Dune Restoration Could Increase Resilience to Sea Level Rise

July 27, 2023, 9:16 am 6.0k Views 59 Comments

By Sonia Fernandez, UC Santa Barbara

Over the last several years, the residents of Santa Monica, a coastal city on the edge of Los Angeles, saw something neither they, their parents, or perhaps even their grandparents had ever seen before: a three-foot-tall dune system rising gently from the flat, groomed expanse of one of the world’s most famous urban beaches. It’s a six year alliance between sand, wind and vegetation, and, according to UC Santa Barbara researchers, it’s one way to enlist nature to help protect the coast from the impacts of climate change.

“The project was really to assess whether we could naturally grow dunes on a heavily urbanized, mechanically raked beach that had been that way for more than 70 years,” said Karina Johnston, a doctoral student at UCSB’s Marine Science Institute (MSI) and the Bren School for Environmental Science & Management, and lead author on a paper in Frontiers in Marine Science. “Could it work? Could it inform natural solutions to help protect our coastline from sea-level rise?” The short answer: quite possibly.

The threat of sea-level rise has become an issue for all coastal cities around the world as they grapple with warming oceans, more intense storms and flooding events. For heavily populated stretches of coast, such as Santa Monica Beach in Los Angeles, the issue is especially nuanced: City planners have to walk the line between protecting the coast and keeping it available to the millions of visitors it receives each year.

“At the start of the project, considerations were centered around balancing ecology, beach access and the needs of local residents and businesses,” said Shannon Parry, chief sustainability officer for the City of Santa Monica. “Given the popularity of Santa Monica Beach, the project needed to be interactive and accessible.”

Beach grooming (or raking) is a coastal management measure undertaken generations ago to pick up trash, remove seaweed and make the beach more appealing for visitors.

“Those management activities have been in place for decades on urban beaches, so it’s created an institutionalized construct of what a beach should look like,” Johnston said.

a flat beach landscape with the telltale lines left by rakingPhoto Credit: Karina Johnston

Though well-intentioned, the practice of heavily raking the top few inches of sand several times a week and picking up kelp wrack does keep the beach free of debris, but it also flattens the natural landscape of wind-swept dunes held together by natural vegetation, impacts biodiversity and reduces habitat for wildlife. These unnaturally wide stretches of sand have since become the iconic look of southern California beaches, with coastal cities spending millions of dollars each year to maintain it.

dune plant with dark pink flowers

Red sand verbena (Photo Credit: Karina Johnston)

But with the growing threats of climate change and sea level rise, people who study and manage California’s urban beaches are taking another look at beach grooming. In collaboration with the City of Santa Monica and The Bay Foundation and other partners, Johnston and MSI researchers Dave Hubbard and Jenifer Dugan in 2016 started a long-term experiment, sectioning off three sides of a 1.2 hectare (about 3 acre) stretch of Santa Monica Beach with sand fencing, and sowing native dune plant seeds (red sand verbena, beach bur, beach salt bush and beach evening primrose). Then they waited.

And waited.

And waited, conducting scientific surveys throughout the study period, and turning to UCLA postdoctoral researcher Kyle Emery to document the long-term results via drone surveys.

“The success of the project was evident on the ground, but the aerial view from the drone provided an entirely different perspective in which the restoration site stood out like an island within a groomed landscape,” Emery said. “The data we collected with the drone surveys allowed us to build digital elevation models and estimate the sand accumulation and increase in elevation of the restoration site relative to the adjacent beach.” Six years after it began, the general elevation across their pilot study area increased by about 0.3 meter (about 1 foot), including a higher foredune ridge with a 0.9 m maximum elevation and 1-m dunes along the perimeter.  The accumulation of sand into dune forms was assisted by native vegetation, which trapped sand as it blew into the area, forming hummocks and dunes.

Humans weren’t the only ones who noticed the new landforms; shorebirds, and especially the threatened western snowy plover, had started to make use of the new dune landscape to roost.

