National Nonstructural Committee (NNC)

Nonstructural Flood Risk Management

Nonstructural flood risk management measures are proven methods and techniques for reducing flood risk and flood damages by adapting to the natural characteristics of flooding within the floodplain. In addition to being very effective for both short and long term flood risk and flood damage reduction, nonstructural measures can be very cost effective when compared to other flood risk management techniques.

Risk = f [(Probability of Flooding) x (Consequences)]

Probability of Flooding is the frequency of flooding or how often does flooding occur in a particular location.

Consequences are the potential life loss or damages associated with flooding. Structures (residential, commercial, critical, public, and industrial), land use (agricultural, urban, public), and infrastructure (highways, roads, rail, utilities) are the potentially damageable assets. Reduce the consequences of flooding and risk is reduced. Nonstructural measures are invaluable wherein the goal is to reduce flood damages without modifying the characteristics of the flood event.

Nonstructural flood risk management can be categorized as a set of physical or nonphysical measures utilized for mitigating loss of life as well as existing and future flood damages. The physical measures determined to be most commonly implemented are those which adapt to the natural characteristics of the floodplain without adversely affecting or changing those natural flood characteristics. Because of their adaptive characteristics to flood risk, wherein these measures support the National Flood Insurance Program as administered by FEMA and generally cause no adverse affects to the floodplain, flood stages, velocities, or the environment, these measures can be incorporated into existing or new structures to mitigate for potential future flood damages.

Nonstructural measures are permanent or contingent measures applied to a structure and/or its contents that prevent or provide resistance to damage from flooding.  Nonstructural measures differ from structural measures in that they focus on reducing the consequences of flooding instead of focusing on reducing the probability of flooding.

National Nonstructural Committee Logo

Physical Nonstructural measures include:

  • Elevation
  • Dry floodproofing
  • Wet floodproofing
  • Relocation
  • Acquisition

Non-physical Nonstructural measures include:

  • Flood Warning Systems
  • Flood Insurance
  • Floodplain Mapping
  • Flood Emergency Preparedness Plans
  • Land Use Regulation
  • Zoning
  • Evacuation Plans
  • Risk Communication

The National Nonstructural Committee was founded in 1985 to promote the use of nonstructural methods.

                   National Flood Barrier Testing & Certification Program

Flood Mitigation
Certification Program
 

Nonstructural Measures

The different Nonstructural Measures are described provided below. A detailed discussion on each of these types of Nonstructural Measures can be found among our Publications.

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 Evacuation Plans

Evacuation Plans require detailed hydrologic analyses for determining the rate of rise of floodwaters for various rainfall or snowmelt events. When used in conjunction with flood warning systems, this measure can provide significant loss of life avoidance and flood damage reduction benefits. Evacuation planning should consider vertical evacuation as well as the traditional horizontal evacuation. This measures should only be implemented when there is signification response and action time available for floodplain occupants to evacuate. Rally points as well as evacuation routes should be thoughtfully planned and communicated to the public.

 Flood Emergency Preparation

Flood Emergency Preparedness Plans Local officials are encouraged to develop and maintain a flood emergency preparedness plan (FEPP) that identifies hazards, risks and vulnerabilities, and encourages the development of local mitigation. The FEPP should include the community’s response to flooding, location of evacuation centers, evacuation routes, and flood recovery processes.

 Floodplain Mapping

Floodplain Mapping is a nonphysical nonstructural measure identifies flood risk, whether in the form of a map which portrays flood boundaries, or as an inundation map illustrating the depth of flooding, this measure is a significant tool when addressing flood risk.

 Land Use Regulations

Land Use Regulations are effective tools in reducing flood risk and flood damage. The principles of these tools are based in the National Flood Insurance Program (NFIP) which requires minimum standards of floodplain regulation. 

 Risk Communication

Risk Communication  develops and uses educational tools such as presentations, workshops, hand-outs, and pamphlets to communicated flood risk and flood risk reduction measures to government entities and floodplain occupants in an effort to reduce the consequences associated with flooding.

 Zoning

Zoning is also beneficial in reducing flood risk. A community may determine that certain areas are too hazardous for human habitation and restrict development from occurring. Other areas may be determined to be risk free. This is a long-term investment tool for alleviating flood risk.

 Flood Insurance

Flood Insurance provides insurance to assist in recovery from a flood event

 Dry Flood Proofing

Dry Flood Proofing involves sealing building walls with waterproofing compounds, impermeable sheeting, or other materials to prevent the entry of floodwaters into damageable structures. Dry flood proofing is applicable in areas of shallow, low velocity flooding.

 Elevation 

Elevation involves raising the buildings in place so that the structure sees a reduction in frequency and/or depth of flooding during high-water events. Elevation can be done on fill, foundation walls, piers, piles, posts or columns. Selection of proper elevation method depends on flood characteristics such as flood depth or velocity.

 Relocation

Relocation involves moving the structure to another location away from flood hazards. Relocation is the most dependable method of protection and provides the benefit of use of the evacuated floodplain.

 Wet Flood Proofing

Wet Flood Proofing measures allows floodwater to enter the structure, vulnerable items such as utilities appliances and furnaces are relocated or waterproofed to higher locations. By allowing floodwater to enter the structure hydrostatic forces on the inside and outside of the structure can be equalized reducing the risk of structural damage.

 Flood Warning Systems  

Flood Warning Systems alert inhabitants in flood prone areas of impending high water. Depending on the type of warning system and advance time inhabitants have the opportunity to evacuate damageable property and themselves from the flood prone area.

National Nonstructural Committee (NNC)

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 About the NNC

The NNC functions under the general direction of the US Army Corps of Engineers, Headquarters, Directorate of Contingency Operations and Homeland Security, Office of Homeland Security. The National Nonstructural Committee was founded in 1985 to promote the use of nonstructural methods. The objectives of the NNC are to:

  • Provide leadership in formulation, evaluation, and implementation of nonstructural flood and coastal storm risk measures
  • Support Headquarters in the development and implementation of policies regarding nonstructural measures
  • Serve as an integral part of the Headquarters flood risk management team
  • Promote the use of nonstructural measures in accordance with law and policy
 NNC Members:
  • Chair: Rachel Williams
    • Senior Program Manager, NWD/POD-RIT
  • Executive Secretary: Danielle M. Tommaso, CFM
    • Planner, New York District
  • Andrew (Andy) MacInnes, RTS
    • Water Resource Certified Planner, New Orleans District 
  • Drew Minert
    • Planning Branch Chief, Omaha District
  • Jennifer Roberts
    • Plan Formulator, New Orleans District

Contact the NNC

Rachel Williams
Senior Program Manager
Northwestern and Pacific Ocean Divisions-Regional Integration Team
Headquarters U.S. Army Corps of Engineers

402-995-9424
nnc@usace.army.mil