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Abstract
A method of using two acoustic Doppler current profilers operating at different frequencies and employed at the same measuring vertical to sample a profile of suspended sediment concentration has been previously applied in the Parana River (Argentina) but has not been validated by direct sediment samples. The present work fills this gap by reporting new field data and comparing them with acoustically inferred sediment concentrations. The agreement between directly measured sediment concentrations and grain sizes with corresponding estimates from an employed backscatter model was found to be good (squared correlation coefficients are 0.9 and 0.8, and mean deviations are 14 and 6%, respectively). The interrelations between flow velocity and suspended sediment concentration at fixed locations and in a moving mode along a river cross-section have been also investigated. Observed events of bed sediment re-suspension were found to be highly correlated with fluctuations of the vertical flow velocity, with a 100–150s quasi-periodicity. The size of re-suspension plumes was increasing from the channel thalweg to the low-submerged bar areas.
Acknowledgements
The authors would like to gratefully acknowledge the help provided by Roberto Viejo Mir and Santiago Cañete during the field measurements.
Funding
This research received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 212492 (CLARIS LPB. A Europe–South America Network for Climate Change Assessment and Impact Studies in La Plata Basin). This study was also conducted within the framework of the project “Analysis of construction processes in the floodplain of a large river: the Rio Paraná in its middle reach” granted by the Universidad Nacional del Litoral (Santa Fe, Argentina).
