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Parsons, D.R.1, J.L. Best1, S.N. Lane1, R Kostaschuk1, O Orfeo3, M Franklin1, R.J. Hardy1, J Fraser4
(1) Univ. of Leeds, Leeds, United Kingdom 
(2) University of Guelph, 
(3) CECOAL, CONNICET, Argentina
(4) Reson Offshore Ltd, 

ABSTRACT: The Morphology and Flow Fields of Three-dimensional Dunes, Rio Paraná, Argentina: Results from Simultaneous Multibeam Echo Sounding and Acoustic Doppler Current Profiling

The morphology, flow and process mechanics of river channel dunes has attracted much interest over many years (e.g. Matthes, 1947; Raudkivi, 1966; Jackson, 1976; Yalin, 1992; Nelson, 1993; Bennett and Best, 1995; Kostaschuk, 2000; Best and Kostaschuk, 2002). However, many of these studies have concentrated on two-dimensional (2D) bed features and their associated flow structures and bed stress distributions. This morphological simplification imposes inherent limitations on our interpretation and understanding of dune form and flow dynamics, as natural dunes are invariably three-dimensional (3D) with an associated fully 3D flow structure. For example, studies over 2D forms neglect the significant effect that lateral flow and secondary circulation may have on the flow structure and dune morphology. 
This paper details a field study of a swath of dunes in the Rio Paraná, Argentina. A large (0.25 km wide, 1.8 km long) area of dunes was surveyed using a Multibeam Echo Sounder (MBES), providing high-resolution 3D detail of the river bed. Simultaneous to the MBES survey, 3D flow information was obtained with an Acoustic Doppler Current Profiler (ADCP). This paper will present details of the methodology and results using this integrated approach that has enabled investigation of the interactions between the 3D morphology and 3D flow structure of large alluvial sand dunes.

 

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.