Waianae, HI Coastal Erosion Rate
Is the coast eroding 0.9 miles west of Waianae, HI?
Good news, and an honest one: USGS's data can't distinguish this stretch, 0.9 miles west of Waianae, 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 Waianae, HI, rather than showing one arbitrary line. Segment center: 21.45, -158.20. 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
Averaging 116 separate transects produced this segment's rate, with 72% individually reading as erosion, rather than relying on any single survey line. The published margin on this reading runs ±0.28 ft/yr. The unadjusted figure here, -0.17 ft/yr, would place it 541 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. Rank 1108 nationally for growth belongs to Sarita, TX, 3813 miles from this stretch, measured at 1 ft/yr. 2.6 miles away, Makaha, HI is the nearest other measured stretch: also no significant trend.
One address near Waianae: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.