Many of Maui's beaches are disappearing at an alarming rate. Can we stop the erosion before our economy and way of life crumble into the sea?
December 07, 2006
We like to think of our island's beaches as our playground. Kicking back on a blanket of warm golden sand while listening to the crescendo of crashing waves seems to dissipate whatever problems we might have into the air like spindrift off cresting white-water barrels. A great deal of Maui's economy—like mega-resorts and ocean activities—rests on these beaches as well.
Even children learn that building castles on sand is risky, and Maui is learning that now. Because of global warming and a host of man-made actions, Maui's beaches are eroding away at an alarming rate.
For more than a decade, Dr. Chip Fletcher, Professor and Chair of the Department of Geology and Geophysics at the University of Hawai`i at Manoa has been working to provide valid research to help planners and decision makers understand how to care for and help mitigate beach erosion issues around the state. His research is striking.
Between 1949 and 1997, West Maui, Kihei and the North Shore saw erosion rates averaging about one foot per year. That translates into a 20 percent loss in beach width or roughly five linear miles of beach completely lost. Considering environmental impacts—and especially if sea-level continues to rise—Fletcher believes that over the next 25 to 50 years, Hawai`i will see one beach after another disappear until there are only a handful left on each island.
"There is no easy or inexpensive solution to this problem," he says.
Derived from coral and seashells, Maui's sand is a precious natural resource. Broken off the reef from the impact of ocean waves or the munching of reef fish, these calcareous skeletons and shells become golden grains of sand. Taking millions of years to build a reef and the symbiotic ecosystem, sand derived from this source is finite.
"Reefs are simply not as prolific a source of sand," Fletcher says of Maui's narrow beaches. "Because of erosion, these skinny beaches are starving and are beginning to look anorexic."
Fletcher's work shows that in West Maui, the average beach width has narrowed by 25 percent. The greatest narrowing occurred in Alaeloa (38 percent), Honokowai (36 percent), Launiupoko (34 percent) and Hekili (35 percent). Since the end of World War II, West Maui has lost 2.8 miles of beaches, with the worst erosion at Kahana, Honokowai, Wahikuli, Lahaina, and Launiupoko.
There are several reasons for the steady disappearance of Maui's beaches. Hurricanes, tsunami inundation, waves and currents have all contributed to beach erosion.
There's the melting of the Greenland and the West Antarctic ice sheets and the warming of the atmosphere. Rising ocean temperatures are deteriorating Hawai`i's coral reefs, which support the diversity of marine life and are the source of our light-colored sand.
Then there's the rise in the sea level. Fletcher says globally, sea level has risen four to eight inches over the past century.
"But a pair of satellites that have been mapping the ocean surface for more than a decade and a half have recorded accelerations in the rate of sea-level rise," Fletcher says. "The latest sea level research in 2006 shows an average increase of global mean sea level to over 12 inches per century from 1993-2005. This rate is more than 50 percent greater than the average rate of the last 50 years."
Human manipulation of the beach—activities like sand mining and shoreline armoring—has also caused a dangerous imbalance in our shoreline's natural processes.
"The effects of rising sea level and coastal erosion do not necessarily threaten an active shoreline if humans do not tamper with the beach," Maui County Coastal Resources and Shoreline planner Thorne Abbott says.
In its natural state, the beach will migrate landward and erode the sandy upland area, says Abbott. Eventually, the sediment that is eroded from the upland will become part of active beach and the beach is maintained. "Unfortunately, man's actions to save land and private property interrupt this natural process of sand movement, depriving the system of needed sand and creating a deficit in the sand budget," Abbott says
During the 1970's and the 1980's, development on Maui's shoreline burgeoned. Along the West, South and North shores, houses, condominiums, hotels and timeshares began to crowd the coastline. To protect investments from the pulverizing force of the ocean, landowners built seawalls and revetments to try and halt erosion.
But this temporary "securing" of the beach has taken place at the expense of the adjacent beaches and communities. "Even in the late 1970's, government agencies recommended hardening the shoreline to respond to erosion crisis," Abbott says. "Today, we now recognize that seawalls and revetments can exasperate erosion on sandy shorelines."
Currently, the only means of shore protection activity supported by state, county and federal agencies is beach nourishment. "Placing high quality, low silt, clean sands at strategic times and at specific locations will compensate for a sand 'short-fall' when the natural source of the beach's sand is impounded by structures or its movement hindered by walls," Abbott says.
In other words, nourishing a beach requires more than dumping sand from anywhere onto the shoreline. To assure the health of the reef ecosystem, beach nourishment projects require clean sand similar in color, granule size and chemical make-up to what would naturally be found on the depleted beach. The sand should also be local—imported sand derived from a different source will stress the environment, and could kill the sea life that burrow near the shoreline.
