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AIRCRAFT LASER BEACH MAPPING

Overview


Beaches are one of the earth's most dynamic geologic features. Beach morphology fluctuates over a wide range of time scales, varying from periods of hours associated with diurnal tides and storm events, to years and decades associated with long-term erosional trends. Population and development of the coast, especially during the last 100 years, have created a situation in which beach erosion can have severe economic consequences. Estimates reveal that approximately $3 trillion worth of U.S. coastal development is potentially vulnerable to erosion. It is also estimated that 70 percent of the world's beaches are undergoing erosion with percentages approaching 90 percent along the Atlantic coastal plain.

Accurate and timely assessment of erosion conditions and storm impacts is needed to assist decision making on land use, beach renourishment, erosion calculations, insurance compensation, and property value estimation. Proper storm damage assessment is an enormous task for emergency and disaster response agencies and personnel. Federal, state, and local agencies have traditionally used aerial photographs and land surveys to assess the overall impact of storms. Even though these measurement methods provide valuable information, they are often not precise enough to describe specific coastal topographic changes that enable implementation of fully effective shoreline emergency response or development planning along with beach renourishment programs.

Aircraft remote sensing techniques, such as laser beach mapping for coastal topographic measurement, provide the opportunity to gather cost-effective, regional, and high spatial resolution coverage of beach elevations with high vertical and horizontal accuracy. Laser beach mapping also has the potential to provide an accurate baseline survey of all U.S. coastal areas. Annual beach mapping surveys could be repeated to gather an understanding of long-term coastal behavior, and estimate the effects of beach renourishment and artificial beach stabilization structures such as groins, jetties, seawalls, revetments, and breakwaters. With an established baseline survey for a general coastal area, regional surveys could be conducted after the passage of a major storm such as a hurricane to quantify the resulting impacts and allow quick determination of high-risk beach areas. The National Flood Insurance Program (NFIP) and the Federal Emergency Management Agency (FEMA) may find the resulting beach mapping data useful in making decisions on property coverage regulations and insurance adjustments. The NFIP currently provides flood insurance to approximately 1,200 coastal communities, resulting in 1.4 million policies with over $120 billion in flood protection coverage.

In addition, the beach mapping data could be integrated into state coastal programs for local beach management aimed at sustainable economic development with minimal environmental impact. Given the continuing rapid development within coastal areas, these state agencies need access to more precise and rapid sources of beach condition information to adapt their regulations and setback lines to this ever changing environment.

Beach mapping of U.S. coastal areas can be accomplished at a modest cost while providing extensive data to facilitate erosion quantification, damage assessment, and emergency response. This beach mapping data would help to ensure the most strategic allocation of emergency response resources while minimizing additional loss of life and property damage. Beach mapping has strong potential to provide additional resources for state and federal government agencies struggling to deal with day-to-day coastal management.


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