Coastal Erosion to Double by Mid-Century in Hawaii as Sea Levels Rise

The sandy beaches of Hawai'i may be beautiful, but they're also succumbing to coastal erosion. Now, scientists have taken a closer look at sea level rise and the effects of this erosion, and have found that the coastal erosion of Hawai'i's beaches may actually double by mid-century.

The researchers examined several different sites around Hawai'i for this latest study. Then then modeled the shoreline, accounting for accretion of sand onto beaches and long-term sediment processes.

Like the majority of Hawai'i's sandy beaches, most shorelines in the 10 study sites for this latest research are currently retreating. If beaches were to follow current trends, an average of 20 to 40 feet of shoreline recession may occur by 2050 and 2100, respectively.

"When we modeled the future shoreline change wit hthe increased rates of sea level rise (SLR) projected under the IPCC's 'business as usual' scenario, we found that increased SLR causes an average 16-20 feet of additional shoreline retreat by 2050 and an average of nearly 60 feet of additional retreat by 2100," said Tiffany Anderson, the lead author of the new study, in a news release. "This means that the average amount of shoreline recession roughly doubles by 2050 with increased SLR, compared to historical extrapolation alone."

Currently, the resulting erosion hazard zones are overlain on aerial photos and other geographic layers in a geographic information system. This could be a valuable tool for identifying infrastructure and property exposed to future coastal erosion.

"With these new results government agencies can begin to develop adaptation strategies, including new policies, for safely developing the shoreline," said Anderson.

The findings are published in the journal Natural Hazards.

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