Author(s): Joanna C. Curran

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Abstract: The transport of sediment and water define channel geomorphology. In many channels, the majority of the sediment moves as bedload during large floods. Measurements of bedload are difficult and often problematic due to the high stream velocities of which they are often associated. Direct measurements have traditionally been made using HelleyͲSmiths meters or by placing buckets in the bed during low flow stage. Neither method provides a satisfactory sample of bedload across a large channel during floods. The buckets fill before the bedload transport event ends and Helley Smiths are limited in the amount of sediment that can be safely caught and brought to the surface. A nonͲintrusive option for measuring bedload is to use an Acoustic Doppler Current Profiler (ADCP) and to quantify bedload transport rates from the recorded Doppler signal. The current research presents an application of the ADCP to the transport of mixedͲsized sediment in a Central Texas channel. A collected sample of bedload transport is used to calibrate the signature of the ADCP. Then velocity data extracted from ADCP software is compared with physical measurements of the channel bed composition to estimate both total and fractional bedload transport rates. The method provides a faster and safer measurement technique, which could be used to improve the collection and quantity of available bedload data.

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Year: 2009