Evolution equations for dunes and drumlins

Dunes and drumlins are examples of bedforms, geomorphological patterns in which the surface of the Earth is shaped by the erosive power of wind, water or ice. Aeolian dunes (i.e., desert dunes) are the most familiar such feature. Coastal sand dunes are a feature of common experience, and we are also familiar with the existence of dunes in deserts. Dunes are formed by the erosive power of the wind, which transports the sand particles at the surface, and sculpts them into a variety of shapes. These can be very large (hundreds of metres in elevation), and take a variety of geometric forms depending on the prevailing wind speed and direction(s) (Tsoar 2001). A spectacular example is shown in figure 1.