A PFD is defined as a continuous or nearly continuous mound or ridge of sand with relatively steep seaward and landward slopes immediately landward and adjacent to the beach and subject to erosion and overtopping from high tides and waves during major coastal storms. The inland limit of the primary frontal dune occurs at the point where there is a distinct change from a relatively steep slope to a relatively mild slope.
Areas designated as Zone VE, by definition, must at a minimum extend to the inland limit of the PFD. Primary frontal dunes are mapped as Zone VE because of their important role as the first line of defense against flooding. The Zone VE designation ensures that dunes are not subject to manmade alterations in a way that could increase potential flood damage. The Zone VE designation also reflects the potential risk of erosion and undermining of structures that exists for primary frontal dunes.