bathimetri

Bathymetry is the measurement of the depth of water bodies and the mapping of underwater topography. It complements topography on land, and together they describe the seafloor and lakebed. The term derives from Greek bathos, depth, and metron, measure.

Historically, depth was measured with a weighted rope or sounding line, giving single-point depth data. The 20th century brought sonar technology, starting with echo sounding, then computer-assisted bathymetry. Modern surveys use multibeam sonar to cover wide swaths in a single pass, increasing efficiency and accuracy. Data are integrated into bathymetric digital elevation models (DEMs) and bathymetric charts.

Methods include hydrographic surveys from ships, autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs), as well as shallow-water lidar and satellite altimetry to provide complementary data.

Applications include safe navigation, harbor design, submarine cable routing, coastal erosion studies, underwater habitat mapping, sediment transport studies, tsunami and flood modeling, and hydrographic charting.

Data standards and sources: depth is commonly expressed in meters relative to a datum such as mean sea level; vertical reference systems vary by region. Data are managed by national hydrographic offices and international initiatives, and are increasingly shared as open data. Bathymetric information supports oceanography, marine geology, coastal engineering, and environmental planning.