A consideration of the dune: antidune transition in fine gravel
Carling, P.A. and Shvidchenko, A.B. (2002) A consideration of the dune: antidune transition in fine gravel. Sedimentology, 49, (6), 1269-1282. (doi:10.1046/j.1365-3091.2002.00496.x).
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Hydraulic data defining the dune:antidune transition in fine gravel are compared with potential flow theory, and information is drawn from published experiments and field-based studies. Attention is given to both transitional bedforms and the development of downstream-migrating antidunes. In the latter case, most data pertain to sand beds and not to gravel. Empirical data provide some weak support for the theoretical notion that the transition occurs at progressively lower Froude numbers at greater relative depths. Although a critical Froude number of 0·84 may reasonably be applied for the beginning of the dune to antidune transformation, lag effects (and a possible depth limitation) ensure that transitional bedforms may persist across a broad range of Froude numbers from 0·5 to 1·8. This latter observation has great relevance for palaeohydraulic estimates derived from outcrop data. Whereas the application of theoretical bedform existence fields, based upon potential flow theory, to fine gravel was previously purely speculative, the addition of experimental and field data to these plots provides a degree of confidence in applying stability theory to practical geological problems. For the first time, laboratory data pertaining to downstream-migrating gravel antidunes are compared with theory. These bedforms have been reported from certain experimental near-critical flows above sand or gravel beds, but have been observed infrequently in natural streams. However, there are no detailed studies from natural rivers and only a few contentious identifications from outcrops. Nevertheless, the limited hydraulic data conform to theoretical expectations.
|Additional Information:||Unlike sand beds, the transition dunes:antidunes in fine gravels is poorly understood. This paper considered relevant field and flume data and analyses the data in a sound theoretical framework to demonstrate that existing theory agrees well with empirical observations. One of the top down-loaded papers in the journal in 2002.|
|Keywords:||Antidunes, dunes, gravel, palaeohydraulics, supercritical flow.|
|Subjects:||G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
G Geography. Anthropology. Recreation > GB Physical geography
|Divisions:||University Structure - Pre August 2011 > School of Geography > Environmental Processes and Change
|Date Deposited:||09 Mar 2005|
|Last Modified:||27 Mar 2014 18:05|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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