State of the Beach/State Reports/WA/Beach Erosion
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Less than 1% of Washington's shoreline is critically eroding, according to the report "State Coastal Program Effectiveness in Protecting Natural Beaches, Dunes, Bluffs, and Rock Shores," (T. Bernd-Cohen and M. Gordon), Coastal Management 27:187-217, 1999. However, Washington does lay claim to a spot with the most rapid erosion on the US Pacific coast. Washaway Beach, Cape Shoalwater, has been eroding an average of 100 feet per year for a century. This news report from September 2016 provides a discussion of the erosion and the difficult choices faced by property owners in the area.
The southwest Washington ocean coast (~2.4 % of Washington's marine shorelines), backed by dunes and a broad coastal plain, is largely accretional with pockets of erosion which cycle between times of accretion and times of erosion driven partly by El Niño climate variability, and/or complications caused by nearby bay mouth jetties. These beaches are fed by sediments from the Columbia River basin and distributed by the Columbia River plume north up the coast. In recent decades the rate of accretion has slowed largely due to impoundment of those Columbia Basin sediments behind dams throughout the basin, as well as other possible factors. An example of an area that is now experiencing substantial erosion is Cape Disappointment State Park. Beachside areas once targeted for campground construction have been removed from the planning process because of the erosion. Park managers have also decommissioned sewer ponds because of fears that the ocean might erode into them. Researchers at Oregon State University predict that by 2020, the shore areas for about six miles north of North Head may retreat between 100 and 300 meters.
The northwest Washington coast (~3.8 % of marine shorelines), largely stable and backed by cliffs with a few pocket beaches, lies within Olympic National Park and five Indian reservations, and is therefore outside the coastal management jurisdiction of the State of Washington. Vertical land movement uplift exceeds the rate of sea level rise, resulting in a net negative sea level change, thus minimizing the effects of wave erosion on the coast.
Washington's inland marine waters of Puget Sound and the Strait of Juan de Fuca (~81 % of marine shorelines) are largely backed by low banks and bluffs; accretionary landforms such as spits are rare and mostly small. The rocky shores of the San Juan Islands are stable. The bluffs and low banks are erosional, with episodic erosion incidents at any particular place occurring every few decades; long-term average erosion rates for the most part amount to only a few tenths of a foot per year. This erosion material is considered essential to maintaining the Puget Sound beaches. Episodic landsliding in this area is driven largely by soil saturation during especially wet winters, usually La Niña winters. Beaches in this area are fed largely by eroded materials from adjacent or nearby bluffs, with river-borne sediments playing a minor role in beach maintenance. Vertical land movement subsidence exacerbates sea level rise thus hastening the movement of landslide sediments through the drift cells and into deep water.
The balance of Washington's marine shorelines (~13%) consists of offshore islands, ocean coast bays, and other areas not readily characterized. Only 3-4% of Washington's Pacific Ocean coastline has dry sand at high tide.
Erosion “hot spots” are located along the beaches in Southwest Washington. Erosion rates at Cape Shoalwater have been over 100 feet per year. Other critical erosion spots include Grays Harbor South Jetty, Ocean Shores (north of the Grays Harbor North Jetty), and Fort Canby State Park (now named Cape Disappointment).
Erosion rates for Pacific County vary dramatically. The Pacific County regions that experienced accretion from the 1950s to 1995 include Grayland, Leadbetter Point, Ocean Park, and Long Beach. The Cape Shoalwater and Fort Canby regions experienced mean erosion rates of 23.1 ft/year and 6.4 ft/year, respectively. Washaway Beach is famous for having vacation houses fall into the ocean. Erosion has been happening here for more than a century. A lighthouse that stood for nearly 80 years was among the first structural victims back in 1940. At times Washaway Beach has lost 100 feet a year.
The 2006 Assessment indicates that there are significant differences between erosion problems on the Pacific Ocean coast and the Puget Sound coast. Episodic erosion is largely associated with the Pacific coast during El Niño winters when higher than normal sea levels aggravate the normal winter beach erosion cycle. Chronic erosion is largely associated with the Puget Sound, where a combination of sea level rise, subsidence, and shoreline armoring lead to beach lowering and shoreline retreat.
