Conference program and abstracts - Coastal-Change.Org

Coastal wind climate, coastal dunes and ventifacts:
mismatch or misinterpretation?
Jasper Knight 1 , Helene Burningham 2
1
School of Geography, Archaeology and Environmental Studies, University
of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa
(jasper.knight@wits.ac.za)
2
Department of Geography, UCL, Pearson Building, Gower Street, London,
WC1E 6BT, UK (h.burningham@ucl.ac.uk)
ABSTRACT
The Atlantic-facing coast of western Ireland experiences a high-energy
onshore wind climate controlled by seasonal patterns of cyclones and
variations in North Atlantic Oscillation index (Burningham and French,
2013). Due to late Pleistocene glacial erosion the coast is also sand-rich,
with well-developed coastal dune systems, sandy beaches with wide
intertidal zones, and sand-filled estuaries. The combination of strong
onshore winds, high sediment availability and sea-level readjustment
throughout the Holocene has led to the formation of extensive coastal
sand dunes (Carter, 1990) andventifacts (Knight and Burningham, 2001;
Knight, 2005). One problem in reconciling these diverse environmental
variables, however, is the mismatch in spatial and temporal scales of
observations. Geomorphological evidence for wind activity records the
net effect of winds over long (10 2 -10 4 yr) time scales, whereas wind records
themselves only span shorter time scales (10 -1 -10 2 yr) but are of higher
resolution. In addition, radiocarbon-dated buried soils within sand dunes
and macroscale sand dune morphologyare difficult to interpret within the
context of periods of enhanced storminess, sediment fluxes between
beach and dunes, and dune deposition and non-deposition (stability).
Likewise, the millennial-scale record of human occupation of these dunes
does not explain the subtle interconnections between dune surface
disturbance, human activity, climate, and ecosystem changes (Knight
and Burningham, 2011). In order to better examine therelationship
between wind climate and its implications foraeolian sediment transport
and the formation, development and maintenance of coastal dunes and
ventifacts, we use high-resolution coastal wind records over a 2-day
period from a site in County Donegal, NW Ireland, where coastal dunes
and ventifacts are actively forming at the present time. The results have
implications for the relationships between climate forcing (as defined by
standard measures of wind climate) and landforms such as coastal sand
dunes and ventifacts that are often linked uncritically to short time-scale
wind datasets. This is likely a significant source of mismatching and/or
misunderstanding in the climatic interpretation of such coastal landforms.
The Fourth IGCP 588: PREPARING FOR COASTAL CHANGE 17