Our Landblog has more on the story:

Seventy percent of beaches on the islands of Oahu, Kauai and Maui are undergoing long-term erosion, according to a recent study by the UH School of Ocean and Earth Science Technology and US Geological Survey. 

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

Kaanapali, Maui:

Makapuu, Oahu: