JOINT METOC OFFICER COURSE (JMOC)Types of Hydrographic Surveys
TERMINAL OBJECTIVE:
1.0 EXPLAIN the types of hydrographic surveys as related to hydrographic requirements. 
ENABLING OBJECTIVES:
30 September 2010
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Accurate determination of bathymetry is important both for the purposes of monitoring underwater topography and for producing nautical charts.
Remote sensing bathymetry offers flexible, efficient, and cost-effective means of mapping bathymetry over broad areas.
Introduction
Categories of remote sensing include:
Imaging
Non-imaging
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Remote sensing imaging techniques base the estimation of water depth on the pixel values of an image.
They make use of microwave radiation and visible light.
Imaging Techniques
Captures variations in sea surface roughness to determine bathymetry.
As a result of its vulnerability to wind influences, microwave’s accuracy is rather low.
Microwave
Most frequently used for a wide range of water bodies.
Captures variations in visible light intensity to determine water depth.
Most complex remote sensing bathymetry techniques.
Photo
Provides continuous data recording automatically in near-shore waters.
Best deployed in the intertidal zone to map beach bathymetry and to survey shoreline elevations less than 15 cm.
Video
Non-Imaging Technique
Also known as optical radar or laser radar.
Transmits high-power pulses of laser light at short intervals over an area.
Water depth is measured from the two-way travel time of a pulse.
LIDAR
Remote sensing techniques applicable to bathymetry.
Summary
References