Baddock_Geology-2017-Nield-271-4.pdf (417.51 kB)
Download fileCoupling leeside grainfall to avalanche characteristics in aeolian dune dynamics
journal contribution
posted on 2017-01-06, 10:53 authored by Joanna M. Nield, Giles F.S. Wiggs, Matthew BaddockMatthew Baddock, Martin H.T. HipondokaAvalanche (grainflow) processes are fundamental drivers of dune morphodynamics and
are typically initiated by grainfall accumulations. In sedimentary systems, however, the dynamism
between grainfall and grainflow remains unspecified because simple measurements are
hampered by the inherent instability of lee slopes. Here, for the first time, terrestrial laser
scanning is used to quantify key aspects of the grainfall process on the lee (slip face) of a
barchan sand dune. We determine grainfall zone extent and flux and show their variability
under differing wind speeds. The increase in the downwind distance from the brink of peak
grainfall under stronger winds provides a mechanism that explains the competence of large
avalanches to descend the entire lee slope. These findings highlight important interactions
between wind speed, grainfall, and subsequent grainflow that influence dune migration rates
and are important for correct interpretation of dune stratigraphy.
Funding
This study was funded by National Geographic Society Science and Exploration Europe (GEFNE110-14), British Society for Geomorphology and NERC GEF )1025) grants.
History
Department
- Geography and Environment