During the past century most of the southwest Washington coast was characterized by accretion. Erosion was localized. During the 1997-98 El Niño winter storms however, a series of events (erosion at Cape Shoalwater, a jetty breach at Westport, erosion at Point Brown, and erosion at Fort Canby State Park) increased awareness of the potential for erosion along the state's southwest coast. Subsequently, a return to accretion patterns has resulted in much of that erosion being "back-filled."
In a study released in February 2017, U.S. Geological Survey scientists and their colleagues document how the 2015-16 winter featured one of the most powerful El Niño climate events of the last 145 years. Investigating 29 beaches along the U.S. West Coast from Washington to southern California, researchers found that winter beach erosion was 76 percent above normal, by far the highest ever recorded. If severe El Niño events such as this one become more common in the future as studies suggest, this coastal region will become increasingly vulnerable to coastal hazards, independently of projected sea level rise. The authors assessed seasonal changes on 29 beaches along approximately 2000 kilometers (1243 miles) of the U.S. West Coast. Surveying the beaches included making 3-D surface maps and cross-shore profiles using aerial LiDAR (light detection and ranging), GPS topographic surveys, and direct measurements of sand levels, combined with wave and water level data at each beach, collectively spanning 1997-2016. The full report, “Extreme oceanographic forcing and coastal response due to the 2015-16 El Niño,” was published in the journal “Nature Communications.” More.
In January 2010 a news release from Oregon State University stated:
A major increase in maximum ocean wave heights off the Pacific Northwest in recent decades has forced scientists to re-evaluate how high a “100-year event” might be, and the new findings raise special concerns for flooding, coastal erosion and structural damage. The new assessment concludes that the highest waves may be as much as 46 feet, up from estimates of only 33 feet that were made as recently as 1996, and a 40 percent increase. December and January are the months such waves are most likely to occur, although summer waves are also significantly higher.
In a study published online in the journal Coastal Engineering, scientists from Oregon State University and the Oregon Department of Geology and Mineral Industries report that the cause of these dramatically higher waves is not completely certain, but “likely due to Earth’s changing climate.”
Using more sophisticated techniques that account for the “non-stationarity” in the wave height record, researchers say the 100-year wave height could actually exceed 55 feet, with impacts that would dwarf those expected from sea level rise in coming decades. Increased coastal erosion, flooding, damage to ocean or coastal structures and changing shorelines are all possible, scientists say.
“The rates of erosion and frequency of coastal flooding have increased over the last couple of decades and will almost certainly increase in the future,” said Peter Ruggiero, an assistant professor in the OSU Department of Geosciences. “The Pacific Northwest has one of the strongest wave climates in the world, and the data clearly show that it’s getting even bigger.
The study, "The impact of the 2009-10 El Niño Modoki on U.S. West Coast beaches", published in The American Geophysical Union's "Geophysical Research Letters" on July 9, 2011 was led by the USGS in collaboration with the Oregon Department of Geology and Mineral Industries, University of California-Santa Cruz, Washington Department of Ecology, Oregon State University and Scripps Institution of Oceanography. The authors took advantage of up to 13 years of seasonal beach survey data along 148 miles of coastline and tracked shoreline changes through a range of wave conditions. The following is from a USGS press release.
"The stormy conditions of the 2009-10 El Niño winter eroded the beaches to often unprecedented levels at sites throughout California and vulnerable sites in the Pacific Northwest," said Patrick Barnard, USGS coastal geologist. In the Pacific Northwest, the regional impacts were moderate, but the southerly shift in storm tracks, typical of El Niño winters, resulted in severe local wave impacts to the north-of-harbor mouths and tidal inlets. For example, north of the entrance to Willapa Bay along the Washington coast, 345 ft. of shoreline erosion during the winter of 2009-10 destroyed a road.
Erosion continues to be an issue in Westport, however. The City of Westport declared an emergency at Half Moon Bay and Westhaven State Park on October 14, 2003. They passed a resolution allowing the immediate construction of a seawall, which reads, in part:
- "...is authorized to exercise powers vested under Section 1 of this resolution in the light of exigencies of an extreme emergency situation without regard to time-consuming procedures and formalities prescribed by law."
