Woods Hole Group obtained observations of tidal currents in the St. Lucie Inlet and adjacent waterways using a vessel-mounted Acoustic Doppler Current Profiler (ADCP) coupled with a GPS-based integrated navigation (IN) system.  The surveys were designed to obtain high-resolution measurements of tidal current velocities, as well as to map temporal variations in the spatial structure of flow through the Inlet and waterway cross sections.  Each section was traversed repeatedly through a complete lunar semi-diurnal tidal cycle (12.4 hours), with a transect (repetition) time step ranging from 0.5 to 1.5 hours.  The ADCP provided continuous current profiles with a vertical resolution of 20 cm (5 independent vertical measurements per meter of water depth) and a horizontal resolution of approximately 5 meters (dependent upon vessel speed and averaging interval).  Results of the surveys show current energy focused in specific areas of each cross section, typically where the channel was deepest. Countercurrents were observed along the Inlet margins at specific stages of the tide.  Freshwater/salt water stratification features were also identified.

The geometry of the waterway (i.e. channel bends, points, jetties, shoals) as well as the prevailing alongshore coastal currents appeared to modify the spatial structure of the tidal currents, creating for example transient tidal eddies in the vicinity of channel constrictions. The results from these surveys were used to calibrate a numerical model of Inlet hydrodynamics, to quantify the effect of Inlet geometry on the spatial structure of tidal flow, and assist in explaining sediment accretion/scour characteristics within the Inlet.