Dune Hazard Zones (DHZ)
occur within segments of shoreline backed by a sandy beach and
dune. They refer to the area landward of a reference feature, such as
the existing line of vegetation, that is subject to coastal hazards.
Along dune-backed shorelines the extent of short-term shoreline change
attributable to episodic wave attack events is the primary factor
affecting shoreline stability and thus determines the landward extent
of the zone. Long-term trends of shoreline change attributable to
factors such as the sediment budget or relative sea level rise may
also need to be accounted for in this setting. The hazard assessment
formula for this setting is defined as:
where:
A typical analysis will involve assigning a range of actual values to the individual terms in the formula. By in effect "bracketing the truth", the dune hazard assessment formula provides a rational basis for assessing the relative risk to life and property posed by coastal hazards.
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