Screenshot from the e-learning tool that shows a shoreline on Hilton Head Island, SC. This shoreline was tidally referenced using VDatum.
NOAA's Coastal Services Center and National Geodetic Survey recently teamed up to develop online training ("e-learning") for NOAA's VDatum tool, which translates elevation data between 36 different vertical reference systems. With NOAA's e-learning modules, coastal managers can learn to create datum-based shorelines using VDatum.
Coastal managers often need to monitor changes in the shoreline caused by accretion, erosion, and other natural and manmade events. Accurate shoreline data is important because the shoreline is commonly referenced as a boundary component in legal descriptions, as the point of origin for jurisdictional boundaries, and as the boundary between public and private ownership.
Geographers have wrestled with the challenge of mapping the U.S. shoreline since President Thomas Jefferson ordered the Survey of the Coast (NOAA's ancestral agency) in the spring of 1807. Since shorelines are visually interpreted in the field or from imagery, the process of shoreline extraction, as geographers call it, is time-consuming and subject to human interpretation.
As technology has changed, new approaches to shoreline extraction have emerged. Today, lidar is an efficient instrument in the mapmaker’s "toolkit." Lidar, which stands for "light detection and ranging," is a method of detecting distant objects and determining their position by analysis of pulsed laser light reflected from their surfaces.
One of the main benefits of using lidar to develop shoreline data is the ability to derive a datum-based shoreline, that is, one that is tied to a single, specific tidal elevation, such as mean high water. VDatum makes it possible to extract a lidar-based shoreline using a geographic information system (GIS), a computer system used to create maps and compile geographic data.