Hydrographic surveying is the measurement and description of marine and maritime environmental features such as shorelines, seabeds and riverbeds, currents, and tides. In addition to manned vessels, it can also be carried out by USVs (unmanned surface vehicles) and UUVs (unmanned underwater vehicles) equipped with acoustic technologies, or by UAVs (unmanned aerial vehicles) carrying specialised LiDAR payloads.
Using drones and other autonomous unmanned vehicles for hydrographic surveying saves time and manpower, and surveyors can easily plot pre-programmed routes and edit them during a mission as required. UAVs can be used at low tide to scan for obstructions, and this data can then be used to inform the paths of USVs and UUVs that complete the surveying works during high tide.
Equipment and Applications for Hydrographic Survey
Applications for hydrographic survey include maritime navigation, dredging, offshore drilling and marine construction.
Sonar and Echo Sounders
Used for acoustic hydrographic surveying, sonar technology measures the reflection of acoustic pulses in order to construct an image of the surveyed area.
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Depth Sensors and Underwater Altimeters
Often paired with temperature sensors, depth sensors and underwater altimeters utilize sonar pulses to measure the depth/distance of the seabed and information relating to the features of the seafloor.
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Profiling Floats
Profiling floats or drifters are preprogrammed underwater units used to autonomously relay information concerning currents, salinity and temperature from different points within a vertical water column.
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Tethered Boats
Unmanned tethered boats are remotely operated autonomous surface vehicles (ASVs) used to monitor and exact information relating to a fixed point at sea / on the water.
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Bathymetric LiDAR
UAV LiDAR scanners are typically used for shallow-water bathymetry (underwater depth) measurements, whereas USVs and UUVs with acoustic equipment can be used for a wider range of surveying applications. Unmanned systems can also be used as a force multiplier in conjunction with manned survey vessels and aircraft.
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