In a bathymetric survey, what are the two lengths that need to be determined to arrive at Z (depth)?

In a bathymetric survey, to determine the depth (Z), it is essential to know two lengths: Delta h and D. Delta h refers to the difference in height between the water surface and the seafloor, while D signifies the distance between the survey vessel or sonar system and the point being measured on the seabed. This combination allows for calculating the depth accurately, as the depth is essentially the vertical measurement from the water's surface to the seafloor.

Understanding why these lengths are critical is crucial in hydrographic surveying. By measuring the distance from the water surface to the seafloor (using Delta h) alongside the horizontal distance (D), surveyors can derive the overall depth accurately. This is fundamental for various applications, including safe navigation, underwater construction, and environmental studies.

Other options do not directly relate to the core components of bathymetric depth calculation. Surface level and horizontal distance can be relevant but are not the primary lengths needed in this context. Wave length and frequency are more associated with wave dynamics rather than direct measurements for determining depth. Temperature and pressure can influence sound speed but are not measurements used to calculate depth directly. Thus, Delta h and D are the specific measurements needed in a bathymetric survey to arrive