Grand Isle, LA Coastal Erosion Rate
Is the coast eroding 5.3 miles northeast of Grand Isle, LA?
5.3 miles northeast of Grand Isle, LA, the coast is advancing, not retreating, at a measured 4.73 feet a year, sediment accumulating faster than any erosion USGS recorded here. At that rate, the shoreline has gained roughly 47.3 feet over the last decade.
What this reading actually covers
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 Grand Isle, LA. Centered near 29.27°N, 89.97°W. 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.
25 years at this rate
Holding the 4.73 ft/yr accretion rate 5.3 miles northeast of Grand Isle, LA for 25 years would add roughly 118 feet of shoreline, again assuming nothing about the local sediment supply changes.
How solid is this number
Averaging 18 separate transects produced this segment's rate, with 0% individually reading as erosion, rather than relying on any single survey line. The published margin on this reading runs ±1.25 ft/yr. Among the 1211 US coastal segments with a measurable trend, this one ranks 1197 for erosion, 1 being the fastest-retreating coast in the dataset. Source: USGS Open-File Report 2004-1089. For scale: Quinby, VA, 997 miles away, ranks 1184 of 1211 nationally for growth, 3.29 ft/yr, 0.7x this stretch's rate. Grand Isle, LA, 1.6 miles off, is the adjacent measured stretch, itself no significant trend.
Grand Isle, LA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.