A "Final Environmental Assessment, Half Moon Bay Transition Gravel and Cobble Placement, Westport, Washington" was released in by the US Army Corps of Engineers in November 2003. This document presents a "preferred alternative" to deal with erosion problems in Westport, which consists of the placement of 40,000 tons (27,000 cubic yards) of 12-inch minus gravel and cobble material along approximately 1,000 linear feet of beach in the southwest corner of Half Moon Bay. The document states that "Barring an increase in the frequency of severe winter storms, this interim measure should provide adequate erosion protection for the next 5 years without a need for placement of additional material. The material placed would all be less than 12 inches in diameter, with between 50-85% by weight less than 3 inches." EPA submitted a comment letter on this project. More recently (January 2009), the Corps of Engineers prepared a presentation outlining alternatives for dealing with erosion at this location. Read more.
Work completed as part of the Southwest Coastal Erosion Study (SWCES) (also see here) has provided detailed information about sedimentation and circulation within Columbia River Littoral Cell, a segment of shoreline that includes southwest Washington and northwest Oregon. A general conclusion from this work is that changes along the southwest Washington coast can be attributed to a decrease in sediment supply. Discussions about how to address these problems on a regional basis are currently underway. Numerous SWCES publications on coastal erosion exist and many can be accessed on-line.
The Pilot Coastal Observatory for the Estuaries and Shores of Oregon and Washington Project (part of Northwest Association of Networked Ocean Observing Systems - NANOOS) gives an overview of shoreline erosion throughout much of the states. Beach profiles from several years are available here. Erosion data could be extracted from these beach profiles.
Beaches and Bluffs of Puget Sound provides a good summary of conditions of beaches in Puget Sound and the effects of shore stabilization measures.
Ecology has also published Coastal Bluffs and Seacliffs on Puget Sound, Washington, a 2004 report detailing the status of knowledge about Puget Sound coastal bluffs.
Landsliding is a major concern along Puget Sound shorelines. Landsliding is largely associated with heavy winter rains and steep slopes. The 2006 Assessment notes that more than 30% of the Puget Sound shoreline is susceptible to landsliding. Extensive damage from landslides during 1997-98 included the deaths of a family of four in their Bainbridge Island home, and greater than $30 million worth of losses in Seattle.
A wealth of information on Puget Sound landslides can be found at here. Among other things, this site features slope stability maps for the counties that ring the Puget Sound. These maps are part of the coastal zone atlases, which contain information on coastal geology, slope stability, flooding, sand and gravel resources, critical habitat, coastal drift inventory, and land cover/land use information. Publications on managing drainage on coastal bluffs, controlling erosion using vegetation, and tips for buying, building, and maintaining property along the Puget Sound shoreline, are accessible via this great site.
Ecology has compiled an inventory of Coastal Landsliding on Puget Sound: A Review of Landslides Occurring Between 1996 and 1999. Washington Department of Ecology Publication 01-06-019. Puget Sound slope stability mapping is also a feature of the online Washington Coastal Atlas.
The Washington Department of Natural Resources, Division of Geology is another source of information on beach erosion and coastal hazards in Washington.
The Heinz Center's Evaluation of Erosion Hazards, conducted for the Federal Emergency Management Agency, studied the causes of coastal erosion hazards and proposed a variety of national and regional responses. The study, published in April 2000, concentrates on the economic impacts of erosion response policies and the cost of erosion itself to homeowners, businesses, and governmental entities.
The report notes that for much of the latter half of the twentieth century, Washington State experienced seasonally punctuated and locally confined "hot-spot erosion" along its open-ocean shoreline, especially on either side of jetties built by the U.S. Army Corps of Engineers to protect inlets and the entrances of harbors. More frequently, the state had to deal with the unpleasant side effects of too much sand: the obstruction of the ocean view by growing dunes; "drowning" of houses, roads, and other infrastructure under sand; extension of access roads to the beach; and property rights issues around the newly created land. In the late 1970s, however, researchers noted that the shoreline accretion rates had begun to slow, and by the late 1980s the trend seemed to have reversed. Erosion became more common, even if still confined to a number of hot spots.
One of these erosion hot spots was discussed above - north of the Grays Harbor jetty in the city of Ocean Shores. Ocean Shores is a destination resort and retirement community of some 3,000 year-round residents, 10,000 part-time residents, and up to 60,000 visitors during peak summer weekends. The city awoke to the growing erosion threat in the late 1990s. During an El Niño winter, erosion had eaten into the city's southern end, the prime location for the homes of new arrivals who wanted to live and retire in the county's fastest-growing coastal community. Erosion was perceived as a big problem after several severe winter storms began to threaten a $20 million to $30 million condominium complex as well as a significant portion of the city's infrastructure located behind the primary dune. Although both the state and city recognized shoreline protection, wave action, erosion, and flooding as coastal management challenges, neither was really prepared to confront the emerging crisis with an explicit and well-thought-out erosion management strategy, and neither had the necessary funds to implement such a strategy. In a race against time, spurred by El Niño years with severe winter storms, a flurry of action was initiated to find an acceptable short-term and feasible long-term solution. The condo owners organized to privately fund, and more effectively lobby for, emergency protection of their investment. Subsequently, a two-tiered stone revetment (locally known as a wave-bumper) was permitted and built in front of the condos, albeit on the public beach. In addition, private consultants and several coastal communities lobbied the U.S. Congress and state legislature for funds to study and develop short- and long-term management responses to the erosion problem.
The governor convened a Task Force on Coastal Erosion to develop statewide recommendations, and coastal communities signed an inter-local agreement to coordinate lobbying and management efforts. Local and state agencies launched a major public education and awareness-raising campaign through workshops, public meetings, the local press, and improved collaboration between local and state agencies. Ocean Shores conducted a general environmental impact study (GEIS)—first with the help of consultants, then increasingly in collaboration with state agencies, the USACE, and the independent Battelle Memorial Institute—to determine the city's long-term management strategy. A strong effort was mounted to solicit public input through a Citizen's Involvement Committee as well as policy and technical advisory committees. The report was published in 1999.
General Erosion Data Reference Documents
The Heinz Center's Evaluation of Erosion Hazards, conducted for the Federal Emergency Management Agency (FEMA), studied the causes of coastal erosion hazards and proposed a variety of national and regional responses. The study, published in April 2000, concentrates on the economic impacts of erosion response policies as well as the cost of erosion itself to homeowners, businesses, and governmental entities.
A NOAA website that has graphs of sea level data for many coastal locations around the country over the last 40 to 50 years and projections into the future is Sea Levels Online.
NOAA Shoreline Website is a comprehensive guide to national shoreline data and terms and is the first site to allow vector shoreline data from NOAA and other federal agencies to be conveniently accessed and compared in one place. Supporting context is also included via frequently asked questions, common uses of shoreline data, shoreline terms, and references. Many NOAA branches and offices have a stake in developing shoreline data, but this is the first-ever NOAA Website to provide access to all NOAA shorelines, plus data from other federal agencies. The site is a culmination of efforts of NOAA and several offices within NOS (including NOAA’s Coastal Services Center, National Geodetic Survey, Office of Coast Survey, Special Projects Office, and Office of Ocean and Coastal Resource Management) and other federal agencies to provide coastal resource managers with accurate and useful shoreline data.
A related site launched in 2008 is NOAA Coastal Services Center's Digital Coast, which can be used to address timely coastal issues, including land use, coastal conservation, hazards, marine spatial planning, and climate change. One of the goals behind the creation of the Digital Coast was to unify groups that might not otherwise work together. This partnership network is building not only a website, but also a strong collaboration of coastal professionals intent on addressing coastal resource management needs. Website content is provided by numerous organizations, but all must meet the site’s quality and applicability standards. More recently, NOAA Coastal Services Center has developed a Sea Level Rise and Coastal Flooding Impacts Viewer as part of its Digital Coast website. Being able to visualize potential impacts from sea level rise is a powerful teaching and planning tool, and the Sea Level Rise Viewer brings this capability to coastal communities. A slider bar is used to show how various levels of sea level rise will impact coastal communities. Completed areas include Mississippi, Alabama, Texas, Florida, and Georgia, with additional coastal counties to be added in the near future. Visuals and the accompanying data and information cover sea level rise inundation, uncertainty, flood frequency, marsh impacts, and socioeconomics.
Erosion Contact Info
- Doug Canning, WDOE. Surfrider 2003 State of the Beach report survey response.
|State of the Beach Report: Washington