engleski

Comparison of flow velocity vectors collected by using RTK-GPS and bottom-tracking as a reference on a boat mounted ADCP

Previous investigations showed that the application of boat-mounted acoustic Doppler current profilers (ADCP) is limited in rivers with substantial bed-load transport if boat velocities are calculated by the built-in bottom-tracking method. In order to overcome this limitation the speed and location of the boat is collected by an external RTK-GPS unit. Nevertheless, few previous studies showed that the navigation errors may arise during pairing of ADCP and GPS units. This in turn maycontribute substantially to the flow velocity errors in ADCP surveys, since the boat speed is usually of the same order of magnitude as the flow velocity. This paper presents comparison of processed raw velocity data between two methods of ADCP surveys: the first by using RTK-GPS as a reference and the second by using the bottom- tracking as a reference. For measured discharges and flow velocities the tendency of bias is analysed in both survey methods.

ADCP, velocity gauging, RTK GPS, moving-bed, Drava River

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