When Beaches Vanish

Once I just had sand in my swimsuit. Now I have it on the brain too.

It began as I stood at the blunt western end of the Hawaiian island of Molokai, staring in horror at Papohaku Beach. Perhaps more correctly, staring in horror at what was left of it.   

One of the most perfect beaches I had ever seen, more than two miles of glorious sand and gently lapping waves, was pretty much gone. Spread before me in its place was a ravaged coastline studded with hard rock shelves and sharp coral boulders extending into a sea so ominously roiled it looked like a blender set to puree. There was almost no sand, walking on what was left of it reminded me of one those malevolent obstacle courses dreamed up for reality TV shows, and swimming was clearly out of the question unless life and limb had lost all meaning.

But the couple of times I’d seen Papohaku before it was such an ideal beach I was certain I heard Beethoven’s “Ode to Joy” swelling majestically in the background. The sand was soft and deep, the swimming was idyllic, and the almost complete lack of development gave the grand sweep of coastline a pristine, almost untouched quality so wonderful to gaze upon it put digitally enhanced travel posters to shame.

The Papohaku I knew had been jacked. What had happened to it?

IT WAS HERE SOMEWHERE

Look, I’m a beach guy. These things matter to me. I had to get to the bottom of Papohaku’s Jekyl and Hyde act. Why did a perfectly good beach disappear, and where did it go? Perhaps even more important, did a sinister code of silence (a sand omerta?) exist among shoreline resorts worldwide to keep a lid on the truth regarding the relative presence or absence of sandy beaches? I was on a roll. Wasn’t it the right of the vacationing public to know if a beach would be inviting and useful at the specific time one expected to be there, and whether swimming in the sea then would be a reasonable expectation and not an invitation to bodily harm?

I was buried in sandy righteousness. First, though, I figured perhaps I should make sure I wasn’t once again simply the victim of synaptic insufficiency.

Turns out, this time I wasn’t. Maui-based coastal geologist Rob Mullane, a Hawaii-based beach scientist confirmed that the beach I recalled indeed existed. “Papohaku is one of my favorite beaches in the world,” he said. “It’s one of the largest beaches in Hawaii and more often than not your footprints will be the only ones in the sand.”

FOLLOW THE SAND

 Yes, I whined, but why doesn’t it look like that now?  Mullane chuckled and told me that I remembered the summertime Papohaku. “It faces northwest so it’s subject to seasonal changes,” Mullane said. “It’s the first place waves coming from Alaska in the winter reach land, and there are no offshore islands and no reef to protect it. So the beach gets scoured.  In the summer, the waves comes from the south and the beach rebuilds.”

Seasonal beach changes weren’t limited to Papohaku, Mullane added. At Magic Sands Beach, on the Big Island outside Kailua-Kona, the sand vanishes so thoroughly it used to be called “Disappearing” Sands, a name local authorities apparently considered counterproductive from the tourism standpoint. “It’s an extreme case,” Mullane said. “During the high wave season, there’s very little sand there. It’s just lava and boulders. But in the summertime there’s a two-foot thickness of sand.”

Mullane said that even one of Hawaii’s best known and most popular beaches, Maui’s Kaanapali, goes through yearly cycles of plenty and paucity. “Kaanapali runs north and south, so in the winter the north end has a very strong seasonal change. It gets narrower in winter, and in the summer the southern swells bring the sand back so it widens again.”

 Brings the sand back? But where does it go?

“At Kaanapali, the sand moves along the coast, but in the case of Magic Sands, it actually moves offshore,” Mullane said.

Seasonality wasn’t just a Hawaiian phenomenon, he added. “Seasonal change isn’t only common to Hawaiian beaches, it’s common to all beaches,” he said.

DR. BEACH EXPLAINS

For wider perspective, I turned to everybody’s favorite academic, Dr. Beach. In real life, his name is Stephen P. Leatherman, but we all know him for the list of America’s top beaches he issues every year. “Whole beaches can disappear,” Leatherman said. “You say, my goodness, what happened? Where’s the beach? Well, it went into a big sandbar offshore.”

After politely declining to disclose whether he wears Tevas to his lectures, Leatherman deployed genuine science in explanation. The rough, short-period, storm-driven waves that occur everywhere in winter tend to scour the sand from the visible beach and deposit it offshore as much as 200 or 300 yards. But sometimes the sand instead moves to a different spot on the beach, as in the case with Kaanapali, or even to another beach nearby. In summer, gentle, long-period ground swells move the sand gradually back where it was to begin with. The process occurs with beaches worldwide, but among the most pronounced victims are in Hawaii and along the California coast, Leatherman explained.

 I had visited Papohaku before in summer, when the sand was at its most plentiful and the sea was its most tranquil. But I returned in winter, when the ocean’s wave energy arrives like a freight train from the North Pacific to pummel beaches with orientations like Papohaku and Kaanapali’s.

That’s when the swimming can turn ugly, too. “If there’s high enough wave energy to move the sand, then you’re apt to have more dangerous swimming conditions,” said Mullane. “You can get a pretty steep slope to the beach, and that can mean larger waves, strong offshore currents, and greater undertow. That can take people by surprise.”

