The Organisation of Barchan Dune Systems Across Scales

From a process-based perspective, dune environments are governed primarily by wind regime, sediment availability, and vegetation cover. Among aeolian landforms, the distinctive crescent-shaped barchan is arguably the simplest, requiring limited sediment supply, near-unidirectional winds, and an absence of vegetation. Given this apparent simplicity, together with more than 140 years of geomorphological research and their prominent place in Bagnold's classic work, one might expect our understanding of these bedforms to be largely complete. Yet over the past two decades, intensive research combining remote sensing, field observations, laboratory experiments, numerical simulations, and analytical modelling has revealed unexpected complexity. In particular, interactions between dunes can generate emergent behaviours and patterns that cannot be predicted solely from environmental controls such as wind, sediment supply, and vegetation.
In this seminar, I will present my research on barchan dunes within the context of these recent advances. The work spans multiple spatial scales, from the dynamics of individual dunes and pairwise dune interactions, to the collective properties of large dune swarms and the global distribution of barchan systems. Together, these studies illustrate how processes operating at the scale of individual dunes can give rise to large-scale patterns, offering new insights into the organisation and evolution of dune landscapes.