70% of Beaches Eroding on Kauai, Oahu, and Maui

Aerial photograph of Kaanapali Beach. (credit: Andrew Short, University of Sydney).

By Sonia Isotov

An assessment of coastal change over the past century has found 70% of beaches on the islands of Kauaʻi, Oʻahu, and Maui are undergoing long-term erosion, according to a US Geological Survey (USGS) and University of Hawaiʻi (UH) report released today.

Of the three islands, Maui beaches experienced the highest rates and greatest extent of beach erosion with 85% of beaches eroding and 71% of beaches eroding on Kauaʻi and 60% of beaches eroding on Oʻahu.

Scientists from the USGS and the School of Ocean and Earth Science and Technology (SOEST) at UH studied more than 150 miles of island coastline (essentially every beach) and found the average rate of coastal change – taking into account beaches that are both eroding and accreting – was 0.4 feet of erosion per year from the early 1900s to 2000s.

William Aila, DLNR Board Chair. Courtesy of Hawaii News Now.

Of those beaches eroding, the most extreme case was nearly 6 feet per year near Kualoa Point, East Oʻahu.

“The inevitable fate of the Hawaiian Islands millions of years into the future is seen to the northwest in the spires of French Frigate Shoals and the remnants of other once mighty islands, ancestors of today’s Hawaii, but now sunken beneath the sea through the forces of waves, rivers, and the slow subsidence of the seafloor,” explained USGS Director Marcia McNutt, in a written statement.

“These data have allowed state and county agencies in Hawaiʻi to account for shoreline change as early as possible in the planning and development process so that coastal communities and public infrastructure can be sited safely away from erosion hazards areas,” said William J. Aila Jr., the chairperson of the Hawaii State Department of Land and Natural Resources.

“This will vastly improve upon public safety and will ensure that Hawaii’s beautiful beaches will be protected from inappropriate shoreline development.”

“Over a century of building along the Hawaiian shoreline, without this sort of detailed knowledge about shoreline change, has led to some development that is located too close to the ocean,” said Dr. Charles Fletcher, a professor  of geology and geophysics at the University of Hawaii, and lead author.

“A better understanding of historical shoreline change and human responses to erosion may improve our ability to avoid erosion hazards in the future.”