The Combined Effect of Sediment Availability and Wind Regime on the Morphology of Aeolian Sand Dunes

摘要

Aeolian-driven sand dune orientation is a key parameter that determines dune morphology. Although wind regime, surface condition, and sediment availability all control sand dune formation, researchers have mostly put emphasis on the wind regime. However, research shows that the formation of dune orientation cannot be explained solely on wind because different dune types can form under the same wind regime in a given area. In this study, we investigate the combined effects of wind regime and sediment availability on dune orientation based on numerical simulations. The model clarifies the extent to which sediment availability influences dune orientation as well as the physical mechanisms that allow for the coexistence of different dune types. We found that linear dunes and barchans can coexist when the sediment availability is less than 10% with a localized sand source, and where barchans are situated at the extremity or on the same flank of the linear dunes. When the angle between two dominant winds is greater than 90 degrees and sediment availability is greater than 10%, oblique dunes may occur, and they can evolve from asymmetric barchans. This study offers insight into the potential relationship between dune-forming factors related to the wind regime and the available erodible sediment within a dune system, in view of the fact that such a model would be a valuable tool in ascertaining the causes behind complex dune formation processes.