Dauphin Island, AL Coastal Erosion Rate
Shoreline change 1.3 miles east of Dauphin Island, AL
USGS's shoreline-change data puts this stretch, 1.3 miles east of Dauphin Island, AL, at 2.38 feet of erosion a year on average, a long-term rate for this specific ~3.5-mile section, not one storm's damage. At that rate, the shoreline has lost roughly 23.8 feet over the last decade.
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 Dauphin Island, AL, rather than showing one arbitrary line. Segment center: 30.26, -88.15. The survey behind it runs to 2001, in USGS's Gulf of Mexico assessment, using the LRR 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 2.38 ft/yr means over time
Run 1.3 miles east of Dauphin Island, AL's 2.38 ft/yr rate forward 25 years and it implies about 60 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
How solid is this number
Averaging 89 separate transects produced this segment's rate, with 100% individually reading as erosion, rather than relying on any single survey line. The published margin on this reading runs ±1.1 ft/yr. Among the 1211 US coastal segments with a measurable trend, this one ranks 112 for erosion, 1 being the fastest-retreating coast in the dataset. Source: USGS Open-File Report 2004-1089. North Scituate, MA sits at national rank 430 for erosion (0.26 ft/yr), one reference point among the 1211 scored segments, 1269 miles from here. Dauphin Island, AL, 3 miles off, is the adjacent measured stretch, reading moderate erosion at 2.67 ft/yr.
Dauphin Island, AL on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.