Grand Isle, LA Coastal Erosion Rate
Shoreline change 6.1 miles southwest of Grand Isle, LA
Averaged across every transect USGS ran 6.1 miles southwest of Grand Isle, LA, the shoreline has been moving inland at 8.92 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 89.2 feet over the last decade.
What "Grand Isle" means on this page
Grand Isle, LA is the nearest named place, 6.1 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: 29.17, -90.11. 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 8.92 ft/yr means over time
Run 6.1 miles southwest of Grand Isle, LA's 8.92 ft/yr rate forward 25 years and it implies about 223 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
52 transects feed this segment's number; 100% of them individually measured retreat. Uncertainty on this specific number: 0.93 ft/yr either side. This segment ranks 25 of 1211 measured US coastal segments, ordered from fastest erosion to fastest growth. Source: USGS Open-File Report 2004-1089. For scale: Bolivar Peninsula, TX, 274 miles away, ranks 179 of 1211 nationally for erosion, 1.27 ft/yr, 0.1x this stretch's rate. Grand Isle, LA, 2.1 miles off, is the adjacent measured stretch, reading severe erosion at 6.6 ft/yr.
One address near Grand Isle: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.