Greenbackville, VA Coastal Erosion Rate
Is the coast eroding 6.3 miles east of Greenbackville, VA?
Averaged across every transect USGS ran 6.3 miles east of Greenbackville, VA, the shoreline has been moving inland at 0.45 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 4.5 feet over the last decade.
The grain of this number
Greenbackville, VA is the nearest named place, 6.3 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: 38.02, -75.27. Survey years: 2007-2009, method LRR, from USGS's New England / Mid-Atlantic 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 0.45 ft/yr means over time
Run 6.3 miles east of Greenbackville, VA's 0.45 ft/yr rate forward 25 years and it implies about 11 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
What backs this reading up
32 transects feed this segment's number; 100% of them individually measured retreat. Uncertainty on this specific number: 0.33 ft/yr either side. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 322. Source: USGS Open-File Report 2010-1119. For scale: Corpus Christi, TX, 1462 miles away, ranks 272 of 1211 nationally for erosion, 0.59 ft/yr, 1.3x this stretch's rate. 2 miles away, Chincoteague, VA is the nearest other measured stretch: accretion (beach growing) at 1.04 ft/yr.
Greenbackville, VA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.