Recommendations
NFPPR – ARID REGIONS
(Categorized by Priority)
Explanation/rationale
1. Mapping and regulation in arid regions:
(a) it is essential the mapping and regulation of
(a)The NFIP should revise definitions,
floodplains in arid regions be closely linked.
regulations, and elevation requirements in arid
regions for existing Special Flood Hazard Area
zones: approximate Zone A in shallow sheet
flooding less than 1-foot deep, Zone AH in true
ponding areas, and Zone AO where depth
exceeds 3 feet, redefine or use Zone AE.
(b) The NFIP should also clarify the elevation and
freeboard requirements above natural grade in (b) Is this AR, or all floodplains? LL
approximate Zone A, with no BFE (Refer to
44CFR Parts 59.1, 60.3(b) and (c)).
[FEMA, in conjunction with state and local partners]
2. The NFIP should disallow or discourage, through This should be required, but at a minimum
more clear and strongly worded regulations, encouraged with incentives through CRS, grants etc
development in areas subject to flow path
uncertainty, erosion, and debris flow in arid
regions and other geographies. [FEMA, in
conjunction with state and local partners]
3. The NFIP should require the use of new science
and technology to update hydrologic and
hydraulic methods or models for arid regions
projects for determining the risk of flooding,
erosion, and debris flow hazards in arid regions,
including alluvial fans and post-wildfire
conditions.
Due to unique circumstances prevalent in arid
regions, FEMA should encourage the use of
stochastic numerical models to better simulate
location, extent, and depth of flooding in areas of
flow path uncertainty.
[FEMA, in conjunction with state and local partners
and expert NGOs]
4. The
NFIP
should
develop
floodplain Best management practices will vary as appropriate
management techniques which address wildfire, amongst the arid regions.
flood and erosion cycle hazards experienced in
the arid regions. [FEMA, in conjunction with
state and local partners and expert NGOs]
NFPPR rec and explanation
Page 1 of 3
draft 11-21-14
5. The NFIP should resume the needed arid regions
research that was started with the 1985 DMA
Consulting Engineers report to FEMA and the
1996 National Academy study. A starting point
for resuming this effort may include:
a. Review the effectiveness of present
identification, characterization, and
mapping guidelines in Appendix G.
Identify pros and cons.
b. Collect
alluvial
fan
flooding
mitigation efforts utilized in the arid
regions. Establish post-construction
performance of these features.
Identify pros and cons.
c. Establish specific aspects of both
Appendix
G
guidelines
and
mitigations efforts which need
improvement
and/or
further
research and development.
d. Establish, in light of recent
improvements in modeling software,
clear guidance and policy on the
applicability of different software on
active and inactive alluvial fan
flooding areas, and establish
different classifications if necessary
and appropriate.
e. Establish policy and guidance to
ensure that new technology used to
determine flood hazards is not
improperly
used
to
allow
development in areas where high
risk alluvial fan flooding is possible.
f. Coordinate with the Army Corps of
Engineers to develop guidance on
the appropriate application of two
dimensional software (including the
new 2D HEC-RAS) on alluvial fans
and areas of unpredictable flow
paths.
This would produce
defensible recommendations by an
organization with no conflicting
interests in the determination.
Continued research and development of models
and management approaches are essential in all
flood risk areas, but especially in arid regions,
where the science in newer and evolving.
6. FEMA should establish a low-cost? LOMC
process for NFIP communities and to update
FIRMs after major flood-disaster storm events
cause erosion and new flow paths that change
Such a streamlined, process is even more important
to be promoted considering that in the past FEMA
has allowed delineation techniques to be used for
alluvial fans in arid regions that have failed to
NFPPR rec and explanation
This would be a significant effort, but is essential if
the nation is to manage the increasing risk in arid
regions of the nation due to increased population
and development pressure.
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draft 11-21-14
flood risks vertically and/or horizontally.
NFPPR rec and explanation
recognize flow path uncertainty. This resulted in
unintentionally reducing the extent of predicted
Special Flood Hazard Areas and/or under predicting
volumes and depths of flooding and debris.
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draft 11-21-14