Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 85
Narellan Creek Catchment
Flood Study
Table 20
FPCC
Flood Planning Constraint Categories (AIDR, 2017)
SubConstraint
Implications
Category
Consideration
Flow conveyance Development or changes to topography The majority of developments and uses have
within flow conveyance areas and flood adverse impacts on flood behaviour. Consider
and storage
areas in the DFE storages areas affect flood behaviour, limiting uses and development to those
A
which will alter flow depth or velocity in compatible with maintaining flood function.
other areas of the floodplain. Changes
can negatively affect the existing
community and other property.
1
H6 hazard in the Hazardous conditions considered unsafe The majority of developments and uses are
for vehicles and people. All building
vulnerable to failure in this flood hazard
DFE
B
A
types are considered vulnerable to
structural failure.
category. Consider limiting developments and
uses to those that are compatible with flood
hazard H6.
Consider compatibility of developments and
Flow conveyance Flow conveyance areas may develop
users with rare flood flows in this area.
area in events during an event larger than the DFE.
larger than the People and buildings in these areas may
be affected by flowing and dangerous
DFE
floodwaters.
H5 hazard in the Hazardous conditions are considered
unsafe for vehicles and people, and all
DFE
buildings are vulnerable to structural
damage.
B
Many uses and developments will be vulnerable
to flood hazard. Consider limiting new uses to
those compatible with flood hazard H5. Consider
treatments such as filling (where this will not
affect flood behaviour) to reduce the hazard to a
level that allows standard development
conditions to be applied. Alternatively, consider
a requirement for special development
conditions.
Area becomes isolated by floodwater or Consequences of isolation and inundation can
Isolated and
be severe. Consider the consequences of:
submerged areas impassable terrain, with loss of
(low flood island evacuation route to the community
• evacuation difficulty or inundation of the area
on the development and its users, which may
in 1%AEP event) evacuation location. The area will
become fully submerged with no flood- include limitations on land use, or on land use
free land in an extreme event, with
that has occupants who are more vulnerable to
ramifications for those who have not
disruption and loss
evacuated and are unable to be rescued. • the development on emergency management
planning for the existing community, including
the need for additional treatments
• the development on community flood
recovery
• disruption or loss of the development on the
users and wider community
C
2
Isolated but not Area becomes isolated by floodwater or Some developments and their users may be
vulnerable to disruption or loss. Consider:
submerged areas impassable terrain, with loss of an
(high flood island evacuation route to a community
• the consequences of disruption or loss of the
in 1%AEP event) evacuation location. The area has some development on the users and the wider
land elevated above the extreme flood community
level. Those not evacuated may be
• limiting land use, or land use that has
isolated with limited or no services, and occupants who are more vulnerable to
will need rescue or resupply until floods disruption and loss
recede and roads are passable.
• additional emergency management treatment
requirements
• issues associated with the level of support
required during a flood, particularly for longduration flood events
D
E
H6 hazard in
events rarer
than the DFE
Hazardous conditions may develop in an Consider the need for additional development
event rarer than the DFE, which may
conditions to reduce the effect of flooding on
have implications for the development the development and its occupants.
and its occupants.
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