Coastal erosion is an integral part of natural beach processes. Beaches are not stagnant, but instead are dynamic systems that shift, migrate, fill and erode; sometimes taking and sometimes giving. While many coastal communities throughout the United States and around the world point to coastal erosion as the cause of their shrinking beaches, erosion really only becomes a problem when we build houses, roads and other structures too close to the water. Unfortunately that is how development has been occurring along our coasts, and we haven't given our beaches the room they need to naturally maintain themselves.
Compounding the erosion issues that many beaches face are sea level rise, storm damage, subsidence of land, and interruption of natural sources of sand caused by revetments and jetties. Faced with a steady inland migration of the ocean that may range from a few inches to several feet per year, coastal communities have limited options to deal with the situation. Many houses along the coasts of the United States have already been lost on eroding beaches.
The potential responses to coastal erosion include seawalls, beach fill, and managed retreat. Seawalls, rock revetments and other hard structures built to hold back the advance of the sea often fail and need to be rebuilt over and over again. This approach is not desirable for several reasons, not the least of which is that these structures inevitably lead to the loss of sand from beaches – sand trapped underneath and behind the seawall, and sand eroded directly in front and down drift of the seawall. Waterfront properties receive only a temporary respite, while public beaches are often lost for good.
Another approach is beach fill, also known as beach nourishment, whereby sand is typically dredged from a harbor or offshore source and pumped/placed/spread on a beach to widen it. Issues associated with beach fill include sand compatibility/quality, ecological effects, changes to the beach and offshore bottom contours, effects on wave quality, and damage to offshore reefs. In addition, these projects may be very costly and typically must be repeated every few years. Who pays for the project (Federal/state/local government? Beach town property owners? Only beach front property owners? Users of the beach?) is often a difficult issue to resolve. Coastal cities in Florida have already tapped out their sources of compatible off-shore sand from constant dredge and fill projects and are now looking to ship in sand from the Bahamas at an exorbitant cost.
That leaves the option of managed retreat.
Managed or planned retreat (also known as managed realignment) allows the shoreline to advance inward unimpeded. As the shore erodes, buildings and other infrastructure are either demolished or relocated inland. It can also involve setting back a line of actively maintained defenses to a new line inland of the original – or preferably to rising ground – and promoting the creation of intertidal habitat between the old and new defenses. This can either be a complete removal or a breach of the defence (dike, seawall, revetment, etc.).
Coastal managers realize that in many situations attempting to stop erosion through structural or non-structural solutions is a losing battle. Shoreline protection efforts and/or their repeated maintenance would be too costly and ultimately ineffective at preventing further erosion. A managed retreat approach typically involves establishing thresholds to trigger demolition or relocation of structures threatened by erosion. Therefore, this approach is frequently coupled with several other planning and regulatory techniques including: shoreline planning, to identify high-risk areas where this type of policy would be the only cost-effective, long-term solution; regulating the type of structure allowed near the shore to ensure that buildings are small enough and constructed in a way to facilitate relocation when needed; and instituting relocation assistance and/or buy-back programs to help with relocation costs or compensate property owners when their property becomes unusable. While the overall policy emphasizes retreat, a managed retreat approach may allow some erosion control measures using soft-stabilization techniques to prolong the life of shorefront buildings and other infrastructure for a limited, defined period of time. However, hard stabilization structures or repeated beach renourishment are generally not permitted.
This approach is usually less expensive then costly structural stabilization projects that may only be a temporary solution, especially in highly erosive areas. Managed retreat maintains natural shoreline dynamics and enables shoreline habitats to migrate inland as the shoreline erodes to prevent loss of wetlands and other intertidal areas. Surfrider Foundation's Beach Preservation Policy emphasizes managed retreat as an appropriate long-term strategy for dealing with coastal erosion, stating:
"In areas where erosion threatens existing coastal development, the Surfrider Foundation advocates appropriate long-term solutions that maximize public benefit. These include:
- Landward retreat of structures from dynamic shorelines"
In 2012 NOAA's Office of Ocean and Coastal Resource Management (OCRM) published a report How Coastal States and Territories Use No‐Build Areas along Ocean and Great Lake Shorefronts. The report looks specifically at where states and territories employ no-build areas (e.g., through setbacks, rolling easements, or zoning) along ocean and Great Lake shorefronts, typically on dry, privately owned land, to protect the public interest.
