Scope of hydrographic survey: which of the following tasks are relevant components of a hydrographic survey program for charting and coastal engineering?

Introduction / Context:
Hydrographic surveys integrate vertical and horizontal control with bathymetry and shoreline mapping to support safe navigation and coastal engineering. The question asks which item is not relevant; recognizing that all listed tasks are in fact relevant leads to the correct choice.

Given Data / Assumptions:

• Bench marks provide vertical control tied to a chart datum.
• Horizontal control points establish position reference for soundings and shoreline features.
• Sea bed profiling defines bathymetry for charts, dredging, and design.
• Shoreline and hazard depiction (islands, rocks) is essential for navigation safety.

Concept / Approach:
A complete hydrographic program contains all four elements. Therefore, there is no item in the list that is 'not relevant'. The appropriate answer is 'none of these', meaning none of the listed tasks are irrelevant.

Step-by-Step Solution:
Evaluate each option against hydrographic objectives—each aligns with standard practice.Conclude that every listed task is relevant.Select 'none of these' as the statement that correctly indicates there is no irrelevant task listed.

Verification / Alternative check:
Hydrographic standards (e.g., IHO) emphasize control networks, bathymetry, and shoreline/hazard mapping as core components.

Why Other Options Are Wrong:

• Picking any single task as 'not relevant' contradicts accepted practice.

Common Pitfalls:

• Undervaluing control establishment because modern GNSS is available—bench marks and control remain necessary for datum and QA.

Final Answer:
none of these.