Giles Wiggs Sheffield Centre for International Drylands Research

Giles Wiggs Sheffield Centre for International Drylands Research Aeolian dune processes and dynamics 2004 Joint Assembly Montreal, Canada

Dunes in equilibrium…. Best 1993

Measurements of mean windspeed and sediment transport windspeed sand flux Mc. Kenna-Neumann et al 1997 Wiggs 2001

Measurements of shear velocity shear stress mean shear velocity Lancaster et al 1996 U* Wiggs 2001 turbulence

Measurements of Reynolds turbulent stress Reynolds stress Streamline angle

Calibration of numerical models Parsons et al 2004

Parsons et al 2004

Other modelling approaches Werner 1995 - complex systems Baas 2002 Momiji et al 2000

Other modelling approaches - analytical solutions (Hersen, Sauermann, Herrmann, Andreotti) Schwammle & Herrmann 2003 Hersen 2004

Output sand flux Hersen et al 2004 Dune width

Dunes in dis-equilibrium…. ? Hersen 2004 Parker Gay Jr 1999

Conclusions 1. dune research is in a healthy state! 2. measurements of airflow structure improving BUT requires improved understanding of turbulence / sediment transport relationships 3. calibration of computational models allowing greater understanding of form/flow interactions 4. results of analytical models suggest a requirement for more fieldwork focusing on: § dynamics of sediment transfers at the dune and inter-dune scale § longer time-series measurements of dune evolution