ABSTRACT

Guidance for Flood Risk Analysis and Mapping: Coastal Erosion   [open pdf - 2MB]

From the Overview: "Erosion processes and consequences of erosion can either be 'episodic' or 'chronic.' These two descriptors assign a very important temporal component to erosion processes and their results. [...] Current FEMA regulations are limited to risks and losses occurring as the direct result of a storm event. The National Flood Insurance Program does not address long-term chronic erosion, but focuses on episodic, flood-related erosion due to coastal storm events. FEMA does not currently map long-term erosion hazard areas as some local or state agencies do. Flood Insurance Rate Maps (FIRMs) indicate risks from flooding hazards in the form of Base Flood Elevations (BFEs) and flood insurance risk zones. Therefore, flood assessment guidelines only include methods for estimating eroded shore and backshore profiles during storm events; the resulting profiles are then used in overland wave propagation, wave runup, and overtopping computations to determine flood risks associated with these events. [...] To estimate erosion and profile changes for a specific coastal setting, it may be important to consider during which season the potential flooding hazard event will likely occur and the condition of the associated beach profile. Many sandy beaches exhibit significant seasonal changes in their profiles due to seasonal differences in weather and wave climate. Where significant storms occur during the winter it may be appropriate for the Mapping Partner to apply a winter profile."

Report Number:
Guidance Document 40
Publisher:
Date:
2018-02
Series:
Copyright:
Public Domain
Retrieved From:
U.S. Federal Emergency Management Agency: https://www.fema.gov/
Format:
pdf
Media Type:
application/pdf
URL:
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