Coastal engineering applications of high-resolution lidar bathymetry

In 1994, the US Army Corps of Engineers completed development of the Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) system, a state-of-the-art hydrographic survey instrument. Using lidar (Light Detection And Ranging) technology and operating from a Bell 212 helicopter, SHOALS remotely collects accurate, high-resolution bathymetry at a rate of 8 km 2/h. A nominal depth-and-position measurement spacing of 4 m yields high-density bottom coverage of coastal projects, producing soundings from the above-water beach, or coastal structure, to depths of 40 m. Since becoming fully operational, SHOALS surveyed over 2000 km 2 along the Atlantic Ocean, Pacific Ocean, Gulf of Mexico, Great Lakes, and Caribbean Sea. Survey projects varied from tidal inlets and navigation channels to beach nourishment and monitoring. These projects quantify current coastal structure condition, navigation channel alignments, and morphologic changes over time. In addition to monitoring coastal projects, sediment transport can be estimated with accurate, high-resolution bathymetry. Bathymetry can be translated into sediment transport through a combination of the sediment continuity equation, a surf zone energetics-based longshore transport formula, and bathymetric data. This paper presents the SHOALS system describing both lidar technology and the survey system. Several SHOALS data sets are presented to show today's benefits of high-resolution lidar bathymetry to the coastal engineering community. Finally, ongoing research using these unique data sets is presented to show the future benefits of lidar bathymetry to the coastal field.