The Three-Dimensionality of Alluvial Dunes (NERC Fellowship)

PI: Dr D Parsons

Sponsor: NERC

Value: £1120703.26

Dates: 28.11.2005 to 27.11.2008

Summary

Alluival dunes are very common bedforms in river channels and in estuary and coastal environments. They occur in a wide range of flows and sediment sizes. However, despite significant attention over many years, we do not fully understand their physical dynamics or the processes responsible for their formation. The vast majority of alluvial dune fields are inherently three-dimensional (3D); there are many different scales of bedforms and there is variability in dune height, crestline orientation and direction. Our understanding of dunes is primarily based upon investigations into the dynamics of simplified two-dimensional (2D) forms. This simplification has imposed fundamental limitations on the interpretation and understanding of dune form and flow dynamics, since 2D forms do not account for the complexity in the flow structure associated with three-dimensionality. Thus, our ability both to model and to manage the influence of 3D bedforms in rivers and estuarine environments is severely limited. This proposal seeks to adopt an integrated approach to the study of dune three-dimensionality, using a combination of fieldwork and laboratory studies to guide numerical modelling strategies. Many recent methodological and technical developments have been made in these approaches. These improvements now make this research feasible and this proposal seeks to draw on these enhancements to gain a better understanding of dunes generally, and the influence three-dimensionality in particular.