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S
Nature-Based Floodplain Management
Exists, and Federal Agencies Should
Know How to Implement It
ASFPM Conference 2017
American Rivers
Jonathon Loos
Eileen Shader
Natural Infrastructure
Already Exists, Lets Use
It
S Nature-based/Natural
infrastructure/Green solutions
utilize natural processes to meet
human needs
S Leverage natural processes,
sometimes with engineered
structures, while avoiding
ecosystem degradation
S Using floodplains to convey floods
Frazer Bend levee setback on the
Missouri River, RM 557
S Reconnected 980 acres of floodplain
S Reduced 1% flow velocity by 34% (4.1 fps 2.7 fps)*
S Reduced 1% flow stage 1.44 ft. *
S Reduced loading on levees*
*These benefits brought to you by your local floodplains
Multiple-Benefit Projects
S Improve safety of a community
S Avoid maintenance and repair costs
S Restore and maintain ecosystem functions
S Provide recreational and education opportunities
S Advance climate mitigation/adaptation objectives
Federal agencies have a firm policy
platform from which to implement
nature-based approaches
I. Implement existing policies that encourage nature-based
approaches
II. Develop guidance for nature-based approaches, looking
toward successes at state and local levels
III. Integrate natural processes into planning and investments
Three areas to work on:
I. Implement existing policies that
encourage nature-based approaches
To begin, consider ecosystem services
S 2015 Executive
Memorandum directing
federal agencies to
consider ecosystem
services in planning,
investments and
regulatory contexts.
I. Implement existing policies that encourage nature-based approaches
Updated Federal Flood Risk
Management Standards (FFRMS)
S Policy: E.O. 13690 set safer standards for federal
investments in the floodplain;
1. 2 ft. freeboard (3 ft. for critical structures) or,
2. 0.2% chance flood level (500 year floodplain) or,
3. Best available climate informed science
S AND instructs agencies to use nature-based approaches
when developing alternatives
I. Implement existing policies that encourage nature-based approaches
U.S. Army Corps. Levee
Management
S WRDA 2016 included two nature-based provisions:
S Sec. 1176 Rehabilitation Assistance – Enables USACE to
fund restoration and nature-based projects in repairing levees
through PL 84-99
S Sec 1184 Consideration of Measures – Requires USACE to
consider nature-based approaches in flood protection measures
I. Implement existing policies that encourage nature-based approaches
FEMA’s Hazard Mitigation Assistance
(HMA)
S Climate Resilient Mitigation Activities became eligible
for HMA in 2015:
S Floodplain and Stream restoration – for flood or drought
mitigation.
I. Implement existing policies that encourage nature-based approaches
II. Develop guidance for nature-based
approaches, looking toward successes
at state and local levels
S Status quo: rebuild levees to pre-event
specifications
S Guidance: Don’t rebuild in place if we don’t
need to, consider multiple-benefits, and even
restoration
S Ex: levee setback to increase conveyance
capacity
ACE: Think outside (or behind) the
levee
II. Develop guidance for nature-based approaches, looking toward successes at state and local levels
ACE: Enable green-gray designs in
flood management projects
S Status Quo: SWIF address levee deficiencies, but
not adverse levee impacts on water quality or
ecological functions
S Guidance: Riparian vegetation allowance, log-
revetments, habitat features
S Ex: Nooksack River, WA SWIF design
II. Develop guidance for nature-based approaches, looking toward successes at state and local levels
FEMA: Revisit hazard mitigation
assistance eligible projects
S Status quo: HMA projects are for
building and planning
S Guidance: Restoring natural
functions can also mitigate floods
S Example: Reestablishing historic
side-channels to reduce risk to
development
II. Develop guidance for nature-based approaches, looking toward successes at state and local levels
III. Integrate natural process into
planning and investments
Watershed-scale planning
S Need: Flood and erosion risks are a product of activity
across the watershed, as is ecosystem health
S Guidance: “Asset management” approach to managing
resources and infrastructure at watershed scale
S Ex: Critical areas ordinances, prioritized restoration areas,
economic and ecosystem resiliency programs
III. Integrate natural process into planning and investments
Integrate riverine erosion or channel
migration zones into NFIP
S Need: FIRMs don’t account for all
geomorphic processes
S Guidance: Technical support to develop
programs adapted to local needs
S Ex: Erosion hazard and channel migration
zones already mapped in VT, WA, NH, IL,
TX
* See ASFPM Riverine Erosion Hazards White Paper
III. Integrate natural process into planning and investments
East Fork Hood River, OR
Reactionary to Designed System
S Our floodplains are managed through three systems-
1. Regulatory standards that guide development, mitigate risk
2. Flood fighting system post-flood event
3. Project design-build efforts
S How do we align incentives and objectives among them?
1. Evaluation of levee setbacks as a sustainable solution along the Missouri River. 2011.
https://acwi.gov/sos/pubs/3rdJFIC/Contents/4E-Krause.pdf
2. Federal Resource Management and Ecosystem Services Guidebook;
https://nespguidebook.com/
3. Nooksack River SWIF vegetation design schematics and management.
http://kulshanservices.com/Documents/SWIF/Veg&hab/VegMgmtPlan/Final_SWIF_VM
P_11-12-14.pdf
