1Hydrographic Surveying
process of measuring and mapping the physical features of bodies of water, particularly the bathymetry of the seafloor.
2Bathymetry
measurement and representation of underwater depths and the shape of the seafloor.
3Depth Determination
one of the most important operations in hydrographic surveying.
4Bed Profile
shape and elevation of the bottom surface of a body of water.
5Sounding
process of measuring the depth of the bed of a body of water at a particular point, or measuring the depth below the water surface.
6Direct Methods
measure water depth through physical contact with the bed.
7Indirect Methods
determine water depth using acoustic signals and reflected sound waves.
8Direct Method
sounding technique that physically measures water depth using a rod, line, or mechanical device.
9Sounding Rod
graduated rod or pole used to directly measure water depth.
10Sounding Rod
Not advisable in areas with strong currents because maintaining verticality is difficult, resulting in incorrect readings.
11Leadline
thin rope with a plummet attached at its end, used to measure water depth.
12Plummet
weighted object attached to the end of a sounding line to reach the waterbed.
13Lead
most common material used for the plummet
14Leadline
Considered the most primitive tool for depth measurement.
15Leadline
Not suitable for swift-flowing water or areas with strong currents.
16Drag Effect
occurs when water current pushes the sounding line away from the vertical position.
17Drag
Measured line length becomes greater than the true water depth.
18Drag
More noticeable in deep and swift-flowing water.
19Drag
A correction must be applied to obtain the correct depth.
20Sounding Machine
improved version of the leadline method that uses a rotating barrel and flexible wire to measure water depth.
21BB
stores and releases the sounding wire.
22Flexible wire
connects the barrel to the lead weight.
23Lead weight
lowered into the water to reach the bed.
24Winding handle
raises or lowers the wire.
25Indirect Method
sounding technique that determines water depth using acoustic signals instead of physical contact with the waterbed.
26Acoustic Technique
method that uses sound waves to determine underwater depth.
27Transducer
device in SONAR that converts electrical energy from the transmitter into high-frequency sound waves.
28SONAR (Sound Navigation and Ranging)
system that uses sound waves to detect and measure underwater objects and distances.
29Echosounder
instrument that determines water depth by transmitting underwater sound pulses and receiving echoes reflected from the riverbed or seabed.
30Transmitting Unit
emits underwater supersonic pulses.
31Receiving Unit
receives echoes reflected from the riverbed or seabed.
32Single Beam Echosounder
instrument that determines water depth by measuring the time interval between the emitted sound pulse and its returning echo.
33Ping
short sound pulse emitted by the transducer.
34Footprint
small area of the bottom covered or insonified by a single sonar pulse.
35Ensonifying
process of filling an area with sound waves.
36Multi-beam Echosounder
instrument that maps a wide, contiguous area of the seafloor using multiple sound beams.
37Wide Angular Lateral Aperture
transducer feature that allows sound beams to cover a wide area across the vessel's path.
38Swath Width
width of the seabed area covered by the multibeam system in one pass.
39Multi-beam Echosounder
Provides wider and more continuous seabed coverage than a single beam echosounder.
40Multichannel Echosounder
hydrographic echosounder that uses a sweep system to map the seafloor across a swath width.
41Sweep System
system used to obtain bottom coverage across a wider area.