Scientists on lookout for tsunami debris

By COLIN M. STEWART

Tribune-Herald Staff Writer

Debris from the March 2011 Japanese tsunami is now reaching Hawaii shores, and scientists expect that it will continue to wash up through the winter and into spring.

As of Friday, no sightings had been reported around the Big Island, but experts say they expect debris to arrive at beaches that typically see a lot of marine detritus, including Kamilo Beach in South Point. The area has been called “Plastic Beach” because of its propensity to collect plastic litter as it breaks off from the Great Pacific Garbage Patch and is caught by converging ocean currents and the trade winds.

A blue plastic container found floating in the ocean near Oahu’s Makapuu Point on Sept. 18 was the first confirmed piece of debris from the tsunami to be found in the state. On Friday, the Department of Land and Natural Resources announced that the state was working with federal partners to locate a 30-foot-by-50-foot floating dock that was last seen on Sept. 19 by fishermen off the north coast of Molokai.

“DLNR’s priority, with the critical help of the public and federal partners, is to re-find this large floating object, which is a hazard to vessels at seas and the wellbeing of our coastal resources,” said William J. Aila Jr., DLNR chairman. “We need to be able to track its movement to try to intercept and handle the dock at sea, and to prevent serious environmental damage if it should reach shore.”

The dock is believed to be identical to three others reported missing from Japan after the tsunami. Another of the docks came ashore on an Oregon beach in June. Items of debris were found washed up on beaches along the Pacific Coast of North America from Alaska to California this summer.

Shortly after the tsunami, scientists Nikoloai Maximenko and Jan Hafner with the University of Hawaii’s International Pacific Research Center in Honolulu generated a computer model predicting that the debris field would float north of the Hawaiian Islands and hit the mainland, before swirling down into the Great Pacific Garbage Patch. From there, they expected small pieces would break off and float toward Hawaii in the latter half of 2013.

Since those initial calculations, however, the scientists have updated their model to take into account the effects of “windage” on items that stick up out of the water as they float, Haffner said.

“Our first estimations of tsunami debris to arrive on the West Coast of North America were based only on ocean surface currents,” he said via email this week. “We did not consider the effect of wind on the movement of the tsunami debris. There are many different types of debris, some are sitting deeper in the water while others are rather floating on the surface. Floating type of debris is subject to force of wind more than debris flowing deep in the water. Later we revised our model and included this wind effect.”

The pair’s newest calculations account for the fact that Hawaii is now seeing pieces of debris arriving from Japan.

“We can expect the tsunami debris to keep arriving here for the next several months, through the winter and probably into the next year spring,” Hafner said. “However, we do not expect any massive amounts to end on Hawaiian beaches. Most likely it will be just a few pieces at a time. The most likely places to be affected by the tsunami debris are the same locations which already are receiving general marine debris, namely Kamilo Beach on Hawaii and Kahuku on Oahu, and, of course, many others.”

Most of the wind-driven type of debris ended up along the coast of the mainland, he said, while things driven more by currents could arrive here, including floating docks, derelict boats, and other things half-submerged in water.

As the debris continues toward Hawaii, a number of agencies have partnered to respond, including the DLNR, the Department of Health, the National Oceanic and Atmospheric Administration (NOAA), the U.S. Coast Guard and the U.S. Environmental Protection Agency. Marine debris may be reported via email to disasterdebris@noaa.gov or by calling the DLNR at (808) 587-0400.

“If possible, we request that a picture of the debris with a detailed description of the object, date found, location and finder’s contact information be sent to dlnr@hawaii.gov,” said a Friday press release.

Concerning the missing dock, the DLNR has requested that boaters, fishers and pilots be alert to the possible presence of the dock and to immediately report any sightings of the dock to (808) 587-0400.

NOAA announced Friday that it was continuing to assist with providing model trajectories for the possible movements of the dock by currents and winds, and had readied two satellite tracking buoys for state use, should the dock be located.

The Japan Ministry of the Environment estimates that 5 million tons of debris washed into the ocean following the tsunami, not the 25 million tons that was initially estimated. They further estimated that 70 percent of that debris sank near the coast of Japan soon afterward. Models and estimates completed by NOAA and UH revealed that some high-floating debris may have passed near or washed ashore on the Northwestern Hawaiian Islands as early as this summer.

“Because most tsunami debris was washed out to sea before the release of radioactive materials from the power plant and because of its extended exposure to the elements, it is highly unlikely that the debris would be contaminated,” reads the Friday release from NOAA.

However, the release added, the state Department of Health has been conducting shoreline surveillance since April 2011 in order to establish normal background radiation levels around the islands. It continues to conduct quarterly shoreline environmental surveys on Oahu, Maui, Kauai, and Hawaii Island. So far, those results have remained consistent with normal levels.

Email Colin M. Stewart at cstewart@hawaiitribune-herald.com.