sonarechosounding

Sonarechosounding, also referred to as sonar echo sounding, is a hydroacoustic method for measuring ocean depth by emitting an acoustic pulse from a transducer and recording the time until echoes return from the seafloor. It is used to create bathymetric maps and support nautical charting, navigation, seafloor geology, and marine research, and it encompasses both single-beam and multi-beam systems.

The emitted pulse travels through seawater at the speed of sound, which varies with temperature, salinity, and depth. Depth is calculated as D = (v × t) / 2, where v is the sound speed in water and t is the two-way travel time. Depth estimates can be affected by inaccuracies in v, water column stratification, vessel motion, seabed reflectivity, and the depth of the transducer itself.

Modern echosounding uses transducers mounted on ships or platforms, connected to pulse generators and receivers. Single-beam systems provide a line of depth measurements, while multi-beam systems use arrays to insonify broad swaths in a single ping, increasing coverage and resolution. The collected data are combined with GNSS positioning and processed to produce bathymetric surfaces and nautical charts. Sub-bottom profiling may accompany echosounding, using longer pulses to image sediment layers beneath the seabed.

Historically, practical echosounders were developed in the 20th century and became standard tools for hydrographic surveying. Today, sonarechosounding remains foundational in marine science and industry, supporting navigation safety, dredging, offshore engineering, and habitat mapping. Limitations include variability in sound speed, water-column noise, platform motion, and seabed characteristics.