Purpose of Hydrographic Surveying

Hydrography

the measurement and description of the physical features of oceans, seas, coasts, lakes, and rivers, including prediction of how they change over time.

safe and efficient navigation

The primary purpose of hydrography is

1. Measure
2. Reference
3. Process
4. Represent
5. Decide

Survey workflow

Accuracy

closeness of measurements to the true value

Completeness

sufficient coverage and information

Currency

information is up-to-date

Clear metadata

information about how the data was collected and processed

cannot see below the waterline

Hydrographic surveys reveal what mariners

Chart navigable depth

Avoid groundings and select safe routes.

Support port access

Maintain channels and plan dredging based on required clearances.

Locate hazards

Identify wrecks, rocks, shoals, and other obstructions.

Keep information current

Account for changes caused by: *Sedimentation *Storms *Construction *Shoreline change

Coastal infrastructure

Ports, channels, reclamation, dredging, cables, pipelines

Environmental management

Habitat mapping, protected areas, pollution response, monitoring

Disaster risk reduction

Coastal/riverine floods, tsunami, and change analysis

Maritime jurisdiction

Boundary delimitation and marine spatial planning

Blue economy & tourism

Safer access, aquaculture, resource use, recreation

Science & modelling

Ocean circulation, climate, sediment, and hazard studies

Geodesy and positioning

Determines the location and coordinates of survey measurements.

Water levels and physical oceanography

Deals with tides, water levels, currents, and other water conditions.

Acoustic depth measurement

Uses acoustic techniques to determine water depths.

Seabed and sub-bottom interpretation

Determines the character and structure of the seabed and material beneath it.

Cartographic communication

Turns survey data into maps, charts, and other understandable products.

Integration

turns observations into usable evidence.

Nautical chart, least depths, hazards;

Bathymetric surface, cross-sections, volumes;

Terrain-bathymetry model, shoreline change;

Seabed character, habitat and change layers;

Quality-controlled depths and metadata

[Users of Hydrography]

User | Hydrographic Product Mariner / Port authority | ___ Engineer / Contractor | ___ Coastal planner / DRRM office | ___ Environmental manager | ___ Researcher / Modeler | ___

Hydrography

measurement and description of the water environment.

Bathymetry

measurement and representation of underwater depths and the shape of the seabed.

Navigable depth

depth sufficient for safe vessel operation.

Least depth

minimum depth found within a surveyed area or feature.

Hazard

underwater feature or obstruction that may threaten navigation.

Under-keel clearance

vertical distance between the bottom of a vessel and the seabed.

Horizontal datum

reference system used for horizontal positioning.

Vertical datum

reference surface used for measuring elevations or depths.

Seabed

bottom surface of a body of water.

Metadata

information describing the data, including its source, collection, processing, and quality.

Bathymetric surface

representation of the underwater terrain based on depth measurement