Surf’s Up!

Scientists help coastal communities plan for an uncertain future
Depoe Bay: Waves from a powerful storm crash into the seawall at Depoe Bay, Oregon. (Photo: Erica Harris, Oregon State University)

Waves from a powerful storm crash into the seawall at Depoe Bay, Oregon. (Photo: Erica Harris, Oregon State University)

If you love big surf, go to Depoe Bay on the Oregon coast during a winter storm. As swells rise and break offshore, winds whip ocean spray high into the air, but the waves move inexorably toward the harbor (the “world’s smallest navigable harbor,” reads a road sign), channel through rocks and, with a resounding shudder, launch a geyser over Hwy. 101. Enthralled tourists standing along the seawall sometimes yelp as they get a cold shower.

It all makes for good fun, but the pounding water carries a warning. Data from offshore buoys indicate that the largest waves are getting bigger. Coupled with slowly rising sea levels and the occasional El Niño, when warm waters pile up along our shores (as much as 19 inches higher than normal, due to thermal expansion), storms are eroding West Coast beaches and undermining bluffs at an increasing rate.

Examples of damage aren’t hard to find. In 2010, a series of El Niño storms “eroded the beaches to often unprecedented levels at sites throughout California and vulnerable sites in the Pacific Northwest,” said coastal geologist Patrick Barnard in a U.S. Geological Survey news release. Damage to a highway lane south of San Francisco cost $5 million to repair.

In 2006, residents of Gleneden Beach found their homes tottering on the edge of a cliff when a weekend storm removed nearly 20 feet of shoreline. In nearby Oceanside, during the El Niño of 1997-98, a 32-home development at The Capes was threatened by collapse of the bluff on which it stood. In southern Oregon during that winter, a storm breached dunes and destroyed Port Orford’s sewage treatment plant drain field. California coastal communities reported more than $100 million in property damage.

In the journal Geophysical Research Letters, Barnard and other West Coast researchers, including Peter Ruggiero of Oregon State University and Jonathan Allan of the Oregon Department of Geology and Mineral Industries (DOGAMI), raised the likelihood of increasing erosion risk in a changing climate and added: “If these trends continue, the combination of large waves and higher water levels, particularly when enhanced by El Niños, can be expected to be more frequent in the future, resulting in greater risk of coastal erosion, flooding, and cliff failures.”

While beaches wax and wane seasonally in a complex dance between land and sea, recent erosion losses have left some Oregon communities more vulnerable to the next storm. DOGAMI’s beach monitoring program has shown that in Tillamook County, beaches have not recovered from the 1997-98 El Niño. They have eroded landward an average of 30 to 60 feet and, in some areas, up to 150 feet. Rockaway Beach alone has lost an estimated 2.5 million cubic yards of sand. At Neskowin, beach retreat has enabled storm waves to threaten homes, flood streets and undermine rock-reinforcement — a.k.a. “rip rap” — in front of the dunes.

Wrestling with Risk

“Neskowin is at the head of the pin in terms of coastal erosion in Tillamook County. The community wishes to be proactive in addressing this problem,” says Mark Labhart, chair of the Neskowin Coastal Hazards Committee and a Tillamook County commissioner. “OSU research papers and direct access to professors have been invaluable in providing factual data on what has been happening in the past and what we might expect in the future so the community, the county and the state can plan for the next steps.”

Waves crawl up against the lower level of a structure in Neskowin, Oregon, during a storm in January, 2008. (Photo: Armand Thibault, Neskowin)

Waves crawl up against the lower level of a structure in Neskowin, Oregon, during a storm in January, 2008. (Photo: Armand Thibault, Neskowin)

At stake, he adds, are property values, roads, state park facilities and the relaxed quality of life for which the Oregon coast has become famous. Neskowin’s quiet, family-oriented character has lured vacationers for more than a century. According to local historical documents, Sarah Page and her husband settled on what was known as Slab Creek in the 1880s. She opened the first post office and called it Neskowin after she heard a Nestucca Indian refer to the creek by that name, meaning it had plenty of fish.

Today, the community has 408 homes (less than a quarter of which are occupied year around), a golf course and a condominium development, the Proposal Rock Inn. Nestled against Cascade Head to the south, Neskowin mirrors much of coastal Tillamook County, which has the highest percentage of second homes of all the state’s shoreline counties, according to the Oregon Coastal Zone Management Association (OCZMA).

Dedicated to protecting this idyllic enclave is a local group appointed by the county commission in 2009. The Neskowin Coastal Hazards Committee is composed of property owners and local and state officials and facilitated by Pat Corcoran, a coastal hazards specialist with Oregon Sea Grant. It has met with Ruggiero, Allan and other scientists. It has reviewed options (known as “Hazard Alleviation Techniques” or HATs) for reducing erosion hazards. With Corcoran’s help, it identified emerging research and delved into erosion processes and trends.

