Kaanapali, HI Coastal Erosion Rate
Is the coast eroding 1.4 miles north of Kaanapali, HI?
Good news, and an honest one: USGS's data can't distinguish this stretch, 1.4 miles north of Kaanapali, HI, from a flat trend. Whatever small movement it measured here is statistical noise, not a reliable direction, so none is claimed.
What this reading actually covers
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 Kaanapali, HI, rather than showing one arbitrary line. Segment center: 20.95, -156.69. 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.
What backs this reading up
This reading comes from 263 individual transects averaged together, 81% of which measured erosion rather than growth. Uncertainty on this specific number: 0.21 ft/yr either side. The unadjusted figure here, -0.18 ft/yr, would place it 528 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. Saco, ME sits at national rank 962 for growth (0.3 ft/yr), one reference point among the 1211 scored segments, 5054 miles from here. Napili-Honokowai, HI, 2 miles off, is the adjacent measured stretch, itself no significant trend.
Not this whole stretch, just Kaanapali itself: the Coastal Change Hazards Portal is USGS's own live version of this data.