Tidal zoning and vertical reference measuring Cook Inlet, Alaska 1999

Summary form only given. The U.S. Department of Commerce, National Oceanic and Atmospheric Administration National Ocean Service, Office of Coast Survey, Hydrographic Survey Division (NOS) is in the process of obtaining basic nautical charting of 160 square nautical miles (136000 acres) of upper Cook Inlet shipping lanes during the summers of 1999 and 2000. Multibeam surveying techniques will be required meeting the International Hydrographic Organization (IHO) specifications. Racal Pelagos (RPI) and its subcontractors, LCMF Incorporated (LCMF) and Terra Surveys LLC (Terra), conducted an extensive vertical reference measurement and tidal study in upper Cook Inlet during the fall of 1998 and throughout the survey period in the summer of 1999. The primary task was to establish a tidal zoning scheme suitable for supporting the accuracy requirements of multibeam hydrographic surveys. The tidal regime for this area is the most complex in the United States, as the tidal range is large, sites are remote, extensive mud flats are prevalent, high currents are the norm, and the weather is severe. The tide correction can exceed thirty feet and constitutes by far the largest part of the error budget. The project included the installation of multiple tide stations, operating for the duration of the summer field season from early May through September 1999. During the preliminary surveys of 1998, a tidal reduction method was developed and implemented during the multibeam surveys during 1999-2000.