Waiting for nature and conducting scientific research was probably the easier job. The collaborators simultaneously undertook a massive information campaign aimed at the local beach community, explaining what the project was for and what they could expect.

a Western snowy plover

Western snowy plover (Photo Credit: Karina Johnston)

“The City of Santa Monica was a fantastic partner,” Johnston said. “They are very forward-thinking about climate change.” City staff dedicated time and effort to sending out mailers, building a website, generating blogs and leveraging social media. They also added informative signs at the site to explain the importance of coastal resilience and set up meetings so the researchers could directly answer any questions from the public.

What’s important to remember, according to the researchers, is that human involvement was also part of the vision. “What we really wanted to do was to let people interact with the site and to not impact recreational opportunities,” Johnston said. Hence, while the area was marked off with signs requesting minimal disturbance, the oceanward side of the plot was unfenced to open it to recreation.

Beachgoers walking through the project site
Beachgoers use the walkway through the project site to access the shore (Photo Credit: Karina Johnston)

The public response was “incredibly positive,” according to the researchers, due in large part to the access provided for recreation, and to a walkway through the experimental plot. It became so popular that that people would go out of their way to walk through the middle of the site on their way to the water’s edge and take pictures or birdwatch.

Not everyone was enthusiastic about the project from the start. One longtime resident was vocal in her opposition to the project at the beginning of one public comment gathering session.

“We started giving a presentation about why the project was happening, and our goals, and we started showing pictures of other places that had dunes and vegetation along the beaches, and she stands up in the middle of the presentation. I froze: What was she going to say?” Johnston recalled.

“And she turns to the City of Santa Monica and stares at them and says, ‘Why is this project not bigger?’ She became one of our staunchest supporters, and we recognized the important value of community input throughout the process.”

“The Santa Monica Beach Pilot Project is a successful proof of concept for scalable, affordable coastal adaptation solutions that address the risks from climate change and coastal sea level rise,” Parry noted. “Through dedicated public engagement and thoughtful ecological design, the project was able to strike a balance between allowing sensitive natural processes to take place and achieving accessibility for Santa Monica beachgoers and residents.”

For all this effort, however, are the new dunes going to do what everyone hopes they will do?

“The dune building is going faster than the current rate of sea level rise,” Hubbard said. “So that’s really good. You could even have a disturbance and it could rebuild itself and catch up again.”

The last round of winter storms provided some evidence of this resilience, something the researchers hope will buy time as Santa Monica adapts to coastal erosion and climate change. But time, and even bigger storms and wave action will tell whether Nature can rise to the challenge of protecting the urban coast.

“We’re trying to create an alternative vision of what southern California beaches can be and people can choose for themselves what kind of beach they can have.”

Not all groomed beaches will respond to nature-based interventions such as this. Santa Monica Beach is part of a local littoral cell that naturally receives sand cycled in by wave and wind. “This approach is going to be suitable in some areas,” Hubbard said. “It’s not appropriate for other areas that are narrower.”

However, the success of this venture so far is something the scientists hope will inspire other sandy beach researchers and managers to investigate as a possibility for nature-based coastal adaptation. Ideally, field experiments and monitoring should last as long as it takes to gauge factors such as how large dunes can get, whether or not vegetation can re-seed itself and if the dune can self-repair after a significant disturbance. This could take up to a decade.

three photos showing the change in the landscape of a section of beach
The evolution of the landscape at the start of the project in 2017 (left) in 2018 (middle) and in 2022 (right)

“One of the highlights of this study is that we actually tracked this project from the beginning and out to more than six years,” Dugan said. Most of the studies they encountered in preparation for this project had done only a few years of monitoring and thus provided incomplete knowledge on the effects of rewilding sections of beach. She suspects that some of these short-term projects could have reported higher levels of response had there been a longer period of monitoring.

“Now we have all this rich information,” she said. “We know which plants really built the dunes, and where the foredune was likely to form on this groomed beach. All these findings  can be applied to other coastal dune restoration projects.”

