Erosion is the result of more sediment being washed away from the system than is deposited. The root cause of the disturbance in the system is probably some damn in a river which is mentioned in the article. A local measure that reduces wave energy creates a sediment trap, reducing or reversing local erosion.. However some where downstream from this site there is now less sediment coming in than is going out. So there it is going to erode now. These type of measures usually end up pushing the problem downstream (a coastal system has a dominant sediment transport flow direction). Actual solutions must look at an entire coastal system and usually involve continuous dredging, damn removal or lots of breakwaters, walls etc. This is all well known amd cam be modeled to a pretty good accuracy with software. However time amd time again a town solves their problem by pushing the erosion to their neighbours .

wruza 4y ago
A great video about river dynamics and equilibrium: https://youtube.com/watch?v=UBivwxBgdPQ https://youtube.com/watch?v=UBivwxBgdPQ
- gcanyon 4y ago
  I watched that video yesterday! He's so good!

Animats 4y ago

The Ritz-Carlton Hotel near Half Moon Bay, CA is famous for their unauthorized dumping of large rocks on a public beach to prevent erosion taking out their cliff-top hotel. They were forced to remove the rocks.[1] Those pictures are a few years old. Compare Google Earth.[2] They're a few years from losing the golf cart path. The hotel might have another 20-30 years. [1] https://stolenhistory.net/threads/ritz-carlton-half-moon-bay-california.4358 https://stolenhistory.net/threads/ritz-carlton-half-moon-bay... [2] https://earth.google.com/web/@37.43372402,-122.4416652,22.97597245a,250.81525577d,35y,90.47729176h,78.20983856t,0r https://earth.google.com/web/@37.43372402,-122.4416652,22.97...

gcanyon 4y ago
I don't understand why they would be fined/forced to remove erosion abatement measures. Sure that might reduce beach access, but without it the beach will go away? I guess there will always be a beach, it will just move inland over time. I wonder how the California Coastal Commission will deal with the universal access requirement when the beach literally eats its way into private property.
- Arrath 4y ago
  The key word there is "unauthorized". If they went through some official process with an erosion abatement/remediation plan and got the right review and approvals, they wouldn't then be forced to clear the rocks away.
- Animats 4y ago
  It ceases to be private property when the sea eats it away. Everything below the high tide line is public property.[1] [1] https://www.slc.ca.gov/wp-content/uploads/2018/11/2017-PublicAccessGuide.pdf https://www.slc.ca.gov/wp-content/uploads/2018/11/2017-Publi...
  - gcanyon 4y ago
    Well that clarifies that. It's interesting that this sort-of automatic eminent domain doesn't require some form of compensation to the (previous) owner of the land. It also just sits poorly with me that the public's interest in a small portion of beachfront is resulting/going to result in the destruction of such a nice place -- albeit that I know almost none of the particulars.

jl6 4y ago

I’d probably want to protect my property too, but I can’t help but feel that the long-term solution here is some kind of plan for decommissioning coastal assets. Nothing is permanent, particularly where long-term shifts in weather patterns, sea levels, etc. may render residences and livelihoods unviable, and while this transformation of coastal geography is amplified by anthropogenic climate change, it’s not new and won’t ever go away. I am reminded of the two interpretations of the story of King Cnut and the tide[0]: the misconception that he tried to control the sea, and the actual story in which he was subordinate to it. [0] https://en.wikipedia.org/wiki/King_Canute_and_the_tide https://en.wikipedia.org/wiki/King_Canute_and_the_tide

gcanyon 4y ago
> decommissioning Sure, but they were losing 50 feet per year. It's reasonable to try to slow that down.

jsiepkes 4y ago

I think here in the Netherlands this is also done for a couple of years now [1]. Apparently they also used a "waste" product of steel manufacturing for it instead of just rocks. No idea if it was because of this experiment. [1] https://www.rijkswaterstaat.nl/water/waterbeheer/bescherming-tegen-het-water/maatregelen-om-overstromingen-te-voorkomen/vooroeververdediging https://www.rijkswaterstaat.nl/water/waterbeheer/bescherming...

qwerty_clicks 4y ago

Beach impermanence is a fact. Longshore current and erosion baffles are not new concepts. Encouraging people to just dump rubble on their beaches could have a lot of unforeseen consequences. This sort of citizens science mirrors anti-vax journalism.

gcanyon 4y ago

For anyone wondering what the neighborhood used to look like, here's a USGS map including streets from 1956: https://ngmdb.usgs.gov/img4/ht_icons/overlay/WA/WA_North%20Cove_242866_1956_24000_geo.jpg https://ngmdb.usgs.gov/img4/ht_icons/overlay/WA/WA_North%20C... And here's what's left today: https://goo.gl/maps/HXDdUSxcjXCpGeh26 https://goo.gl/maps/HXDdUSxcjXCpGeh26

samson8989 4y ago

In melbourne australia, we have been preserving our beaches with rocks forever, at least since the 1930's. We were losing 20m every 10 years, not 10m per year. I dont think this is a new concept.