TIMING THE SANDS

 So I asked Dr. Beach how a person could plan for the best possible beach. “Go in the summertime,” he said. “That’s definitely true for Hawaii and California, and it’s also true for a lot of other places, because that’s when the wave energy is less.”

With normal seasonal changes and no artificial barriers, the beach always returns. But human intervention can lead to the permanent sand loss and the steady retreat of a beach. In Florida and along the East and Gulf coasts, Leatherman said, beaches diminish seasonally but rarely disappear completely unless manmade objects like seawalls, groins, revetments and river dams have altered natural sand movement or replenishment. Some of Palm Beach, Florida’s cove beaches vanish in winter because of this, he said, and Miami Beach’s sand becomes harder and packed with coral chunks for the same reason.

Elsewhere, said Leatherman, receding shorelines have led to an alarming rate of beach loss in some places along the east and Gulf coasts. Some Louisiana beaches are retreating at the rate of 50 feet a year, he said, due mainly to far less of the Mississippi’s silt reaching them than has been the case in the past and the sinking of coastal land from the extraction of oil and water. “Louisiana is the beach erosion hot spot of the nation,” he said.

HAVE YOU SEEN THE KIDS?

In fact, said Leatherman, beach erosion is a national problem that plagues between 80 and 90 percent of the country’s coastline. Sometimes it’s of epic proportions. He said Cape Hatteras, South Carolina, has averaged 15 feet of beach lost every year for more than 150 years. And the southern coast of Nantucket Island is losing about ten feet of beach annually.

The Caribbean, he said, experiences some beach loss, but it isn’t drastic. “Beach erosion is occurring throughout the Caribbean, but it’s not a particularly severe problem,” he said.  However, hurricanes can decimate beaches there. Gilbert, George, Lenny and Jose’ all wreaked havoc in the Caribbean in recent years, along with Floyd in the Bahamas and Iniki on the Hawaiian island of Kauai.

Such extreme weather events can dump a beach’s sand too far out to sea or throw it too far inland to ever return. That means the sand is gone forever from the fragile beach system coastal scientists call the “sand budget”.  “Hurricanes can cause massive beach erosion,” said Leatherman. “It can take years for beaches to recover from hurricanes, and in some case they don’t come back at all.”

THAT’S WHERE SAND COMES FROM, VIRGINIA

 Beaches stripped by extreme weather events or because of human intervention usually must be replenished with sand from elsewhere, called “beach nourishment” by coastal scientists. For an island, that can be problematic. Sand can’t usually be mined from an island or scooped up from other beaches, so it must come from offshore sandbars. However, dredging is expensive and can harm underwater environments.

Still, sand had to come from somewhere to build beaches in the first place. Why not wait for nature to do the job again? The trouble is, that takes time, even eons.

“Marine creatures manufacture sand, or it comes down from rivers,” Mullane told me. For most islands, the primary source of sand is coral, either ground into grains by wave action or the nibbling of parrotfish over thousands of years. Rivers can also deposit silt and sediment along island shorelines, but it isn’t often the major source of sand as it is for land mass coastlines where no coral exists. Over time the soil washes away and what remains is sand. Wind and rain contribute too by helping coastline cliffs erode and crumble. It’s an agonizingly slow process.

NOT ON MY BEACH

And it’s a process humans are hindering. Many rivers are now dammed and cliffs are often armored to prevent erosion, both of which cut off the key sources of sand where corals don’t live. California’s building beach crisis is one example of what can occur when a shoreline’s natural sources of sand are throttled. 

But, agree coastal scientists, by far the worst enemies of both island and mainland beaches are the artificial barriers placed there for the very purpose of “protecting” them. These interrupt the natural flow of sand along the beach, concentrating it in some areas and stripping it from others. In Hawaii, where newspaper reports have cited the loss or narrowing of 25 percent of Oahu’s beaches and 30 percent of Maui’s, this has created acrimonious confrontations between proponents of science-based beach management and the owners of oceanfront property in fear of losing their land.

“There is abundant proof that seawalls kill beaches on shorelines undergoing chronic erosion,” wrote University of Hawaii geology and geophysics professor Chip Fletcher, a recognized expert on beaches, in a letter to the Honolulu Advertiser newspaper.

Maui-based Mullane said beach loss is “almost always found on beaches that have been armored with seawalls or revetments. Some of Maui’s beaches are eroding so fast that even if you have 150 foot setbacks, you’ll have problems in fifty years.”

I hope that never happens to Papohaku. Meanwhile, there’s comfort in now knowing that its magnificent sand makes a triumphal return from that big offshore sandbar every year.

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2 Comments

Filed under Beaches, Hawaii

2 responses to “When Beaches Vanish

  1. This is one beaching good piece. Keep it up Dick.

  2. Chris Barnett

    Finally, a blog that actually says something thoughtful, something worth reading, and not some blathering by a harebrained Hemingway wannabe-but-never-will-be.

    Haul out the quill more often Peachie

    CB

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