Sand Dunes

The purpose of this page is to define sand dunes, a commonly used term in floodplain management.

Definition/Description

Naturally occurring accumulations of sand in ridges or mounds landward of the beach. Human alteration of sand dunes within V Zones is prohibited unless it can be demonstrated that such alteration will not increase potential flood damage.

Sand dunes are important first lines of defense against coastal storms and can do much to reduce losses to inland coastal development. It can be assumed that any removal or other alteration of a sand dune will render the dune more susceptible to erosion and increase potential damages to structures behind that dune.

Communities are advised to prohibit all alterations of sand dunes unless the applicant can submit engineering analyses that demonstrate that flood damages will not be increased prior to issuing any permits.

NFIP Requirement

• 59.1 - Definition
• 60.3 (e)(7) - Alteration of Sand Dunes and Mangrove Stands

Guidance

• IS-9 Managing Floodplain Development Through The National Flood Insurance Program (NFIP) (page 5-47)
• Coastal Construction Manual (FEMA 55) (Section 6.4.3.3)

Related Keywords

• Coastal High Hazard Area

Special Topic Resources

• Dune Walkover Guidance 
  • Coastal Construction Manual (FEMA 55) Appendix I

Supplemental Information for Sand Dunes

The following activates are presumed to render the dune more susceptible to erosion:

1. Any earth-moving activity. The practice of temporarily moving a sand dune, then replacing it after construction, should not be permitted.
2. The removal or cutting of any vegetation should not be allowed.
3. Installing bulkheads or placing riprap should not be allowed.