What is one advantage of using GNSS over traditional soundings for seafloor scanning?

Using GNSS (Global Navigation Satellite System) for seafloor scanning offers the significant advantage of eliminating tidal height adjustments. Traditional methods that rely on soundings, such as using lead lines or echo sounders, must account for variations in tide levels when determining the actual depth of the seafloor. The tidal height can fluctuate significantly depending on various factors, like the time of day and weather conditions, making it necessary to perform calculations or corrections to achieve accurate measurements.

In contrast, GNSS provides precise positional data for the survey vessel and allows for the integration of real-time kinematic positioning or post-processed positional information, which can be referenced directly to a geodetic coordinate system. This GPS-based technology inherently accounts for the vessel's location above the water's surface, streamlining the process and reducing the errors associated with tidal influences. By removing the need for tidal height adjustments, the use of GNSS enhances the overall efficiency and accuracy of hydrographic surveys.