Monitoring New Pass, Florida, with High Density Lidar Bathymetry

Abstract

New Pass, Florida provides one of three exchanges between the Gulf of Mexico and Sarasota Bay. Hydrodynamic conditions in the region provide a micro-tidal environment with a diurnal range of approximately 0.6 m, and maximum flood and ebb current speeds at New Pass are on the order of ±6 m/s. The long term average wave height is less than 0.4 m. The area contains an ample supply of sediments with an annual net transport rate on the order of 25,000 m³. New Pass has been maintained as a federal navigation project since the 1960's, requiring periodic dredging to maintain a navigation channel that tends to migrate southward. The beach to the north, on Longboat Key, was nourished in 1993 with sand mined from the pass' ebb tidal shoal. In 1994 a new hydrographic survey system, SHOALS, was field tested in the New Pass vicinity and completed a survey of the pass. Since the first survey, SHOALS has resurveyed the area on two other occasions obtaining unique data consisting of high resolution bathymetry. This paper utilizes the high resolution bathymetry produced by three SHOALS surveys to evaluate the continuing evolution of New Pass as it is influenced by meteorological and astronomical forces and man-made changes.