For now, the collaboration will continue to monitor the experimental site, especially as this ongoing El Niño weather cycle brings higher sea levels and bigger waves. More information means more options for adaptation.

“We’re not doing this project in a prescriptive way,” Hubbard said. “We’re trying to create an alternative vision of what southern California beaches can be and people can choose for themselves what kind of beach they can have.”

Research on the study was also conducted by Melodie Grubbs at the Morro Bay Estuary Program.

researchers on the beach with a drone
Photo Credit: Karina Johnston

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  1. Dune restoration sounds like a great idea, although there is probably a place for groomed beaches in many areas too. However, sea level has little to do with it. Despite dire claims and predictions, there is no measurable deviation from the long term sea level trend. Here is the NOAA tide gage data for Santa Monica going back to the early 1930s showing no recent change in the long term sea level trend. Tide gages in other locations show the same.
    https://tidesandcurrents.noaa.gov/sltrends/sltrends_station.shtml?id=9410840

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  2. Ok sac, can you provide me the data from any tide gages showing a deviation from long term sea level trends? NOAA has them all over with data going back to the 19th century in some locations such as New York City. If your theory that global sea level is rising at an accelerating rate is correct, then tide gages all over the world must show a recent deviation from long term trends. If you can’t show tide gage data from all over the world deviating from long term trends, then your sea level rise theory is proven false. That’s science. If there is no data that could prove your sea level rise theory false, then it’s not falsifiable and is therefore not science.

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  3. You have that correct. The tide gauge data set is the only thing relevant to what happens at the beaches with respect to seal level change.
    Satellite measurements are not applicable for determining sea level at the beaches due to interference with the land. That’s a known limitation with the satellite measurements. Therefore the tide gauges are the only data set that matters. The global warming fanatics will dismiss the importance tide gauge data without disclosing the satellite data cannot measure sea level changes at the shore due to the ocean-land interface interference.
    That’s why NOAA has to maintain both data sets. You can look at the tide gauge plots from all over the world, some going back more than a century. Failure to accept the importance of the tide gauge data is true science denial.

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  6. The noisy climate clowns are back, this time with their one-note melody about tidal gauges.
    To see what reality is telling us, no matter what we choose to believe, peruse any of these sources:
    https://www.vims.edu/newsandevents/topstories/2021/slrc_2020.php
    https://www.cisa.gov/topics/critical-infrastructure-security-and-resilience/extreme-weather-and-climate-change/sea-level-rise
    https://sealevel.nasa.gov/faq/8/is-the-rate-of-sea-level-rise-increasing/#:~:text=Yes.,(3.4%20millimeters)%20per%20year.
    https://sealevel.nasa.gov/understanding-sea-level/by-the-numbers
    https://sealevel.nasa.gov/understanding-sea-level/global-sea-level/overview
    https://www.epa.gov/climate-indicators/climate-change-indicators-sea-level
    https://www.jpl.nasa.gov/edu/teach/activity/graphing-sea-level-trends/
    https://climate.copernicus.eu/climate-indicators/sea-level

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  7. Scientific pursuit says that anytime someone says “the science is settled” it is not and should not be.
    Currently an overwhelming amount of research might show one thing, but that does not mean it doesn’t ever change:
    The discovery of the accelerating expansion of the universe, challenged the science that had held that the expansion of the universe is slowing down due to the force of gravity.
    Recent studies have found that the majority of the universe is made up of dark matter and dark energy, which challenges the science that claimed for decades that visible matter is the dominant form of matter in the universe.
    The human brain is able to create new neurons even in adult age, this challenges the science that held neurogenesis is limited to early childhood.
    What if everyone just accepted these things and had stopped testing, looking? Skeptics perform an invaluable service. Sycophants on the other hand are the people who get us nowhere

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    • 12:55 – great points. I just want to know how they think they benefit from ignoring the science? Do they think they’ll somehow be rewarded? Or is it more that, they don’t want to have to do anything different in their lives that would benefit someone other than “me, me, me?”

