Approved by the Energy, Environment, and Water Policy Committee on December 20, 2023
Approved by the Public Policy and Practice Committee on May 1, 2024
Adopted by the Board of Direction on July 18, 2024

Policy

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

  • Hold paramount the public’s safety, health, and welfare.
  • Develop high quality flood and coastal storm risk management mapping that considers temporal and spatial variability in rainfall rates and extends information well beyond the 100-year event to support:
  • Land use regulation and flood informed development.
  • Target investments in flood mitigation practices.
  • Protection of natural flood plain functions.
  • Provide access to flood plain information to the public and developers.
  • Encourage continued development of a risk-based flood insurance program that is fair, equitable and utilizes sound engineering and scientific data in establishment of flood insurance rates.
  • Support ongoing grant and funding programs that encourage climate resilience, equity, and sustainability through partnerships at all levels of government.
  • Continue to reauthorize, fund, and enhance the National Flood Insurance Program, including:
  • Adoption of new rules to address the use of 2D and 3D hydraulic modeling software updates.
  • Adoption of new techniques for development of hydrology and mapping of flooding associated with non-riverine and coastal areas.
  • Adoption in law of EO 13690 Federal Flood risk Management Standard.

Issue

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, land use policies, buy-out of flood prone structures, and flood risk reduction systems. Truly effective floodplain management is not limited to the traditional 100-year FEMA floodplain definition, but considers the whole range of possible flood scenarios, including more extreme events and considers temporal and spatial variability in rainfall rates. Floodplain management should consider monetary, environmental, and social benefits and costs.

There are many benefits to society for floodplain management, these include public safety, improved economies, improved habitats, and recreational opportunities.

It has been repeatedly demonstrated that the cost of well-planned mitigation efforts is far less than the expense of repairing damaged property. According to the National Institute of Building Sciences “Natural Hazard Mitigation Saves: 2019 Report” released in December 2019, every dollar spent on mitigation translates into an average savings of $6 for the American public.

Rationale

Throughout the U.S., significant populations and property are currently at significant risk from flooding. These include areas of older development that occurred prior to the adoption of the National Flood Insurance Program and newly developed areas that may be subject to extreme flooding driven by climate change. Effective floodplain management works to both mitigate the existing risk and to prevent or minimize the creation of future risk by considering climate dynamics and utilizing resiliency principles in the design of mitigation projects and establishment of floodplain areas. This requires a balanced approach to:

  • AVOID future risk through land use controls, including prohibitions and protection levels, that keep people out of and infrastructure from being built in harm’s way.
  • REDUCE existing risk through structural projects such as channel improvements, levees, detention and other flood control structures or projects.
  • MITIGATE individual property risk through programs such as elevation of existing structures, relocation and demolition, and rebuilding of non-compliant structures to meet resilient standards.
  • RESTORE natural floodplains and riparian zones primarily through buyouts and restoration activities.

It is the responsibility of civil engineers to provide appropriate planning to reduce risk in to protect public safety and property and to educate the public on existing and future risks.

ASCE Policy Statement 421
First Approved in 1994