FS FS - Fundamentals of Surveying Hydrographic Surveying 1 — Questions and Answers
Question 1: What is hydrographic surveying primarily concerned with?
- Underground water table mapping
- Measurement of water bodies and their underwater features (Correct answer)
- Rainfall and precipitation analysis
- Water quality chemical testing
Correct answer: Measurement of water bodies and their underwater features
Hydrographic surveying involves measuring and mapping bodies of water, including water depths, bottom features, and shoreline positions for navigation and engineering purposes.
Question 2: What instrument is primarily used to measure water depth in hydrographic surveying?
- Total station
- Echo sounder (depth sounder) (Correct answer)
- Theodolite
- Water level gauge
Correct answer: Echo sounder (depth sounder)
An echo sounder measures water depth by transmitting acoustic pulses downward and recording the time for the echo to return from the bottom.
Question 3: What does the term 'sounding' refer to in hydrographic surveying?
- Acoustic noise level measurement
- A depth measurement below the water surface (Correct answer)
- The process of locating submerged objects
- Signal transmission between survey vessels
Correct answer: A depth measurement below the water surface
A sounding is a measurement of water depth at a specific location, referenced to a chart datum and plotted on nautical charts.
Question 4: What is the standard chart datum for US nautical charts and hydrographic surveys?
- NAVD 88
- NGVD 29
- Mean Lower Low Water (MLLW) (Correct answer)
- International Great Datum (IGD)
Correct answer: Mean Lower Low Water (MLLW)
Mean Lower Low Water (MLLW) is the standard chart datum for US nautical charts, representing the average of the lower of the two daily low tides.
Question 5: What is multibeam sonar used for in hydrographic surveys?
- Measuring water current velocity
- Collecting depth profiles across a wide swath simultaneously (Correct answer)
- Locating submerged magnetic objects
- Measuring water temperature and salinity
Correct answer: Collecting depth profiles across a wide swath simultaneously
Multibeam sonar emits many acoustic beams simultaneously to map a wide swath of the seafloor, providing complete bottom coverage in a single pass.
Question 6: What organization publishes official nautical charts for US coastal waters?
- US Army Corps of Engineers
- NOAA Office of Coast Survey (Correct answer)
- US Geological Survey
- Federal Emergency Management Agency
Correct answer: NOAA Office of Coast Survey
NOAA's Office of Coast Survey produces and maintains official nautical charts for US coastal, Great Lakes, and inland waterways.
FS FS - Fundamentals of Surveying Hydrographic Surveying 1
What is hydrographic surveying primarily concerned with?