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Laser maps shoreline change

A laser developed by NASA to map polar ice sheets may become an important new tool in the effort to preserve America's beaches.

Scientists at NOAA's Office for Coastal Management are working to convert data gathered with the NASA-developed technology into viable products that will enable state coastal zone managers to document shoreline movement.

When compared to traditional beach surveys, the new technology will offer a greater number of survey points in a shorter amount of time and at a greatly reduced cost. Annual surveys of this type help scientists and coastal managers understand long-term erosion trends, estimate the effects of beach renourishment and erosion-control devices, and establish set-back lines.

Project scientists use a laser called the Airborne Topographic Mapper, which is flown along the coast in a NOAA aircraft. The laser collects 3,000 to 5,000 spot elevations per second as the aircraft flies over the beach at about 60 meters per second (135 mph). Using the laser, along with global positioning system satellite receivers, researchers survey beach elevations to a vertical accuracy of about 10 centimeters.

In October 1997, researchers surveyed portions of the West Coast prior to the arrival of El Niño, the periodic weather phenomenon blamed for harsh winter weather along the Pacific Coast. Later this year, the same area will be surveyed to document how the beaches and cliffs weathered the storms. East Coast surveys were conducted in October 1996 and 1997.

The program's official title is the Airborne LIDAR Assessment of Coastal Erosion, or "ALACE." The project includes three parts: data collection, data processing, and data validation. Also in development is a web-based data delivery system.

In the end, the Center hopes to develop a set of protocols that will allow states to contract with private firms to undertake their own laser-based beach surveys. The data that is produced will conform to national standards, yet states will be able to dictate the specific areas to be surveyed, when the flights are to occur, and the data format.

Partners for this project include NASA and the U.S. Geological Survey. For additional information about laser beach mapping, call Mark Jansen of the NOAA Office for Coastal Management at 843.740.1262. The web site address is www.coast.noaa.gov/crs/ALACE/.

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