Summer tides increase likelihood of Hawaii shoreline erosion

HONOLULU – Hawaii’s big waves and high tides will make shoreline erosion and flooding likely this summer, officials said.

A University of Hawaii geologist has predicted a “regional anomaly” is likely to produce tides 2-4 inches (5-10 centimetres) higher than levels noted on charts, The Honolulu Star-Advertiser reported Monday.

There will be 36 days with peak high tides above 2.2 feet (0.67 metres) in June, July and August, according to the National Oceanic and Atmospheric Administration.

An anomaly involving cyclical high water levels and Pacific winds will cause levels higher than those predicted by NOAA. Combined with big waves, these high tides make shoreline inundations and erosion likely, said Dolan Eversole, a geologist and coastal processes specialist for the Sea Grant program at the University of Hawaii at Manoa.

The highest tide will be 2.6 feet (0.79 metres) on July 31, plus another 2-4 inches due to the anomaly, said Eversole, who serves as a technical adviser to the Waikiki Beach Special Improvement District.

The extra inches of water can pose problems, said Charles Fletcher, professor of earth sciences at UH Manoa’s School of Ocean and Earth Science and Technology.

“This water level Dolan (Eversole) identified is something to worry about: Erosion may be worse this summer than expected, particularly on southern shores,” Fletcher said.

“All this variability is superimposed on a long-term rise of sea water levels because of global warming,” he said.

NOAA has announced a 70% chance that mild El Nino conditions will continue through the fall, producing warmer ocean temperatures and a 70% chance of an above-normal hurricane season in Hawaii.

___

Information from: Honolulu Star-Advertiser, http://www.staradvertiser.com