Nield, Joanna M.
Surface moisture-induced feedback in aeolian environments
Geology, 39, (10), . (doi:10.1130/G32151.1).
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Aeolian dune development is influenced by feedback between surface properties and sediment transport, yet little is known about the larger scale temporal and spatial natures of this relationship. Surface moisture is particularly influential, and is generally recognized in aeolian environments for its ability to increase the critical shear velocity required to entrain sediment in beach settings or, alternatively, to sustain vegetation and stabilize surfaces at a dune-field scale. However, conceptual models and field work have alluded to its importance in protodune initiation, while field observations infer that seasonal moisture input may contribute to residual dune ridge formation at the dune-field scale. This has the potential to reveal geomorphic adaptation to variations in climate, and identify a recognizable signature in the rock record. This article presents a simulation model that produces geomorphological features similar to field observations and is capable of examining the implications of surface and transport feedback at both scales. Results (1) reveal the control of surface moisture at different temporal scales, (2) display complexity in the development of multiple spatial scales within a cellular automaton framework, (3) highlight the importance of transient sand strips and sediment supply frequency in aeolian transport dynamics and protodune development, and (4) explore the relationship and significance of feedback duration, development time, and bedform spatial scale in the development of incipient dunes. This study illustrates the importance of considering geomorphic feedback when assessing the influence of surface moisture in aeolian process–dominated systems.
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