1What is one primary purpose of hydrographic surveying?
To depict the bathymetry of the seafloor\
2What is one of the most important operations in hydrographic surveying?
Depth determination\
3What is the main learning outcome of Lesson 4.1?
Identifying the suitable sounding method or equipment based on the project's purpose and area\
4What is the determination of the bed profile of a water body?
Sounding\
5What is the measurement of the depth of the bed below the water surface?
Sounding\
6What are the two main categories of sounding methods?
Direct methods and indirect methods\
7What are the three direct sounding methods?
Sounding rods or poles, leadline, and sounding machine\
8What are sounding rods generally graduated in?
Meters, decimeters, and half-decimeters\
9In what direction are the graduations of sounding rods arranged?
From the bottom upwards\
10What does the sounding rod reading at the water surface directly indicate?
The depth of water\
11What is fitted at the bottom of a sounding rod to maintain its verticality?
An arrow or lead shoe\
12What is the purpose of the arrow or lead shoe on a sounding rod?
To maintain the rod's verticality during sounding\
13What should be the base area of the arrow or lead shoe?
Large enough to prevent it from sinking into the mud at the bed\
14Where is the use of sounding rods not advisable?
Areas with strong currents\
15Why are sounding rods unsuitable for areas with strong currents?
It is difficult to maintain the rod's verticality, resulting in incorrect measurements\
16What is another name for a sounding line?
Leadline\
17What is a leadline made of?
A thin rope with a plummet attached at its end\
18What is the most common material used for a leadline plummet?
Lead\
19Why is it called a leadline regardless of the plummet's composition?
Because lead is the most common material used for the plummet\
20What is considered the most primitive tool in depth measurement?
Leadline\
21Who manually casts or swings the leadline into the water?
The leadsman\
22At what intervals is a leadline graduated?
Every meter\
23What materials are used for leadline graduation tags?
Cloth or leather\
24Where are leadlines unsuitable for taking soundings?
Areas with swift-flowing water or strong currents\
25Why does a leadline give a greater measured length than the true depth in deep, swift-flowing water?
Because of drag\
26What correction is required when drag affects a leadline measurement?
A correction to the measured length to obtain the correct depth\
27What is a sounding machine?
An improved version of the leadline method\
28What are the main components of a sounding machine?
A rotatable barrel, flexible wire, and lead weight\
29How can the barrel of a sounding machine be rotated?
Automatically or manually\
30What is attached to one end of the flexible wire in a sounding machine?
A lead weight\
31What mechanism raises or lowers the weight of a sounding machine?
The winding handle\
32When is a sounding machine particularly useful?
When taking a large number of soundings\
33Up to what water depth is a sounding machine useful?
30 meters\
34What are the two main categories of sounding methods?
Direct and indirect methods\
35What techniques are commonly used in indirect depth determination?
Acoustic techniques\
36What device is used in acoustic depth determination?
Transducer\
37What does a transducer convert into high-frequency sound?
Electrical energy from the transmitter\
38What does SONAR stand for?
Sound Navigation and Ranging\
39What is the most common equipment used in indirect sounding?
Echosounder\
40What are the two main units of an echosounder?
Transmitting unit and receiving unit\
41What does the transmitter of an echosounder emit?
Underwater supersonic pulses\
42What activates the receiver of an echosounder?
The echoes of reflected pulses from the river or sea bed\
43What are the three types of echosounders discussed in Lesson 4.1?
Single Beam Echosounder (SBES), Multi-beam Echosounder (MBES), and Multichannel Echosounder (MCES)\
44What is another name for a Single Beam Echosounder (SBES)?
Fathometer\
45How does a Single Beam Echosounder determine water depth?
By measuring the time interval between the emitted sound and its returning echo\
46What is the sonar pulse emitted by an SBES commonly called?
Ping\
47Where is the transducer of an SBES positioned?
Just below the water surface\
48What does ensonifying mean?
Filling an area with sound\
49What type of area does an SBES ensonify beneath the boat?
A small area\
50What type of transducer does a Multi-beam Echosounder (MBES) have?
A wide angular lateral aperture transducer\
51What does an MBES map on the seafloor?
A contiguous area of the bottom\
52In what direction does an MBES usually map a strip of points?
Perpendicular to the path of the survey vessel\
53What provides broader coverage in an MBES survey?
Successive pings during one vessel traverse\
54What problem of earlier sounding methods does MBES reduce or eliminate?
Gaps in coverage\
55What is the full name of MCES?
Multichannel Echosounder\
56What type of system does an MCES use to map the seafloor?
A sweep system\
57What type of water bodies is an MCES specifically designed for?
Canals, rivers, and other shallow bodies of water\
58What does an MCES provide through its depth and bottom detection capabilities?
Detailed bottom imagery