Goldilocks of the Beach

Florida’s beaches draw millions of tourists each year, and coastal towns like Palm Beach have a great interest in protecting the beaches against erosion and sea-level rise.  They have experimented with various adaptation and reinforcement techniques, some more successful than others, but none is a permanent solution. 

In an administrative hearing on March 2, Judge Robert Meale rejected a beach renourishment project proposed by Palm Beach, criticizing both its harmful environmental impacts and the “worthless” engineering models that supported the project.  The suit was brought by an alliance of surfers and anglers, united in their interest to protect the dynamic beach ecosystem, offshore reefs, and sea turtle nesting habitat.  The judge’s ruling was notable not only for its harsh criticism of the project but also the clear environmental basis of his decision.

Beach renourishment is one of several techniques to address beach erosion, a naturally occurring process that will accelerate with climate change and sea-level rise.  Renourishment means taking sand from offshore or inland dunes and placing it on the eroded beach to widen the shoreline.  In theory, renourishment is a great solution – just track down the eroded sand and put it back on the beach.

As with many engineered responses to environmental processes, however, a huge gap exists between theory and practice.

When done correctly with matching sand, beach renourishment (without sand retention structures) is a preferred alternative to constructing “hard” structures, such as seawalls, groins, or jetties.  Those reinforcement techniques do not accommodate the natural migration of the beach, causing the beach to erode completely.

But in practice beach renourishment often does not work well either.  While renourishment may be effective at protecting coastal lands and preserving beach resources, it can have significant and long-term impacts on the beach ecosystem, from altering the fundamental composition of the beach to killing wildlife in the process of dredging the sand.  Moreover, renourishment projects often do not last as long as projected and require replacement sand every few years. 

One of the biggest challenges to any renourishment project is finding replacement sand that is similar in size, texture, and density as the eroded sand.  In Florida, the mismatch affects sea turtle nesting habitat in particular.  Five species of endangered or threatened sea turtles live in Florida waters and nest on Florida beaches.   In 2006, fully 20 percent of the state’s loggerhead nests were in Palm Beach county. 

Sea turtles are the proverbial Goldilocks of the beach – they need conditions to be just right, neither too hot nor too cold, for productive and successful nesting.  In this case, Judge Meale noted that if the new sand is too coarse, a sea turtle will not burrow because the sides will cave in, but that if the sand is too fine, oxygen will not pass through to the eggs.  In addition, the sex of the hatchlings is temperature dependent, so the color of the new sand may alter the heat transfer properties and thus the natural ratio of male to female sea turtles. 

The most effective alternatives to renourishment or hard beach-reinforcement techniques are less palatable to politicians and coastal property owners, but in light of continued beach erosion they must be considered.  In areas where there is no development, local zoning requirements should prohibit future developments.  In areas where there is development, development setbacks (particularly for rebuilding after a storm) should be implemented and strictly enforced.  More drastically, coastal communities should consider a landward retreat, an idea that is being considered in other countries.

Mike Sole, the secretary of Florida’s Department of Environmental Protection, now must decide whether to approve or deny Judge Meale’s recommendation.  In this case, the Secretary can play one of two roles: the crotchety bear that banishes Goldilocks from the beach or an empathetic bear that understands “just right” means exactly that.