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by Chelsea Hale, student writer

In the last two to three years, Hawai‘i’s popular white-sand Kailua Beach has been dramatically affected by shoreline erosion and beach loss. Though Kailua Beach usually loses its shoreline at about a rate of one to three feet every year, in these past couple of years, Kailua Beach erosion rates have been as high as eight feet per year, which experts believe to be one of the highest rates in the state.
“ I believe beach loss will have a significant impact on Hawai‘i’s culture,” said Christopher Conger, a local shoreline specialist.
“ From native Hawaiians to transient tourists, most people who are in Hawai‘i look to the ocean and the coastline for activity and identity. The loss of beaches, coastal access, coastal recreation, and cultural uses will have a profound impact on Hawai‘i,” he said.
“ In the late 1990s, several studies showed that 25 percent of O‘ahu’s sandy beaches had been lost or narrowed, and 33 percent of Maui’s beaches had been degraded. That trend has only continued,” Conger said.
Dolan Eversole, coastal geologist, says that Hawai‘i beaches are showing some visible signs of erosion.
“ Typical signs of coastal erosion are narrowing of the beach, eroded land with trees leaning or falling in, and failure of shoreline structures as they are bypassed by the shoreline moving forward,” he said.
According to Conger, one of the most visible signs of erosion at Kailua Beach is the “sandgrabbers” or hollow-tile bricks along the coastline that allow waves to wash sand through.
“ The majority of beaches in Hawai‘i are eroding with the exception of a few stable or accreting bays,” Eversole said.
Though all Hawai‘i beaches are losing shoreline to erosion, Eversole says localized short-term erosion appears to especially accelerate on the North Shore of Maui and Kailua Beach.
“ In Kailua the erosion is centered near the Kaelepulu Stream mouth and extends to either side of the stream,” Eversole said. “Ironically the rest of the bay in Kailua is accreting.”
“ We can expect that erosion will be most susceptible on the southern end,” said geologist Dr. Floyd McCoy. “Kailua is a big beach, some parts erode and others build out.”
Although a definite cause for erosion and beach loss remains elusive, experts believe that global warming and a subsequent rise of sea level could be a factor.
“ Erosion is usually the result of wave energy environment, sediment supply, and sea level,” Conger said. “Hawai‘i has many eroding beaches, and some experts predict that erosion will accelerate with rising sea levels.”
This increase in sea level, Eversole says, causes the shoreline to migrate landward causing coastal erosion.
“ As global temperatures rise, land-locked ice melts,” Conger said. “This water is new mass for the oceans and raises sea level. An equally important issue is the increased temperature of the oceans. Currently, thermal expansion is considered responsible for up to half the modern sea level rise.”
While sea level may contribute to the noticeably worsening erosion, Conger says that each location is different and therefore each area eroding may have different factors that contribute to the erosion.
As Kailua Beach’s southern shoreline shows significant erosion, there is concern from experts that erosion will continue to progress up the beach. Conger says there is a fear that Kailua will mimic Lanikai, which has lost most of its sandy shore to the ocean.
“ Coastal erosion is like the cancer of coastal hazards. You don’t really notice anything extreme until it’s too late,” Conger said.
Though coastal erosion may only be noticed far too late, coastal experts are still working together with both the government and private agencies to conserve and protect Hawai‘i’s diminishing beaches.
“ The first priority we are working towards is to not build so close to the shoreline to begin with,” said Eversole. “This would make a big difference in new developments and is something within the power of local landowners.”
McCoy, who currently is helping to educate the public on the importance of not building along the shoreline, says it is crucial to give space for our beaches to grow.
“ There must be a wide coast for our beaches,” he said. “The beach is where ocean meets the land, and if the ocean rises on the land, new beaches will form. Unfortunately, where the new beaches will form, is where houses and roads that never should have never been put there will be.”
In the past, attempts have been made to slow or stop erosion by building seawalls in front of these properties. But according to Conger, while these seawalls were built to prevent erosion, they have also sped beach loss along Kailua’s southern shoreline.
Eversole states, the Department of Land and Natural Resources and UH are working to identify “legacy” beaches that have some chance of being preserved in the future where development would be restricted near the shoreline.
Conger says that a beach management plan is currently being drafted for Kailua Beach. This plan he says, is being created by private consultants, but funded and overseen by the UH Sea Grant College and the DLNR.
“ This will hopefully be the first step in proactively managing the coastal resources as an integrated, spatial unit,” said Conger. “Healthy coasts with intelligent development strategies are also safe coasts for coastal communities,” he added.
As experts and government agencies work to preserve our beaches, they have found that while beach restoration is a fast fix, it is costly and only viable in certain areas.
“ Erosion cycles are natural phenomena,” said Conger. “You can minimize their impacts or stop their progress if you are willing to spend the time, energy, and money.”
“ Retreat is the long-term solution if we want to retain sandy beaches,” said Eversole. “We are a long ways from implementing this, but I see it as the only way we will be able to protect our sandy beaches for our grandkids.”
“ I would expect, and this is my personal opinion, that the erosion will continue to spread to the north and we will see beach narrowing and long-term erosion into the coastal dune and coastal plain,” Conger said Though erosion is a natural process that can never be completely reduced, Eversole said it can be adapted to by retreating from the coast.
“ I don’t see any way to prevent erosion, but we do have the ability to adjust to erosion by not developing the shoreline, not allowing the trapping of sand behind shoreline structures,” said Eversole.
Conger expects that there will be a handful of healthy beaches where sediment supply is able to outpace long-term sea level rise. He also believes there will be a number of protected beaches identified as worth saving by agencies or private individuals. “But I also expect that by 2100 Hawai‘i will have few beaches left, as private property rights continue to outweigh resource protection capacity,” Conger said.
In 10 years, Eversole says the condition of Kailua Beach will all depend on if the current erosion cycle continues, stops, or is mitigated by placing more sand in the system.
“ I feel our only hope of having sandy beaches in the next 50 years is to identify important legacy beaches where we retreat from the coast and ensure a natural sandy system is preserved,” said Eversole.

 

 

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