Working with Mitch Rohse, a planning consultant from Salem, the committee published a proposed legal policy in 2011 for counties to deal with the mounting risks: Adapting to Coastal Erosion Hazards in Tillamook County: A Framework Plan. Local planners and the county planning commission must review the document before it goes to the county commission for approval. Concurrently, the committee has raised more than $27,000 from private contributors, the Neskowin Homeowners Assn. and the Oregon Dept. of Land Conservation and Development for an engineering analysis of options and costs to protect the shoreline.

Elk Antlers over the Bed

Pat Corcoran talks with communities up and down the coast about getting ready for an event that could trump storm-driven erosion: the next tsunami. See Oregon Sea Grant’s new magazine Confluence.
Read more…

A first for Oregon, the draft framework plan calls on the county to adopt policies that help communities reduce their vulnerability to storm damage and erosion. Reflecting current state and local regulations, it draws from a variety of scientific sources, including former OSU master’s student Heather Baron’s 2011 thesis, in which she focused on “coastal hazard zones.” For her degree in Marine Resource Management, she evaluated the probability of erosion in each zone for 18 different climate change scenarios. Each scenario reflects a combination of risk factors: sea level rise, extreme wave heights and El Niño frequency and intensity. Her work builds on research by Ruggiero, Allan and their colleagues, who have used beach, wave and landscape data to define such zones along the Oregon coast.

If the plan were approved, properties in each zone would be subject to standards that reflect their vulnerability to the risk of future storm damage. Neskowin committee members expect that idea to generate debate over issues from development rights to property values. “Any time you put colored lines on a map that potentially affect property values, you get people’s attention in a hurry,” says Labhart.

Coastal Change

The threat faced by Neskowin and other communities doesn’t arise over night. It grows gradually from a series of seemingly harmless events, chief among them the construction of homes and condos and the seawalls that protect them. “A recent storm may have washed away a beach or destroyed homes lining the shore,” wrote retired OSU coastal oceanographer Paul Komar in The Sciences in 2000, “but merely blaming the weather is simplistic. Almost always, subtle factors have been acting over time to weaken the coast and make it more susceptible; the storm, when it comes, simply delivers the coup de grâce.”

Waves pound a beach and structure between Depot Bay and Boiler Bay on the Oregon Coast. (Photo: Erica Harris, Oregon State University)

Waves pound a beach and structure between Depot Bay and Boiler Bay on the Oregon coast. (Photo: Erica Harris, Oregon State University)

Neskowin’s case is puzzling, says Komar. When he started investigating erosion problems in the 1970s, Neskowin homeowners had problems with too much sand building up the dunes, blocking ocean views and even threatening to bury homes. “The change to erosion began with the 1982-83 El Niño and accelerated during the ‘one-two punch’ of the 1997-98 El Niño and storms of the following winter,” he says. Today, he adds, the community is a “classic example of ‘hot spot’ El Niño erosion. Normally during the next few years following an El Niño winter, we expect the beach sand to be carried back to the south by the ‘normal’ waves, but this has not happened yet at Neskowin, and it’s not clear why it hasn’t.”

Over the last decade, with support from Oregon Sea Grant and agencies such as the National Oceanic and Atmospheric Administration, scientists have been zeroing in on those subtle factors. Basic questions motivate them: How do coastal systems work? How do currents carry sand onto and off a beach, piling it up in some years and draining it away in others? Is sand accumulating on the coast or moving permanently into the deep ocean?

Just as importantly, they are providing communities like Neskowin with the knowledge to reduce property risks in the future. “We’re getting great data about the Oregon coast now. Compared to what we had 10 or 15 years ago, the observational data we have today are like night and day,” says Onno Husing, executive director of the OCZMA.

Citizens, elected officials and policymakers can see those data at the click of a mouse. Researchers regularly profile beaches from Gold Beach to Astoria and publish charts that show present and past sand heights relative to mean low and high water levels (see “Beach and Shoreline Mapping” at www.nanoos.org). They monitor wave heights and wave “run-up” on beaches. They estimate future flood risks and how many homes, roads and businesses are in harm’s way. And they meet with citizens to share the results.

Although the broad direction of changes over at least the last decade is clear, Ruggiero emphasizes that uncertainty casts a shadow over the likelihood that any home or community will suffer damage in the future. The range of estimates for climate change only adds to the difficulty of forecasting future risk.

Speaking of just one factor, increasing wave heights, he says: “Attributing it to climate change is very difficult. I don’t do that, but the bottom line is that the waves have increased over the last several decades, and that could be for a variety reasons. Any time you look way out into the future, uncertainty is huge.”

What is certain is that big waves will continue to hit the West Coast and attract sightseers to places like Neskowin, Rockaway and Depoe Bay. How coastal communities will adapt is an open question.

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Read a National Academy of Sciences report, Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future (2012)

One Response to “Surf’s Up!”

  1. infotechment says:

    Vert useful information, many thanks to the author.

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