A November nor'easter caused severe beach erosion and damage on Long Island's South Shore.

Erosion is the process by which large storms, flooding, strong wave action, sea level rise, and human activities wear away beaches and bluffs along coastlines. All beaches are affected by storms and other natural events that cause erosion; however, the extent and severity of the problem differs in different parts of the country, and so there is no one-size-fits-all solution.

In the U.S., coastal erosion is responsible for roughly $500 million per year in coastal property loss, including damage to structures and loss of land. To mitigate coastal erosion, the federal government spends an average of $150 million every year on beach nourishment and other shoreline erosion control measures.1 In addition to beach erosion, more than 80,000 acres of coastal wetlands are lost annually—the equivalent of seven football fields disappearing every hour of every day.2 The aggregate result is that the United States lost an area of wetlands larger than the state of Rhode Island between 1998 and 2009.3

Cliff erosion is a common storm-induced hazard along the West Coast.

While coastal erosion affects all regions of the United States, erosion rates and potential impacts are highly localized. Average coastline recession rates of 25 feet per year are not uncommon on some barrier islands in the Southeast, and rates of 50 feet per year have occurred along the Great Lakes. Severe storms can remove even wider beaches, along with substantial dunes, in a single event. In undeveloped areas, these high recession rates are not likely to cause significant concern, but in some heavily populated locations, one or two feet of erosion may be considered catastrophic.

Sea level rise will cause an increase in coastal erosion and the human response will be critical. If we choose to build hard structures to keep the shoreline position stable, we will lose beach due to scour. If we let the shoreline migrate naturally, we will be seeing increasing erosion rates especially in regions of the coast already dealing with starved sediment budgets and rapid shoreline migration. Increases in storm frequency and intensity in the future will also serve to cause increased coastal erosion. The U.S. Geological Survey has developed a Coastal Vulnerability Index that can help identify locations where coastal erosion may occur along undeveloped coastlines.

These photos show an area near Drew Point, along Alaska's northern coast. Taken on August 9, 2007, the top photo shows how ocean waves have undercut the land nearest the shore. Grassy turf extends out over a wave-cut notch. Taken on June 20, 2008, the bottom photo shows what often follows such undercutting: chunks of coastline tumbling into the sea.

Options for dealing with coastal erosion

In the past, protecting coastal shorelines often meant building structures like seawalls, groins, rip-rap, and levees. But as understanding of natural shoreline function improves, there is a growing acceptance that structural solutions may cause more problems than they solve.4 Structural projects affect natural water currents and prevent sand from shifting along coastlines to replenish beaches. Structural protective measures:

• are often expensive,
• can be prohibited under local and state regulations,
• can cause further erosion to adjacent beaches and dunes,
• require costly maintenance to ensure continued protection, and
• divert stormwater and waves onto other properties.

Recently, the U.S. Army Corps of Engineers has re-emphasized the need to consider a whole range of solutions, not simply structural solutions. They have also developed technical guidance to support adaptation to changing sea levels.

Effective strategies for dealing with coastal erosion

Many states have recently shifted towards non-structural shoreline stabilization techniques. Unlike structural projects, these protection measures enhance the natural ability of shorelines to absorb and dissipate storm energy without interfering with natural coastal processes.5 Some popular non-structural methods for controlling erosion include:

• beach replenishment,
• dune stabilization with fences and vegetation,
• wetland protection,
• habitat restoration,
• structure relocation and debris removal, and
• use of dredged material for beach nourishment.

It's important to note that it can be difficult to quantify the amount and reliability of wave attenuation and storm energy dissipation for a range of conditions that might be expected at a certain location.

Planning ahead

Effective shoreline management policies can help maintain the natural shoreline dynamics and preserve important coastal environments. So remember to do your homework before making any plans:

• Conduct erosion-related studies and investigations.
• Assess climate change vulnerabilities.
• Identify areas that are most likely to be affected.
• Engage and educate stakeholders.
• Develop warning systems and response plans to minimize human exposure to hazardous events.
• Establish appropriate building codes.
• Develop and implement adaptation strategies.
• Share lessons learned with other coastal managers.

Residual risk

Even with the implementation of coastal shoreline erosion and risk reduction measures, residual risk remains. Some areas are constantly in danger during severe storms. For some regions of the country, the more intense storms are predicted to increase in strength and frequency as climate continues to change, though the overall frequency of all storms may decrease. In some cases, the only way to prevent structures from causing harm may be to remove them entirely. After the structure has been removed, communities usually dedicate the land to public open space or transfer it to land trusts for protection. Such restoration projects can be highly cost-effective and provide benefits, including:

• buffering storm surges;
• safeguarding coastal homes and businesses;
• sequestering carbon and other pollutants;
• creating nursery habitat for commercially and recreationally important fish species; and
• restoring open space and wildlife that support recreation, tourism, and the culture of coastal communities.

• 1. NOAA Office of Ocean and Coastal Resource Management, 2013: Beach Nourishment: A Guide for Local Government Officials.
• 2. Dahl, T.E., and S.-M. Stedman, 2013: Status and trends of wetlands in the coastal watersheds of the Conterminous United States 2004 to 2009. U.S. Department of the Interior, Fish and Wildlife Service, and NOAA National Marine Fisheries Service, 46 pp.
• 3. Conathan, M., J. Buchanan, and S. Polefka, 2014: The Economic Case for Restoring Coastal Ecosystems. Center for American Progress and Oxfam America, 54 pp.
• 4. StormSmartCoasts, 2014: Only As A Last Resort: Flood and Erosion Control Structures.
• 5. StormSmartCoasts, 2014: Non-Structural Shore Protection.