In the face of eroding beaches and losses to coastal habitat and local economies, we are left with essentially three options: retreat, armor, or replenish.
There are a number of planning and policy mechanisms designed to prevent the evolution of such a dire situation. But in cases where much of our shoreline is already developed and facing erosion risks every day, the management strategies are really quite limited.
Retreat. In this approach, we concede our shoreline (along with all of its associated property and infrastructure) to the natural processes of coastal erosion. We move buildings as far away from the shoreline as possible on each lot, move them to different inland parcels, or abandon them entirely. Although more practical for areas with low development intensity, retreat is usually not a feasible alternative in highly developed coastal areas since considerable investments have already been made in property and infrastructure, or due to real estate limitations on landward relocation of buildings.
Armor. Sounds like a call to arms, but shoreline armoring is merely a way of holding ground against coastal erosion. Coastal structures such as revetments, seawalls and bulkheads are designed to reduce or reflect the erosive force of waves and protect the land behind them. The disadvantage of these structures is that they do not protect beaches, and so valuable habitat and recreational areas are still lost to erosion. Jetties and groins can capture some of the sand and preserve the beach, but these structures typically interrupt the longshore transport of sediment and cause other erosion problems downdrift in the absence of a sufficient sand supply.
Replenish. This strategy positively benefits sediment transport and renews the sand supply to reduce erosion of the coast. Beach nourishment periodically replenishes beach sand in order to maintain beach profiles and advance the shoreline seaward. When implemented with compatible sediments, nourished beaches act as a buffer to protect the land from the erosive forces. Use of sand in this sacrificial way means that beach nourishment projects are an exercise in stewardship and must be periodically re-nourished. Possible sources of beach nourishment materials include dredging projects (beneficial use of dredged material), inland sand sources, and offshore sand borrow areas.
Further discussion of beach erosion responses is available from NOAA’s Coastal Services Center.
A relatively new approach to managing coastal erosion is the Living Shoreline. This hybrid technique implements bank stabilization and habitat restoration techniques to create a natural buffer that absorbs wave energy and reduces coastal erosion while maintaining physical and ecological processes.