Needless to say, managed retreat is not often a popular option and can be politically difficult to implement, especially where significant development has already occurred. It may cause depreciation of shorefront property values or, in some cases, complete loss of property values.
However, managed retreat has been implemented successfully at several locations.
Perhaps the most famous example of managed retreat in recent years was the relocation of the Cape Hatteras Lighthouse 2900 feet inland in 1999. When constructed in 1870, the lighthouse was 1,500 feet from the shore. Protective measures to reduce the rate of beach erosion in front of the lighthouse provided a temporary solution, but by late 1987 the lighthouse stood only 160 feet from the sea and was in danger of collapsing. A 1988 National Academy of Sciences Study and a 1996 study conducted by several researchers at the North Carolina State University found that relocating the lighthouse was the only feasible option. Adding additional groins, sea walls and sand to the beach would be more costly and were only estimated to last 20 or 30 years. In 1999, after several years of debate and lawsuits aimed at blocking relocation, the National Park Service successfully moved the lighthouse back 2,900 feet over the course of 23 days at a cost of $9.8 million. See also here and here.
Earlier lighthouse relocations were the move of Highland Lighthouse (pdf) (commonly known as Cape Cod Light) approximately 450 feet back from an eroding cliff in July-August 1996 and moving Nauset Lighthouse in Eastham, Cape Cod, Massachusetts, 300 feet back from the edge of a sixty-foot high eroding cliff in November 1996.
A similar issue currently exists with the Montauk Point Lighthouse in New York. The Army Corps of Engineers is proposing to expand the rock wall that surrounds Montauk Point. Concerned with increased erosion of adjacent beaches and lack of sand at down drift beaches, Surfrider Foundation's Eastern Long Island Chapter is trying to convince authorities to investigate the feasibility of moving the lighthouse back away from the eroding cliffs to protect it for centuries to come.
A very early example of managed retreat occurred at Coney Island, New York. In 1888 the beach became so badly eroded in front of the Brighton Beach Hotel that waves threatened the structure. To save the 500 foot long, three story hotel that weighed 6,000 tons, workers jacked up the entire hotel, placed it on 120 rail cars, and eased it inland six hundred feet. Six locomotives in two teams of three each moved the building so gently that not a pane of glass was broken nor a mirror in a room was cracked.
A small number of managed retreat projects have been undertaken in the UK, mainly along the Essex coastline. The first deliberate attempt at managed retreat in the UK was on a small island located in the Blackwater Estuary in Essex. The Northey Island project, organized by the National Trust (the landowners of the site), the Environment Agency and English Nature involved breaching and lowering a seawall to encourage salt marsh development on its landward side. Aided by high sedimentation rates the scheme has been successful, with a viable salt marsh community now established at the site.
An example of a coastal development that is ripe for relocating inland (and almost was) is The Riggings condominium development in North Carolina. The development in Kure Beach obtained permission to install a wall of sandbags in 1985. In 2008 (23 years after installation) the sandbags were still in place and a majority of the complex's 48 homeowners had rejected a $3.6 million federal grant that would have helped them relocate their oceanfront condominiums across U.S. 421. The grant would have dedicated oceanfront land the complex is currently on as parkland. In January 2008 the CRC denied the homeowners' request for another extension of their sandbag permit.
A similar situation exists at the Wild Dunes Resort in Kiawah Island, South Carolina where the property owners are trying to hold out with sandbags until an estimated $9.9 million beach fill project can be funded and implemented – now scheduled for completion by the end of July 2008. Property owners will pay a negotiated civil penalty of $18,000 for littering the coast and marshes with tens of thousands of small sandbags that washed away in storms in spring 2007.
