Rising sea levels doom beaches, geologist warns

A scientist cites Ehukai as a site where erosion is taking a toll

Most of Hawaii's sandy beaches are eroding, and the rising sea level will only make things worse.

That is one of the key messages coastal geologist Dolan Eversole and land planner Sam Lemmo try to get over to people when they talk about Hawaii's shores.

"I bought the house and walk out in my beautiful yard and, 'Oh, my God, the coastline is 20 feet away,'" Lemmo said last week to a group of North Shore residents gathered in Sunset Beach Elementary's cafeteria.

Want To Know More? The Department of Land and Natural Resources' Office of Conservation and Coastal Land expects to offer a continuing series of public talks, with question-and-answer sessions, on all islands this year. The meeting schedule can be found at www.hawaii.gov/dlnr/occl/files/ Workshops/OCCL-07workshops.pdf. For more information, contact Dolan Eversole at 587-0321 or dolan.eversole@hawaii.gov. Books On Coastal Hazards Two handy reference works for those who own or are contemplating purchase of coastal property are: » "Natural Hazard Considerations for Purchasing Coastal Real Estate in Hawaii," by Dolan Eversole and Zoe Norcross-Nu'u. This free, 23-page booklet addresses coastal hazards, ways to respond to them and government and private agencies that deal with them, as well as insurance, design ideas and a list of useful Web sites. Available at the state DLNR's Office of Conservation and Coastal Land, Kalanimoku building, 1151 Punchbowl St., 587-0377, and also at county planning offices. The booklet is also online at www.hawaii.gov/dlnr/occl. » "Hawaii Coastal Hazard Mitigation Guidebook," by Dennis J. Hwang, is a 215-page, $20 reference work that goes much deeper into the subject, spelling out government and industry standards, different ways to design and plan coastal building projects, etc. It is for sale through the University of Hawaii's Sea Grant Program (call 956-7410), and limited copies are available at the DLNR. Coastal Hazard Legislation » House Bill 1391 and Senate Bill 1477: These companion bills in Gov. Linda Lingle's legislative package would require planning departments to factor in expected sea-level rise and the risks from coastal hazards such as erosion, storm inundation, hurricanes and tsunamis when looking at coastal development plans. » House Bill 1037: This bill, introduced by Rep. Pono Chong (D, Kaneohe-Kailua), would require new buildings to be set back from shorelines a minimum of 150 feet, versus the current guidelines, which begin at 20 feet and vary by county.

Homeowners there have a heightened interest in erosion this year, after summer erosion across the street at Ehukai Beach "was of particular magnitude," Eversole said.

One woman told Eversole that the distance of the ocean from her house has varied over the years, from "a football field away" to "right there."

Winter swells have brought back at least half of the sand scoured away last summer, so it looks like the area will recover, said Eversole, a University of Hawaii Sea Grant coastal geologist who is on loan to the state Department of Land and Natural Resources. But last year, some worried beachfront landowners were asking whether the state could move some sand to protect their properties.

That did not happen, but seeing the ocean move as close as it has been in a decade or more made North Shore residents receptive to learning about beachfront land use.

Eversole and Lemmo, the administrator of the DLNR's Office of Conservation and Coastal Lands, will be giving educational talks about coastal hazards on every island this spring.

A foot a year is the sandy beach erosion average for the state, Eversole said. Some are much more, some less, but "only a handful of beaches in the state are not eroding."

One slide in the duo's presentation shows the shoreline -- dividing sandy beach from grassy bluff -- running straight down the middle of a house on Kauai. A few more feet and the house will tip into the surf.

One doesn't have to debate global warming to realize that Hawaii's coasts are in peril, Eversole said. Sea-level rise statistics show that the ocean has been rising about an inch per decade worldwide, he said.

An inch might not sound like much, but over the years it can make a difference.

Eversole passed out copies of a paper published in the Jan. 19 issue of Science magazine. It projects that, based on global-warming predictions by the Intergovernmental Panel on Climate Change, the sea level will rise between a foot and a half to 4 1/2 feet by 2100.

"A foot to foot-and-a-half rise vertically has a tremendous impact horizontally," Eversole said, showing a slide of Waikiki with that amount of sea-level rise projected. Only a sliver of land remained above water between the Ala Wai Canal and the beaches.

"You could imagine about the same effects on Haleiwa and Waialua," he said.

And that's aside from storms, tsunamis, hurricanes or a phenomenon called mesoscale eddies, which raise sea levels for weeks to months at a time.

"We are extremely fortunate not to have had a tsunami in 40 years," Eversole said.

As the DLNR focuses more on educating people about how beaches work, the goal is "to balance coastal development with beach conservation," Lemmo said.

"Because there's no balance, that's why our beaches are disappearing," he said.

Some at last week's meeting are not convinced the North Shore is actually eroding.

"Most of our beaches have huge waves, moving massive amounts of sand away from and back to that beach," said North Shore resident and Realtor Richard Sterman.

But he gave the example of his own house on Ehukai Beach, which saw a huge change in beach size this year but did not lose any land mauka of the shoreline.

"Most North Shore beaches have fairly stable vegetation lines," Sterman said.

Whether that is proved out by a current scientific study remains to be seen.

Erosion varies widely from beach to beach and year to year, Eversole said. But the long-term trends can be mapped, as they have been on Maui.

Though one might expect the huge surf of winter to be the erosive factor for all the state's north shores, in a lot of cases it is milder summer swells that take away the sand, Eversole said.

One still-glaring example is a beachfront house in Waialua that has sandbags protecting it from perilously close surf.

"We expect it to recover," Eversole said. But the fact that the state approved temporary sandbags signals how close the surf got to the house.

The owner of the house did not return calls requesting comment.

Landowners' rights to protect their homes from destruction by the ocean has so far trumped concern about the eroding shoreline, Eversole and Lemmo said.

Their emphasis is on smart planning at shorelines that have not yet been developed. That is why they ask anyone who considers building near the ocean to take a hard look at the actual erosion of that particular beach.

Maui County's regulations for how close one can build to the shore are based on scientific studies done by a UH coastal geology team. Oahu and Kauai are being studied now and could adopt similar rules.

"The question is, Do you want a beach here in 50 years or something else?" Lemmo said.

"Hawaii's beaches are such a valuable, irreplaceable resource," he said. With no proactive steps to save them, "we are going to lose a lot of beaches over the next century."