Wailua, HI Coastal Erosion Rate
Is the coast eroding 0.9 miles south of Wailua, HI?
0.9 miles south of Wailua, HI: USGS's transects didn't pick up a trend here that beats the survey's own uncertainty. That's the majority case nationally, and for this stretch specifically it means the coast is holding, not that the data failed to find anything.
The grain of this number
This is a roughly 3.5-mile stretch of coast, not one address or parcel - USGS's own transects run every few hundred feet, but that's finer than any one property needs, so this page reports the stretch nearest Wailua, HI. Centered near 22.04°N, 159.34°W. The survey behind it runs to 2007-2010, in USGS's Hawaii assessment, using the WLR method. Shoreline surveys aren't repeated every year, so this is the most recent long-term measurement USGS has published for this coast, not a live reading.
What backs this reading up
This reading comes from 180 individual transects averaged together, 70% of which measured erosion rather than growth. Uncertainty on this specific number: 0.35 ft/yr either side. Taken at face value, this segment's raw -0.1 ft/yr reading would land it 645 of 1211 nationally - a number worth ignoring, since it's statistical noise rather than a real trend. Source: USGS Open-File Report 2011-1009. For scale: San Clemente, CA, 2656 miles away, ranks 980 of 1211 nationally for growth, 0.34 ft/yr. 1.8 miles away, Wailua, HI is the nearest other measured stretch: slight erosion at 0.18 ft/yr.
One address near Wailua: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.