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    • Sac, his comments at @6:04 were not deficient. Do you really need “sources” for the claim that the universe is expanding at an accelerated rate and the is made up of mostly dark matter? He also did not claim ocean levels weren’t raising, the claim was there rise has been negligible, but yes, still a rise, and the corresponding tide data was provided. @12:55, were has anyone here said we should continue the status quo? Calling this climate alarmist propaganda for what it isn’t doesn’t mean we should treat the planet like shit and not work to reduce our impact on it.

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    • VOICE – “@1:34 AM – can you please share specifically where Edney’s knowledge of science is deficient?”
      I’ll help with that. It’s every single thing he says. Might help you, Edney, CHIP, et al if you actually provided scientific sources for your outlandish claims. You know, like everyone else is here. Where’s your sources? PROVE that the ocean level is not rising. Put up or…. well, you know.

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    • It’s especially ironic that these deniers are trying to shut down study of how we’re affecting the climate by saying we should just continue the status quo, there’s nothing to see or learn here, and what they want to believe is what must be true. And it’s all because of politically motivated garbage pushed into their social media bubbles by the big money carbon fuels industry.
      What fools. The middle east is already becoming uninhabitable by humans outdoors during some days in the summer, and that number is increasing. But, we should all just sit around until the death zone becomes the entire planet all the time, because those oil and coal subsidies need to be paid by somebody.

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  8. The idea that we should work on protecting habitat against a rising tide is not unlike that of King Cnut who allegedly thought his royal command would stop the tide from coming in. We cannot stop global warming overnight. But we can work to slow it and eventually reverse it by proper and ethical alterations to our energy production and life style. This is where we should put our efforts, not new berms or replacing dying plants.

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  9. Sacjon
    You can google the three scientific reversals listed for a start?
    That right there would show that the bulk of what I wrote is scientific fact.
    You are aware that Einstein’s Theory of Relativity is constantly being tested?
    https://www.scientificamerican.com/article/einsteins-greatest-theory-just-passed-its-most-rigorous-test-yet/#:~:text=Einstein's%20Greatest%20Theory%20Just%20Passed%20Its%20Most%20Rigorous%20Test%20Yet,-The%20MICROSCOPE%20mission&text=Scientists%20have%20demonstrated%20that%20Einstein's,for%20more%20than%20a%20century.
    How about this. I stipulate that there is warming, OK? You tell me using your depth of scientific knowledge exactly what percent of that warming and associated ocean rise is anthropogenic?
    You can’t. Even if you could, in a year or two it might change. That is OK because that research is ongoing.
    Compare skeptic vs. sycophant (you can look up sycophant on your own)
    Skepticism in science: Scientific skeptics maintain that empirical investigation of reality leads to the most reliable empirical knowledge, and suggest that the scientific method is best suited to verifying results. Scientific skeptics attempt to evaluate claims based on verifiability and falsifiability; they discourage accepting claims which rely on faith or anecdotal evidence. Carl Sagan emphasized the importance of being able to ask skeptical questions, recognizing fallacious or fraudulent arguments, and considering the validity of an argument rather than simply whether we like the conclusion.
    My personal skepticism towards AGW is of the ongoing unsubstantiated by results, claims about what is going to happen because of AGW like this one from March 2000 London Times citing Dr David Viner, a senior research scientist at the climatic research unit (CRU) of the University of East Anglia (Premier institution on AGW in UK):
    “However, the warming is so far manifesting itself more in winters which are less cold than in much hotter summers. According to Dr David Viner, a senior research scientist at the climatic research unit (CRU) of the University of East Anglia, within a few years winter snowfall will become “a very rare and exciting event”.
    “Children just aren’t going to know what snow is,” he said.
    From 2010 Here is a view of record snowfall in UK as seen from Space
    https://www.universetoday.com/49891/uks-big-snowfall-as-seen-from-space/
    Now from Washington Post 1/06/2021 and via ongoing scientific inquiry due to the science not being settled:
    “David Robinson, a New Jersey state climatologist and Rutgers University professor, says rising temperatures may actually cause snowstorms to dump more snow.
    Snowstorms are complicated. “To get snow, you need moisture and you need subfreezing temperatures,” Robinson says.
    Without moisture in the air, there can be no precipitation, rain or snow. Robinson says there is evidence of snowstorms becoming stronger because of the relationship between moisture and precipitation.
    “The warmer the air becomes, the more moisture it holds. So, if it’s warming and still cold enough to snow, you can get more snow,” Robinson says.
    Thank you to Dr. Obvious Robinson, we have someone who may not think 1.5C of warming is enough to keep the northern latitudes from having freezing air in the winter at the same time as there is moisture. Dr. David Viner may be right in some future particular year, but it remains highly unlikely that an entire generation in the UK will grow up never seeing snow due to influences of AGW.
    Final question: Sacjon. Are you OK with a climate accord that lets the worlds greatest polluters to increase their pollution every year, unchecked, no limits until the aimed date of 2030? Before answering note that China hedged there and said it was going to grow emissions unchecked from 2020 to 2030 “aiming” to possibly begin to throttle down emissions in 2030. Follow up question: What are we going to do, what is your plan for the world if we get to2030, 2035, 2040 and China, India, the rest of Asia, Africa are still increasing emissions? 2040 is only 17 years away

