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Policy Statement 421 - Floodplain Management

ASCE Policy Statement                                                                                                           421





Approved by the Energy, Environment, and Water Policy Committee on March 22, 2012
Approved by the Public Policy Committee on May 4, 2012
Adopted by the Board of Direction on July 12, 2012



The American Society of Civil Engineers (ASCE) urges governments at all levels to adopt proactive floodplain management policies that:

  • Hold paramount the public’s safety, health, and welfare.
  • Protect and restore, where practical, natural floodplains.
  • Enact land use policies, ordinances and building codes that consider life safety and prevent the development or major redevelopment of communities in unprotected areas below sea level or in high-risk, flood-prone areas.
  • Inform residents in floodplains of the hazards associated with the development or major redevelopment of communities below sea level or in high-risk, flood-prone areas.
  • Develop flood disaster mitigation and relief plans commensurate with remaining risk.
  • Develop and exercise flood disaster preparedness and evacuation plans commensurate with remaining risk.
  • Support creative partnering between federal, state and local governments to adopt floodplain management policies.
  • Fund the design and implementation of floodplain management policies and flood mitigation projects in a timely manner.
  • Incorporate the concept of building disaster resistant communities consistent with sustainable development.
  • Encourage risk appropriate, multiple-uses of flood prone areas.
  • Pursue flood mitigation facilities, including river restoration, wetland restoration, aquifer recharge, improvements in habitat, ecosystems, and water quality, recreation and open space use.
  • Incorporate floodplains into comprehensive watershed management programs.



Development and associated infrastructure in flood prone areas has increased rapidly as people are attracted to historically fertile floodplains and coastal areas.  Even though the benefits of preserving the natural floodplains as flood storage areas and wildlife habitat have been recognized, the floodplains continue to be developed and new inhabitants are subjected to periodic flooding and related devastation, as shown by Hurricanes Katrina and Rita.  People living and working in flood prone areas often have developed a false sense of security. Once a flood occurs, residents and businesses often expect government to reduce or eliminate the risk of flooding through large capital projects.  These populations need the protection of an efficient floodplain management program implemented before the flood occurs.  By recognizing the likelihood of future flooding and the beneficial aspects of the natural floodplain, areas can be protected and communities can become disaster resistant.  

Floodplain management includes the operation of an overall program of corrective and preventive measures for reducing flood damage, including, but not limited to, emergency preparedness plans, flood control works, and floodplain management regulations.  Methods for evaluating the benefits and costs of mixed systems allow for the consideration of both tangible and intangible benefits and costs and should permit formulating programs, including both structural and nonstructural elements, which provide the greatest return on society's investment.



Civil engineers are largely responsible for the implementation of floodplain management programs and the design and maintenance of flood mitigation systems.  Civil engineers recognize the benefits of both floodplain management and flood mitigation and develop projects to educate the public about the importance of first, preserving the natural floodplain, and second, integrating floodplain regulations and flood mitigation projects into comprehensive floodplain management programs. 


ASCE Policy Statement 421 
First Approved in 1994