The map below shows  QTC  Acoustic Seabed Classification over a digital terrain model of a tunnel crossing of the Fraser River.  Rip-rap over the tunnel  appears  red and green, typical river sediments  appear  blue.    Also see "Sounding Surveys " page.Loading...

Equipment such as Quester Tangent QTC View can classify bottom sediments based on the characteristics of the returned acoustic signal. These units are usually deployed on ships of opportunity and the sounder is located in the hull of the ship.

In areas of significant topographic relief the acoustic footprint (the area of the sea floor insonified by the sounder) can vary considerably. This leads to some variable averaging of the acoustic parameters that are mapped by the system.

CGRC is investigating the use of bottom classification with a towed vehicle.  Underwater video surveys are improved  because bottom images can be correlated with QTC View  parameters. Acoustic mapping is improved because the acoustic footprint is minimized (the towfish travels 0.8m to 2.0 m from the bottom). Bottom classification can also be verified by STING measurements.

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