Morphodynamics of barchan and dome dunes under variable wind regimes
Résumé
Dome dunes are traditionally interpreted as a transient or an independent class of bed-forms because of their rounded and smooth shape without slipfaces. Here we show that they can also reach a steady state and form dome dune fields, which entail the same interactions between flow, bed topography, and moving sediment as other dune types in the absence of grain-size segregation and vegetation. We study the transition from barchan to dome dunes by increasing the standard deviation of a normal distribution of sand flux orientation in a numerical model. We find that, under steady-state conditions, barchan and dome dunes exhibit the same relationships between their height and migration rate. As shown in Earth's deserts, dome dune shape and migration rate can then be used to estimate sand flux properties, including the variability in transport directionality.