Maui has two sources of compatible sand: the inland dunes located off the Central Valley and beach sand that has resettled on the ocean floor.
Maui's inland dunes are considered an easily accessible source of sand. But local concrete companies have largely scooped up these dunes for concrete production. Nearly mined to extinction, this resource now makes up the foundations of new buildings and roads—some on Maui, but mostly on Oahu. Today the companies Hawaiian Cement and Ameron are excavating the last undeveloped dunes in Maui Lani and Lower Waikapu.
Earlier this year, officials with Mayor Alan Arakawa's administration prepared the Maui Inland Sand Resource Quantification Study. Their goal was to quantify how many of the inland's golden grains are left. According to the report, the two companies send approximately 244,000 tons of sand every year to Honolulu for use in ready mix concrete, with another 74,000 tons used on Maui.
In 2004, 63 sand barges left Maui, another 96 in 2005 and an estimated 90 barges will shove off this year. If mining continues at this pace, the study concluded that our sand dunes would disappear entirely in just five to seven years. For that reason Arakawa proposed a possible moratorium. The Maui County Council is currently reviewing its legal options.
"I equate the loss of our sand resources with the loss of Hawai`i's `iliahi [sandalwood] trees," Maui County Environmental Coordinator Rob Parsons says. "This precious resource and corresponding ecosystems were depleted to nearly nothing in a few short decades."
In the 1800's loggers harvested Hawai`i's `iliahi forests to near extinction for the sandalwood trade with China. Maui's forests never recovered.
Getting to the second source of sand for beach nourishment requires dredging the ocean floor out to the offshore channels. But even that oversimplifies the logistics of such an operation: first, officials have to find the sand fields. Then, they need to test the area to see if the material is still pretty white sand or if it's become gray and dirty from silt, and plant and animal waste.
In the past, dredging sand has been considered too expensive when compared to mining inland dune sand. Considering that the inland dunes are now nearly depleted, as well as the cost of trucking the sand—including the wear and tear on our roads—many experts hope dredging may become the more cost-effective solution.
While workers have dredged sand from local boat harbors for beach nourishment, offshore sand dredging is new to Hawai`i. Dolan Eversole, Coastal Geologist at the University of Hawai`i Sea Grant College Program, is leading the state's first offshore dredging project using state-of-the-art offshore sand pumping technologies.
The starving, "anorexic" beach they want to plump up—Hawai`i's world famous Waikiki. Today, the beach is so narrow in places that the tourists are nearly stacked on each other to get a piece of it.
In November, workers vacuumed 10,000 cubic yards of sand off the ocean floor 2,000 feet off the coast of Waikiki beach, which they then used to replenish Kuhio Beach, which fronts some of Waikiki's most popular hotels. It's those hotels, built right on the shoreline, that explain why the beach has largely disappeared.
The dredging and placement of sand cost approximately $452,000, with an additional $20,000 spent on the follow-up water quality monitoring and environmental surveys. Officials will use the data obtained from this pilot project to establish appropriate environmental and design parameters, cost estimates, pumping system designs and production rates for future beach replenishment efforts.
"This project proves that the technology is available in Hawai`i," Eversole says. "I'm hopeful the Waikiki project can serve as an example for potential projects on Maui."
Even if the Waikiki replenishment proves successful, it may not solve our beach erosion problems. UH Professor Chip Fletcher believes the economy to support the tens of millions needed to build and maintain beaches is only found in a few locations around the islands. He thinks beach nourishment may only be a short-term solution to a long-term problem. "Do we want to keep our beaches for one, five or 50 years, and which beaches do we commit to?" he asks.
Fletcher believes the most effective long-term approach is for the county to identify healthy beaches on sandy coastal land that have not yet been developed, then buy the land to prevent hotels and houses going up.
"As the land erodes with sea-level rise, sand will be released and feed the beach, keeping it healthy," he says. "The initial cost of buying the land will be high, but ongoing costs will be negligible. Our grandchildren will thank us for making the investment in their future.
Fletcher believes counties should go back to the beach parks and try to bring them back to their original state. That means testing the land behind the beach to assure that it's sand-rich, as well as removing or redesigning the seawalls and building up the dunes behind the beach.
"It's odd how many of our beach parks are missing beaches," Fletcher says. "Every county has beachless beach parks. It's worth another look at these and asking if we can do a better job."
Fletcher doesn't believe the loss of our beaches will bring Hawai`i's tourism industry to a screeching halt. He says many tourists are content to stay at the lavish resorts that provide a simulated beach environment around their pools. The real problem, he says, is that the local community will suffer.
"As an ocean community, the loss of our beaches will mean loss of access to the ocean, the ability to race canoes, learning to surf and swim and the loss of those activities most of us like to do after work and on the weekends," he says. "Local life will be changed dramatically." MTW
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