Modelling controls on aeolian dune-field pattern evolution



A second-generation, source-to-sink cellular automaton-based model presented here captures and quantifies many of the factors controlling the evolution of aeolian dune-field patterns by varying only a small number of parameters. The role of sediment supply, sediment availability and transport capacity (together defined as sediment state) in the development and evolution of an aeolian dune-field pattern over long time scales is quantified from model simulations. Seven dune-field patterns can be classified from simulation results varying the sediment supply and transport capacity that control the type and frequency of dune interactions, the sediment availability of the system and, ultimately, the development of dune-field patterns. This model allows predictions to be made about the range of sediment supply and wind strengths required to produce the dune-field patterns seen in the real world. A new clustered dune-field pattern is identified from model results and used to propose an alternative mechanism for the formation of superimposed dunes. Bedforms are hypothesized to cluster together, simultaneously forming two spatial scales of bedforms without first developing a large basal dune with small superimposed dunes. Manipulation of boundary conditions produces evolving dune fields with different spatial configurations of sediment supply. Trends of spacing and crest length increase with decreasing variability as the dune field matures. This simple model is a valuable tool which can be used to elucidate the dominant control of aeolian sediment state on the construction and evolution of aeolian dune-field patterns.