FS - Fundamentals of Surveying Hydrographic Surveying Flashcards
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What is hydrographic surveying primarily concerned with?
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.
What instrument is primarily used to measure water depth in hydrographic surveying?
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.
What does the term 'sounding' refer to in hydrographic surveying?
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.
What is the standard chart datum for US nautical charts and hydrographic surveys?
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.
What is multibeam sonar used for in hydrographic surveys?
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.
What organization publishes official nautical charts for US coastal waters?
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.