How long does managed retreat last

The alternative to protecting the coast is to allow nature to take its course, but to still have some control over what happens.

Although the land owners will have to be compensated for the loss of their land, managed retreat is still much less expensive than protecting the area. In the UK managed retreat is often the prefered solution when sea levels are rising and the challenge of defending the coast is becomming more and more difficult.

Isostatic readjustment after the last Ice Age, and rising sea levels due to climate change pose problems for existing defences that were designed to cope with lower tides. On the Jersey Shore, the emphasis has been on building higher dunes to mitigate the problem of coastal hazards threatening human infrastructure. However, as the coastal scientists point out, dunes and other beach features have a tendency to migrate landward.

As sea levels rise, this natural migration will accelerate. Options that involve working with these natural processes rather than trying to control them involve a longer-term approach and, as we have seen, can be controversial. We will look at some examples of places where these alternative methods have been employed using the principles of managed retreat or managed realignment, which are in contrast to the more reactionary approach of rebuilding structures in place and protecting them with dunes and other engineered lines of defense.

Managed retreat or managed realignment is a coastal management strategy that allows the shoreline to move inland, instead of attempting to hold the line with structural engineering.

At the same time, natural coastal habitat is enhanced seaward of a new line of defense. These include:. The report looks specifically at where states and territories employ no-build areas e. This Handbook collects examples, case studies, and lessons learned from successful and unsuccessful attempts at managed retreat in the hope that their lessons can inform future efforts to limit the exposure of communities to coastal threats. In , a study by University of Delaware examined federal homeowner buyouts across the US.

Over the course of FEMA's voluntary 30 year buy-out program, more than 40, at risk homes have been purchased to make room for flood plain restoration or open space, in over 1, counties in 49 states all states except Hawaii. Key findings include:. State Efforts to Encourage Managed Retreat In the wake of the destruction caused by Hurricane Sandy in October , coastal managers in New York, New Jersey and other states are re-thinking their options for dealing with future major storms and future sea level rise.

New York offered coastal homeowners in certain areas a buyout program to incentivize moving away from the coast and turning that land into greenspace intended to provide protection from future storms. Former New York City mayor Michael Bloomberg has spoken in favor of limited retreat as well as the development of natural buffer zones.

In , the California Coastal Commission updated their Sea Level Rise Guidance document with the most up to date science on projection scenarios.

Additionally, the Coastal Commission introduced a draft Residential Adaptation Policy Guidance which heavily encouraging the use of managed retreat, living shorelines and avoidance of hard armoring. The Commission argues against relying on sea walls for fear that they would make sandy beaches disappear under rising ocean water. It may cause depreciation of shorefront property values or, in some cases, complete loss of property values. Additionally, the loss of value associated with managed retreat policies and regulations is highly likely to result in subsequent lawsuits.

Hino et al summarizes the main impediments to managed retreat, which include:. 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 2, feet inland in When constructed in , the lighthouse was 1, 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 the lighthouse stood only feet from the sea and was in danger of collapsing.

A National Academy of Sciences Study and a 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 only estimated to last 20 or 30 years. See Surfrider articles on the project from the summer of , including a project update and victory post. Earlier lighthouse relocations were the move of Highland Lighthouse pdf commonly known as Cape Cod Light approximately feet back from an eroding cliff in July-August and moving Nauset Lighthouse in Eastham, Cape Cod, Massachusetts, feet back from the edge of a sixty-foot high eroding cliff in November 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.

In April the U. Unfortunately, this report fails to consider managed retreat and instead calls for feet of "revetment protection" with 15 ton armor stone. More on this. A very early example of managed retreat occurred at Coney Island, New York. In the beach became so badly eroded in front of the Brighton Beach Hotel that waves threatened the structure. To save the foot long, three story hotel that weighed 6, tons, workers jacked up the entire hotel, placed it on 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. A similar but larger project that has been equally successful is the Medmerry Managed Realignment Project , completed in November A new, 7km sea wall was constructed 2km inland of where a stretch of the old shingle wall was removed and the area in-between is now intertidal marsh. Three hundred and fifty homes, two resorts and a water treatment plant are now protected from a one thousand year flood.

In addition, the community now has a massive new wildlife refuge for wading birds, and endangered species like the water vole. Explore the Collection ». The student materials are available for offline viewing below. Downloadable versions of the instructor materials are available from this location on the instructor materials pages.

If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty and this box. Or you can download these pages in several formats that you can include in your course website or local Learning Managment System.

Learn more about using, modifying, and sharing InTeGrate teaching materials. What is Managed Retreat? Activate Your Learning Objective: Investigate alternative methods for non-structural shoreline hazard mitigation, including managed retreat and multi-layered defenses.