Pacific Business News/MSNBC - A new study by the U.S. Geological Survey that used aerial photographs to measure shorelines from 1910 to 2007 has found that 70 percent of Hawai'i's beaches are experiencing long-term erosion.
Scientists from the USGS and the UH School of Ocean and Earth Science and Technology studied more than 150 miles of island coastline 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.
The study found erosion on 85 percent of Maui beaches, 71 percent of beaches on Kaua'i and 60 percent of beaches on O'ahu.
The study found erosion on 85 percent of Maui beaches, including Ka‘anapali Beach, seen above.
The researchers found that, although Hawai'i beaches are dominated by erosion as a whole, coastal change is highly variable along the shore--with "cells" of erosion and accretion typically separated by hundreds of feet on continuous beaches or by rocky headlands that divide the coast into many small embayments.
Human interference in natural processes appears to have impacted the measured rates of change. For example, more than 13 miles of beaches in the study were completely lost to erosion--nearly all previously in front of seawalls.
"The results of this research provide critical coastal change information that can be used to inform a wide variety of coastal management decisions," said Dr. Rob Thieler, sponsor of the USGS study.
It will also help in the development of new policies on establishing building setbacks based on the erosion information for specific properties.