Grand Isle, LA Coastal Erosion Rate
Shoreline change 13.7 miles northeast of Grand Isle, LA
Averaged across every transect USGS ran 13.7 miles northeast of Grand Isle, LA, the shoreline has been moving inland at 15.54 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 155.4 feet over the last decade.
The grain of this number
Grand Isle, LA is the nearest named place, 13.7 miles away, to a ~3.5-mile stretch of coast USGS has surveyed - the reading below covers that whole stretch, not a single property in it. Segment center: 29.33, -89.84. Survey years: 2001, method LRR, from USGS's Gulf of Mexico 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 15.54 ft/yr means over time
Run 13.7 miles northeast of Grand Isle, LA's 15.54 ft/yr rate forward 25 years and it implies about 389 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 19 separate transects produced this segment's rate, with 100% individually reading as erosion, rather than relying on any single survey line. Uncertainty on this specific number: 6.2 ft/yr either side. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 10. Source: USGS Open-File Report 2004-1089. Gulf Park Estates, MS sits at national rank 46 for erosion (5.71 ft/yr), one reference point among the 1211 scored segments, 85 miles from here. 1.6 miles up the coast, Grand Isle, LA shows 8.55 ft/yr of eroding.
One address near Grand Isle: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.