What factors are irrelevant for GNSS surveying that are required for soundings?

In the context of GNSS surveying, tidal height and swell effects do not have a bearing on positioning accuracy, making them irrelevant for the GNSS aspects of a survey. GNSS, or Global Navigation Satellite System, primarily focuses on determining precise locations based on satellite signals, independent of water or environmental conditions affecting water levels or surface movement.

Conversely, when conducting soundings—which involve measuring underwater depths—factors such as tidal height and swell effects are critical. These conditions can significantly impact water levels and the accuracy of depth measurements. Therefore, while tidal height and swell effects are vital for ensuring accurate soundings, they do not influence GNSS surveying accuracy and positioning.

Understanding this distinction helps clarify the specific requirements of different components of hydrographic surveying, where GNSS is concerned with providing position data irrespective of the water dynamics that affect soundings.