CoastErosionCheck

Kekaha, HI Coastal Erosion Rate

What USGS measures 5.3 miles northwest of Kekaha, HI

No significant trend

Good news, and an honest one: USGS's data can't distinguish this stretch, 5.3 miles northwest of Kekaha, 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 Kekaha, HI, rather than showing one arbitrary line. Segment center: 22.01, -159.78. USGS's Hawaii assessment last surveyed this stretch through 2007-2010, computing the rate with its WLR method. Other US regions were surveyed in different years, sometimes decades apart, so this page states its own rather than implying one national vintage.

How solid is this number

92 transects feed this segment's number; 71% of them individually measured retreat. Uncertainty on this specific number: 0.56 ft/yr either side. The unadjusted figure here, -0.08 ft/yr, would place it 674 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 1153 nationally for growth belongs to Orick, CA, 2464 miles from this stretch, measured at 1.86 ft/yr. Kekaha, HI, 2.3 miles off, is the adjacent measured stretch, itself no significant trend.

Not this whole stretch, just Kekaha itself: the Coastal Change Hazards Portal is USGS's own live version of this data.