hydrographic

Hydrographic is an adjective relating to hydrography, the science of measuring and describing physical features of oceans, seas, rivers, and lakes and the coastal zones around them. It covers the mapping of underwater topography (bathymetry) and shorelines, as well as the measurement of tides, currents, water levels, salinity, temperature, and other oceanographic properties. The results, usually compiled as nautical charts and related products, support safe navigation, coastal planning, and environmental monitoring.

Hydrographic surveys use specialized equipment and procedures to collect data. Acoustic sounding with single-beam or multibeam echosounders maps depths; side-scan sonar reveals seabed characteristics; tide gauges monitor sea level; Doppler current meters measure currents; and then data are integrated with GNSS positioning. Increasingly, hydrography employs autonomous underwater vehicles, remotely operated vehicles, aerial lidar and photogrammetry, and satellite altimetry. Data processing yields bathymetric charts, digital elevation models of shallow areas, and marine geospatial databases. Standards and interoperability are provided by the International Hydrographic Organization, with specifications such as S-44 for survey integrity, S-57 for digital hydrographic data, and S-100 for modern standards-based products.

History: Early hydrography emerged from navigational lead lines and coastal sounding; it advanced through echo-sounding and later multibeam systems in the 20th century, augmented by satellite-based measurements and numerical modeling. Modern hydrographic offices coordinate mapping and charting for national waters and international shipping lanes.

Applications: Navigation safety, port and harbor development, dredging planning, offshore energy infrastructure, flood and coastal risk assessment, and habitat and resource management. Hydrographic data also support scientific research, climate studies, and maritime law compliance by providing accurate geographic reference frames.