Humans reduce wave erosion through a combination of physical barriers, natural restoration, and strategic land-use planning. These approaches range from massive concrete seawalls to planting marsh grasses along the shoreline, and the best choice depends on the coastline’s geography, budget, and long-term goals. Most modern coastal management uses several methods together rather than relying on a single fix.
Hard Structures That Block Wave Energy
The most visible erosion defenses are engineered structures built from rock, concrete, or steel. These fall into a few categories based on their position and purpose.
Seawalls and revetments run parallel to the shore and act as a shield between waves and the land behind them. They absorb or deflect wave energy so it doesn’t reach buildings, roads, or other infrastructure. Revetments are sloped surfaces, often made of stacked rock, while seawalls are more vertical and rigid.
Groins and jetties extend outward from the shore, perpendicular to the waterline. Their job is to interrupt the sideways flow of sand along the coast (called longshore drift) and trap sediment on the “upstream” side. Jetties also stabilize inlets to keep navigation channels from shifting.
Breakwaters sit offshore, either above or below the waterline, and force waves to break before they reach the beach. This allows sand to accumulate in the calmer water between the breakwater and the shore.
All of these structures work, but they come with a significant tradeoff. By trapping sand in one place or deflecting wave energy, they starve neighboring stretches of coastline. A well-documented pattern called “flanking” occurs at the edges of protected zones: the beach just beyond a revetment or jetty often becomes narrower and erodes faster than it would have without the structure. In Thailand, for example, jetties built at Cha-Am beach caused erosion further down the coast, which then required its own revetments, which pushed erosion even further along. This cascading effect is one of the main reasons coastal engineers increasingly look beyond hard structures alone.
Soft Engineering: Working With Sand
Soft engineering uses the coast’s own materials to rebuild and reshape the shoreline rather than armoring it with concrete. These methods are less disruptive to natural processes and often more flexible, though they require ongoing maintenance.
Beach nourishment is the most common approach. Sand is dredged from offshore or transported from inland sources and deposited directly onto an eroding beach. The wider beach absorbs more wave energy before it reaches anything vulnerable. The scale of these projects can be enormous. In late 2024, the U.S. Army Corps of Engineers awarded a $72 million contract to place two million cubic yards of sand (the equivalent of 200,000 dump trucks) along 26 miles of Myrtle Beach, South Carolina. The cost had risen considerably from the previous nourishment cycle in 2018, reflecting how expensive it is to keep repeating the process as waves gradually carry the new sand away.
Beach scraping uses heavy machinery to redistribute sand that’s already within the beach system, reshaping dunes and berms without importing new material. Sand fencing is a simpler, cheaper tool: rows of semi-permeable fencing trap wind-blown sand to build up protective dunes naturally over time. Neither method adds sediment to the system, so they work best in areas that still have a reasonable sand supply.
Sediment bypassing addresses a specific problem. When jetties or channels interrupt the natural flow of sand along the coast, downstream beaches lose their supply. Bypassing systems use dredging or specially designed structures called weir jetties to move sand around these obstacles, mimicking the natural sediment-sharing process that the inlet would handle on its own.
Living Shorelines
Living shorelines use plants, shellfish, and other natural materials to absorb wave energy and hold soil in place. NOAA describes them as incorporating elements like marsh vegetation, oyster shells, sand, and rock. Unlike a seawall, a living shoreline can actually become more effective over time as root systems spread and organisms grow.
A typical project might include planting salt marsh grasses along the waterline, installing fiber mats or bio-logs to hold soil while plants establish, and constructing oyster reefs offshore to serve as natural breakwaters. Those oyster reefs are surprisingly effective. Research published in Ocean Engineering found that when a reef’s height relative to the water depth reaches a certain threshold, it can cut the energy of transmitted waves by more than half. The primary mechanism is wave breaking: the reef forces waves to crest and collapse before they reach shore, the same principle behind concrete breakwaters but with the added benefit of creating habitat for fish and filtering water.
Living shorelines work best in relatively sheltered environments like estuaries, bays, and tidal creeks. On high-energy open coasts with large storm waves, they’re often combined with harder elements like rock sills for added protection.
Setback Zones and Land-Use Planning
Sometimes the most effective way to reduce erosion damage is to keep people and buildings away from the edge. Coastal setback zones are regulations that prohibit permanent construction within a certain distance of the shoreline. The Mediterranean Protocol on Integrated Coastal Zone Management established a 100-meter setback as the standard buffer to protect settlements from coastal processes. Romania goes further, with its coastal law prohibiting permanent buildings within 50 to 150 meters of the shoreline depending on local conditions.
Setbacks don’t stop erosion itself, but they eliminate the need to fight it in those zones. Instead of spending millions to armor a stretch of coast, the shoreline is allowed to migrate naturally. This preserves beaches, wetlands, and dune systems that would otherwise be squeezed between rising seas and immovable infrastructure.
Managed Realignment
Managed realignment takes the logic of setback zones a step further. Rather than maintaining existing defenses in their current position, coastal managers deliberately move the defense line inland to a more sustainable location. The UK government describes it as a strategic option for improving the overall efficiency of flood and coastal defense systems.
In practice, this can mean breaching an old seawall to allow a low-lying area to flood naturally, creating new salt marsh that buffers the coast. It’s a difficult sell politically because it means giving up land, but it reduces long-term maintenance costs and creates the kind of natural habitat that absorbs wave energy on its own. It tends to be used in areas where the cost of maintaining hard defenses has become unsustainable relative to the value of the land being protected.
Choosing the Right Approach
No single method works everywhere. High-value urban waterfronts with dense infrastructure often rely on seawalls and revetments because the cost of losing buildings far exceeds the cost of construction, even with downstream erosion effects. Rural or ecologically sensitive coastlines are better suited to living shorelines, managed realignment, or simply enforcing generous setback zones.
The clearest lesson from decades of coastal management is that erosion is a system-wide process. Fixing one stretch of beach often shifts the problem somewhere else. The most effective strategies account for this by combining several approaches: a nourished beach backed by restored dunes, with living shorelines in sheltered areas and setback regulations preventing new construction too close to the water. The goal isn’t to stop the ocean, which is ultimately impossible, but to work with coastal processes enough to protect people and property while keeping the shoreline functional.