In the United States, coastal erosion is responsible for “roughly $500 million per year in coastal property loss, including damage to structures and loss of land,” according to the U.S. Climate Resilience Toolkit.
Coastal erosion is defined as intensifying effects of sea-level rises, king tides and storm surges. Coastal erosion means the loss or displacement of land, or the long-term removal of sediment and rocks due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other effects of storms. It is the wearing away of cliffs and beaches by the sea.
Simply stated, the U.S. land mass is shrinking. In order to understand this ongoing phenomenon, it’s important to define some key terms.
How Long Is the US Shoreline?
According to the National Oceanic and Atmospheric Administration (NOAA), the official length of the U.S. shoreline is 95,471 miles. Shoreline mileage of the outer coast includes offshore islands, sounds, bays, rivers, and creeks to the head of tidewater or to a point where tidal waters narrow to a width of 100 feet.
Using this definition, the U.S. coastline extends on the West Coast from the southern tip of California up to the northern edge of Washington state, and from the Gulf of Mexico at Texas around the southeast and up to Maine. At 33,904 miles, Alaska has the most shoreline of any U.S. state, and when measured linearly, is almost as long as the entire Pacific coastline. In addition, American Samoa has 126 coastal miles and Puerto Rico has 700 miles.
How to Mitigate Coastal Erosion
The shoreline is shrinking; as a result, vital infrastructures are at risk, literally drowning essential ecosystems. Hurricanes bring strong waves, heavy rains and high winds that erode affected coastlines. And as these storms intensify, so does coastal erosion because natural buffers are lost, shorelines disappear and storm surges reach farther inland.
Some cities have resorted to filling eroded areas with sand, notably New Orleans, Louisiana; Sandy Hook, New Jersey; and Galveston, Texas. Storm-drain gates are another mitigation technique for other cities to prevent seawater from backing up into the water system.
An eroding coastline not only affects the land, but also the shipping and fishing industries, as well as off-shore wind farms. Like any natural ecosystem, the coastal environment is transitory; change is natural and unforgiving.
By changing natural systems, coastal erosion is altering our climate, melting mountain glaciers and ice sheets, and slowing down the Gulf Stream. In addition, a rapidly increasing population and our relentless consumption of natural resources are taking a toll on the natural world.
Should Coastal Erosion Be Categorized as a Natural Disaster?
Several U.S. cities have declared coastal erosion to be a natural disaster in order to receive additional government disaster relief funding. A consequence of living in a flood-prone area is increased insurance costs or worse; homes in those areas become uninsurable. For example, according to the Federal Emergency Management Administration (FEMA), “Just one inch of water can cause $25,000 of damage to your home.”
But a century-plus of sustained coastal development, buoyed by federal flood insurance, is significantly advancing the dynamic through population growth and, in some cases, overcrowding further straining the environment.
The Mitigation of Coastal Erosion Is an Ongoing Effort
One of the chief challenges in eroded areas is the need to rebuild. The immediate answer is to stop all construction along the coastline and relocate homes away from flood zones. State and municipal governments must take action to slow the growth of new construction permits in those areas.
“Permitting construction along these vulnerable areas has only put them at more risk, says Federico Del Monte, president of the Sociedad Puertorriqueña de Planificación (Puerto Rican Planning Society). He told the Global Press Journal that “The immediate answer is to stop all construction along the coastline and relocate homes[away] from flood zones.” A public hearing to consider a moratorium on construction in vulnerable areas was scheduled for June 3.
Another way to treat erosion is to construct a rock wall. That includes dredging, placement of the sand, removal of small rocks, and granite boulders from the beach as well as dune stabilization and access paths. In addition, dewatering mechanisms are needed to address both large- and small-scale erosion-protection projects.
Coastal Erosion Is a Global Problem
Several countries that have experienced large-scale coastal erosion are taking action. Between 1990 and 2016, nearly 34% of India’s coastline experienced varying degrees of erosion, according to a report by India’s Ministry of Earth Sciences at the National Centre for Coastal Research.
Puerto Rico tops the list of areas most affected by climate change in the last 20 years, according to the 2021 Global Climate Risk Index. Scientists anticipate an increase in the frequency and intensity of storms and hurricanes, which will only exacerbate the erosion problem on the island.
Environmental Factors Impact the Coast
Increasingly frequent and intense cyclones and storms, spurred by climate change, have called into question the long-term effectiveness of geotubes in mitigating fallouts such as coastal erosion and saline water ingress. The geotubes are also known as geobags, containers that are hydraulically filled with a slurry mix of sand and water and used for sludge dewatering projects because of their simplicity and low cost. Sandbags are a temporary solution that have been used for over 75 years to combat coastal erosion.
Seawalls installed to protect the shoreline have only worsened the erosion problem. What is needed are concerted efforts to mitigate the expanding coastal erosion challenges, including identifying the extent of natural erosion processes, as evidenced by collapsed arches and eroding bluffs. Also, we need to firmly set the future direction for the use of beaches, pedestrian paths and roadways.