Dunes are almost entirely built by sand's interaction with wind. Sand can be produced or deposited in a variety of ways, whether it is through deposit from the ocean or another body of water or the desertification of an area. Once the sand is deposited, the prevailing winds tend to determine whether a dune will be formed and what shape it will take.
So if a large deposit of sand is formed by deposit or desertification, the most common formation is built by the wind pushing on one side of the deposited sand and creating a taller side and a steeper drop off on the lee side (the side out of the wind). Depending on the influence of the wind, different shapes can be built as well.
sand dunes form when the water pushes the sediment outwards and then the wind carries it farther.the dunes are sculpted by the wind .