Hydrographic Surveying - Mapping The Seabed

This factsheet explains how hydrographic surveying is used to map the seabed and support the production of accurate nautical charts. 

 

It describes how surveyors measure water depth using echo sounders that transmit sound pulses to the seabed and calculate depth from the return signal, while also accounting for factors that influence accuracy such as tides, vessel motion and variations in the speed of sound in seawater. 

 

The factsheet also outlines the different technologies used, including single beam and multi‑beam echo sounders and airborne LiDAR, and highlights the challenges of collecting reliable data in dynamic marine environments to ensure safe navigation.