Why is sediment supply important for coastal dune growth?

Sediment supply is the fundamental limiting factor in the development and growth of coastal dunes. Because dunes form when wind transports sand from the beach and deposits it behind obstructions, the availability of this sediment dictates the ultimate size and extent of the dune system.1

When sediment is consistently supplied and not removed by erosion, small initial accumulations—such as coppice mounds—can evolve into foredunes. This process allows a coast to prograde, or grow seaward, often resulting in the formation of parallel dune ridges. Conversely, in areas where sediment supply is insufficient, coastal dunes remain small or fail to develop significantly, regardless of wind conditions.12