Hydrography

Hydrography is the science of measurement and description of the physical features of bodies of water and their adjacent areas. It encompasses the mapping of seabed topography, shorelines, tides, currents, and water properties, with the goal of producing reliable data for navigation, coastal management, and hydrological research.

Modern hydrography combines field surveys, remote sensing, and data processing. Field methods include echo sounding and multibeam sonar to determine depth, acoustic Doppler current profilers to measure flow, and water sampling for temperature, salinity, and density profiles. Satellite altimetry and airborne LiDAR extend coverage to offshore and shallow zones. Data are processed, quality-controlled, and standardized to international conventions, primarily by the International Hydrographic Organization.

Products and applications include nautical charts, bathymetric maps, tide and current data, and shoreline and seabed models. These data support safe navigation, port development, dredging, offshore engineering, flood risk assessment, and environmental monitoring. Hydrography covers oceans, seas, coastal areas, rivers, and lakes, with national hydrographic offices often responsible for surveys and chart publication. Key standards include S-44 survey quality, S-57 electronic navigational charts, and the newer S-101 framework. Soundings are typically expressed in meters, with chart datums defined to relate depth to a reference surface.