How do hills and escarpments affect nearby dune shapes?

Topographic obstructions such as hills and escarpments significantly influence the formation and shape of nearby sand dunes by altering local wind patterns.

When wind encounters a high scarp or a large hill massif, it creates a specific depositional feature known as an echo dune on the upwind side. This dune is separated from the obstruction by a rolling eddy of air, which maintains a sand-free corridor between the dune and the scarp. These echo dunes are among the largest found in desert environments, sometimes reaching heights exceeding 400 metres.1

Additionally, dunes form in sheltered zones on the lee side of small hills as sand migrates into these areas. More broadly, topographical features act to channel winds, which can lead to the development of different dune patterns on various sides of an obstruction.12