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  11. Actually, ummm due to coastal nuances, the west coast and in particular the SB Coast, sea levels will always stay somewhat lower, east coast of US sea levels somewhat higher, and Alaskan sea levels are predicted to continue to lower substantially. Your team posted the map with the data, I’m just reading it. Why would the coast of Alaska see a retreat in sea levels according to NOAA? Because AGW is melting glaciers and when glaciers retreat, the water levels along that coastline area drop. I’m not lying, its your teams data and science, and I’m not saying it disproves overall sea level rise. People haven’t read or assimilated the data they cling too like an old school religion. You guys just downvoted someone who repeated the data that was linked by your side of the argument. That is funny. Ignorant, but funny

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  12. From NOAA
    “Unlike Alaska, most of the West Coast was not covered by ice sheets [during the ice age]. So glacial adjustment isn’t affecting these stations. As a result, many of them are experiencing local sea level rise that is close to the global average. This pace means that sea levels along the U.S. West Coast have been rising more slowly than those along the U.S. East Coast. This East Coast-West Coast difference in rates of relative sea level rise is projected to continue in coming decades.”
    So no, it won’t eventually follow suit. Neither will Alaska. It will continue to follow the course we already see though. That is where the “(alexblue) Line” and Greenland problem butt up against science. Rudimentary geography lesson. Blue line Greenland with Atlantic Ocean vs. blue line in Santa Barbara with Pacific Ocean. Greenland Atlantic. Blue line on Greenland would recede but probably rise in Netherlands and Hudson Bay. I’ll let you look up why. Water from Greenland is not going to raise the sea levels in Santa Barbara. Glaciers in Alaska on Pacific predicted to cause different issues than Greenland glaciers in Atlantic. Who could have known? Anyone, but certainly not the people at UCSB in 2002 who saw Al Gore’s “Inconvenient Truth” and immediately conflated eastern seaboard and western seaboard rises. Eastern seaboard has 3X the rise of Western seaboard and the scientists seemed to think that should continue everywhere into the foreseeable future. Why not? Because Greenland is in the Atlantic Basin and, it is not Alaska. Greenland is covered with ice and snow. Alaska is covered in forest and tundra and is in the Pacific Basin.
    What about Antarctica you say? Well, even the most militant AGW proponents and deniers have to acknowledge that Antarctica average temperature has risen 1C since 1955 and that the interior average is still -71F and the coastal average is still 14F and most of that giant 1C increase has been driven by temperatures on the peninsula.

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