When the shoreline starts moving toward the house, the instinct is to build a wall. About 350,000 structures in the United States sit within 500 feet of the shoreline, so coastal erosion — the loss of shoreline sediment — is a problem many coastal communities have to face. Shoreline armoring is one answer: physical structures built to protect the shore from erosion. It works, but it comes with costs.
Shoreline armoring along Wells Beach, Maine. Credit: NOAA.
What armoring is
To stabilize coastal land and protect homes and businesses, coastal managers and property owners build structures that hold back the sea and stop sediment from being lost. Seawalls, breakwaters and riprap are common examples.
The trade-off
Armoring has benefits and drawbacks. It can protect property. But by blocking the natural movement of sediment, it can also keep sandy beaches, wetlands and other intertidal areas from moving inland as the land erodes or the sea rises — eliminating habitat for marine life and beach for the public. Where stabilization is needed, the key is a method suited to the specific site, one that balances the needs of the public with the needs of the natural system.
Why shorelines erode
Coastal erosion is a complex, natural process that constantly reshapes the shore, but people can speed it up or slow it down.
| Natural factors | Human activities |
|---|---|
| sediment supply | beach nourishment (adding sand) |
| geology | dredging ports and coastal approaches |
| changes in sea level | building harbors and dams that trap sediment |
| waves, currents, tides and wind, which vary from place to place | shoreline armoring itself |
Sources
Based on "What is shoreline armoring?" from NOAA's National Ocean Service, a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from oceanservice.noaa.gov
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