CST Level 1 Land Surveyor Certification Practice

Hydrographic surveys must be referenced to which datum/s?

1. Horizontal and Tidal

2. Vertical only

3. Horizontal and Vertical

4. Tidal only

The correct answer is: Horizontal and Vertical

Hydrographic surveys are essential for mapping underwater features and understanding the characteristics of bodies of water. These surveys require both horizontal and vertical datums to accurately represent the measurements taken. The horizontal datum provides a geographic reference frame for locating features on the Earth's surface. This ensures that the positions of points surveyed in relation to the shoreline or other land features are accurate. The vertical datum, on the other hand, is crucial for measuring depths and elevations. In hydrographic surveys, measurements of depth depend on a consistent vertical reference to account for tide fluctuations and other water level changes. Tidal datums serve a specific function within hydrographic surveys by providing a reference for varying water levels caused by tides. However, relying solely on tidal datum would not give a complete picture of the horizontal positioning of features surveyed. Therefore, incorporating both horizontal and vertical datums is necessary for a comprehensive understanding and accurate representation of the survey area. Including just one type of datum neglects critical aspects that ensure the overall precision needed in hydrographic studies, thereby reinforcing the importance of both horizontal and vertical references in this context.