Dauphin Island, AL Coastal Erosion Rate
Shoreline change 1.7 miles west of Dauphin Island, AL
USGS's shoreline-change data puts this stretch, 1.7 miles west of Dauphin Island, AL, at 2.67 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 26.7 feet over the last decade.
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 Dauphin Island, AL, rather than showing one arbitrary line. Segment center: 30.25, -88.20. 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 2.67 ft/yr means over time
Run 1.7 miles west of Dauphin Island, AL's 2.67 ft/yr rate forward 25 years and it implies about 67 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 96 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 ±1.08 ft/yr. This segment ranks 105 of 1211 measured US coastal segments, ordered from fastest erosion to fastest growth. Source: USGS Open-File Report 2004-1089. For scale: Wachapreague, VA, 881 miles away, ranks 68 of 1211 nationally for erosion, 4.24 ft/yr, 1.6x this stretch's rate. 2.3 miles up the coast, Dauphin Island, AL shows 2.07 ft/yr of eroding.
Not this whole stretch, just Dauphin Island itself: the Coastal Change Hazards Portal is USGS's own live version of this data.