Kapaa, HI Coastal Erosion Rate
Shoreline change 3 miles east of Kapaa, HI
Good news, and an honest one: USGS's data can't distinguish this stretch, 3 miles east of Kapaa, HI, from a flat trend. Whatever small movement it measured here is statistical noise, not a reliable direction, so none is claimed.
The grain of this number
USGS surveys the coast in transects spaced a few hundred feet apart; this page groups the nearest ones into a single ~3.5-mile reading for the stretch closest to Kapaa, HI, rather than showing one arbitrary line. Segment center: 22.10, -159.31. Survey years: 2007-2010, method WLR, from USGS's Hawaii shoreline-change assessment. That's how current the data is here, real, but not a live feed, since a shoreline survey is a major undertaking, not an annual check-in.
How solid is this number
This reading comes from 168 individual transects averaged together, 86% of which measured erosion rather than growth. The published margin on this reading runs ±0.26 ft/yr. The unadjusted figure here, -0.23 ft/yr, would place it 469 of 1211 if ranked directly - but an unreliable rank isn't a useful one, which is exactly why "no significant trend" is the headline instead. Source: USGS Open-File Report 2011-1009. Coronado, CA sits at national rank 1147 for growth (1.69 ft/yr), one reference point among the 1211 scored segments, 2667 miles from here. 2.5 miles up the coast, Wailua, HI shows 0.18 ft/yr of eroding.
Not this whole stretch, just Kapaa itself: the Coastal Change Hazards Portal is USGS's own live version of this data.