Following are two managed retreat case studies in California, one implemented and one in the process of being implemented. In addition, Surfrider Foundation's San Francisco Chapter has been working with many other stakeholders for several years to develop and implement a response to erosion problems at Ocean Beach that involves managed retreat. Read more on that project here and here.
Pacifica State Beach
In San Mateo County, California, the City of Pacifica had long battled chronic coastal flooding and beach erosion. For decades, the city had employed structural stabilization techniques to armor Pacifica State Beach and channelize San Pedro Creek. Despite these earlier stabilization activities, the City continued to face three main shoreline management issues: flooding of homes and businesses; erosion of Pacifica/Linda Mar State Beach; and maintaining habitat for the steelhead trout in San Pedro Creek.
In 1982, a major flood damaged more than 300 homes. One home was eventually lost, and two homes and a restaurant remained threatened by storm surges and erosion. Therefore, the U.S. Army Corps of Engineers and the City's Flood Control Committee supported proposals to further harden and channelize the creek to reduce the risk of flooding.
At the same time, community members were also concerned about on-going erosion at Pacifica/Linda Mar State Beach - a popular surfing location. The surfing community, led by Pacifica's mayor, favored shoreline restoration and argued that shoreline armoring was accelerating long-term erosion at the community's beach.
Further complicating the issue, San Pedro Creek supports a native population of steelhead trout. The California Coastal Conservancy and other partners therefore argued for restoration of the lower channel and creek mouth to improve habitat for steelhead and other species.
In the early 1990s the City of Pacifica, the California Coastal Conservancy, and the Pacifica Land Trust decided to collaborate to work toward a managed retreat strategy that combined "soft" stabilization techniques to enhance steelhead habitat, reduce flooding threats and preserve the sandy beach, with the removal of vulnerable structures along the beach. During the 1990s, the City of Pacifica partnered with the California Coastal Conservancy, the California Department of Fish and Game, the Army Corps of Engineers, and the State Water Resources Control Board to expand and enhance the tidally influenced wetlands at the creek mouth and restore more than 1900 feet of eroding creek banks. This restoration both enhanced steelhead habitat and achieved 100-year flood protection for the nearby community. The wetland project also cost the community significantly less than other proposed flood control measures because it required less physical construction.
To address the remaining flood threat to homes and businesses, the City also removed the most vulnerable structures. In 2002, the City partnered with the Pacifica Land Trust and the California Coastal Conservancy to purchase two homes and their surrounding acreage for $2.2 million. They demolished and removed the homes and excavated concrete, rubble, asphalt, reinforcing steel, and tires. They also delivered 4,000 cubic yards of sand to rebuild dunes and restore four acres of beach and the nearby estuary. The city plans to relocate the one remaining shoreline structure—a Taco Bell restaurant -- to the other side of Highway 1 as part of a planned retreat strategy.
The end result of all this work is that flood hazards have been reduced, the wetland habitat is functioning, and the use of the recreational beach has increased.
Creative partnerships at the local and state level helped leverage the public support needed to implement a project that cost millions of dollars and took a decade to complete. Support of local government leaders, particularly the mayor, helped finance the up-front expenses for the ongoing project. Finally, a planned retreat strategy was made more politically viable because project partners had the capital necessary to purchase threatened structures outright.
Surfers' Point, Ventura
The City of Ventura is facing on-going erosion at Surfers' Point, a popular surfing spot, adjacent to the mouth of the Ventura River. A California State Park bike path along the shoreline and an adjacent County Fairground parking lot, have also experienced frequent damage from erosion. Since the mid-1980s the Surfrider Foundation has been advocating for relocating the bike path inland, to prevent the future need of a seawall and destruction of a famous surf break. However, to protect the Point, the City decided to place boulders above the mean high tide line along its upper end. The project ended up exacerbating erosion further down the coast and the Fairground parking lot and bike path have continued to erode into the ocean; in some places more than 60 feet of land have been lost. When the City applied for a permanent permit for the rock revetment, the California Coastal Commission denied their request but recommended that the parties involved should work together to resolve the issue.
