Restoring Natural Dunes to Enhance Coastal Protection
Barrier islands in New Jersey are like a ribbon of sand along the coast. The linear islands originally formed as ocean waves and currents pushed sediments from the ocean floor into beaches and dunes after the last ice age. Over the centuries, undisturbed dunes migrated back and forth across their beaches, moving inland or beachward as prevailing winds removed sand from one side of the dune and deposited it on the other.
Stressors and impacts
As homes and businesses crowded New Jersey’s shore in the early- to mid-20th century, development encroached on the back (inland) side of natural dune systems, narrowing the width of beaches and reducing the area that could supply sand to either side of the dunes. Roads and other structures effectively pinned down the formerly dynamic system. Over the years, the height and protective abilities of the dunes diminished.
As glaciers melt and warming seawater expands, rising sea levels increase the risk of flooding along all coasts, especially during storms. When Hurricane Sandy hit New Jersey’s beach in October 2012, neighborhoods that sit inland of developed beaches received the full brunt of the storm’s waves and storm surge. In other areas, where natural beach dunes were still in place, damage was less pervasive.
Natural dune systems = natural (green) infrastructure
Some shore communities are now recognizing the benefits of preserving or enhancing the natural infrastructure that dune systems offer. Instead of pursuing costly engineering solutions or beach replenishment programs to address their vulnerability, some towns work with nature to rebuild dunes. Planting beach grasses and installing and maintaining sand fences can help hold sand in place. Sand fencing helps capture wind-blown sand and also controls pedestrian traffic to protect fragile dune vegetation. Modifying paths to the beach so they are angled rather than perpendicular to the beach is another dune-enhancing strategy; this change reduces the opportunity for either wind or waves to move sand from the dune directly inland.
Natural infrastructure projects along coasts and rivers across the country illustrate a variety of ways that nature-based infrastructure can help mitigate the effects of extreme weather and rising sea levels. These projects offer multiple benefits including cost-effectiveness, ability to continue adapting to changing conditions, improving habitat for fish and wildlife, and inspiring strong local support.