Therefore, in 1995, a working group was formed which included representatives from the City, County Fairgrounds, California Department of Parks and Recreation, the Commission, the Ventura Chapter of Surfrider Foundation, and other interested parties. The California State Coastal Conservancy facilitated the group. While "managed retreat" was a favored strategy, the group disbanded a year later because they could not reach a consensus. The County Fairgrounds did not agree to a managed retreat approach as it would have reduced the number of parking spaces for the Fairground.
Nonetheless, Surfrider continued to advocate for a planned retreat strategy. A few years later, the former chairman of the Ventura Chapter of Surfrider was elected to the Ventura City Council, providing further support for a "managed retreat" option, and discussions over what should be done with Surfers' Point resumed. Another working group was created. In 2001 the group reached a consensus for a "managed retreat" project that included:
- Relocating the bike path and public parking lot more than 60 feet further inland.
- Removing existing rip rap
- Restoring the area to a more natural beach habitat
- Continuing to provide adequate parking for beach goers and the Fairground
- Providing for on-going beach renourishment
- Preserving public access to the area via Shoreline Drive
- Advocating for the removal of the Matilija Dam to increase sand supplies to the beach
As of summer 2005, the initial planning and design process and environmental documentation for the project had been completed. The City of Ventura allocated one million dollars of U.S. Department of Transportation's TEA-21 funding for the design and relocation of the bike path. The total construction cost was estimated to be $3.8 million and the City was pursuing funding for the remaining costs. In addition, the California Coastal Commission approved a permit for a renourishment project that includes a five-year plan for opportunistic beach replenishment at Surfers' Point.
Project design was completed in 2008. An updated estimate placed total construction costs at $8.1M. Increases were the result of general inflation in construction costs. A significant portion of the cost is cobble to rebuild and protect the shoreline. A cobble source was found from a County Flood Control project. Approximately $1M in possible cost-cutting measures were identified by leaving abandoned pipes in place, reducing landscaping costs, and limiting grass-pave to high use areas.
The City of Ventura has a federal transportation grant of $1.5M for the bike path. California's Ocean Protection Council members toured Surfers' Point as well as Matilija Dam in late February 2008.
Construction on this project finally began in Fall 2010 and Phase 1 construction was completed in July 2011.
See also Surfers' Point Task Force and Ventura River Ecosystem.
Often, the initial response to shoreline erosion is to build a seawall. Because managed retreat has not been a widely employed approach to shoreline management, it has been difficult to convince others that planned retreat might be the best economic and environmental solution for their erosion problems. Adopting a managed retreat policy at Surfers' Point has been successful because it began at a grassroots level. The Ventura County Chapter of the Surfrider Foundation has continuously championed this approach for two decades and highlighted the benefits of the option to the City Council and general public. The project was also successful, because it involved all major players in the planning process. Although the process took time, and was aided by a change in leadership in one agency, a consensus was reached that managed retreat was the best alternative.
The video report Swept Away from KCET in Los Angeles compares three different responses to sea level rise and coastal erosion - shoreline armoring at Broad Beach in Malibu, the Surfers Point managed retreat project in Ventura and a head-in-the-sand total denial from a local politician.
Online Managed Realignment Guide (U.K. and Europe)
Pacifica State Beach Managed Retreat, Beach and Estuary Restoration, Philip Williams and Associates
“Relocation of the Highland Lighthouse, North Truro, MA” by Joseph J. Jakubik (pdf)
Surfer's Point Project Description, Philip Williams and Associates
“The Search for Sand Is No Day at the Beach”, Charles Passy, New York Times, September 16, 2007 (as printed in boston.com)