USA: Integrated flood plain management (#86)
Description
Flood damage is caused by excessive precipitation and is exacerbated by actions that place people and property in watercourses. It accounts for more losses than any other natural hazard in the United States. Providing protection against flood damage involves land use controls and must, therefore, be integrated with other water management objectives. Moreover, floods cross jurisdictions and therefore require co-ordination. Analysing floods requires knowledge of hydrology, engineering, and the social sciences. Responses to floods include measures to regulate land use in the flood plain, use of flood control reservoirs and mitigation techniques, and the preservation of the natural and cultural resources of floodplains. Although Nature tends not to use structural approaches, and there are beneficial effects of floods, reliable flood control structures can prevent devastating damage and loss of life. In the US, flood management has shifted from a structural to a more IWRM approach:
- In the early 1940s, attitudes began to change, influenced by the work of Gilbert White at the University of Chicago.
- In 1966, a national unified programme for flood losses was recommended.
- In 1976, a federal report cited co-ordination as the weakest component of management efforts.
- By 1986, the Federal Emergency Management Agency (FEMA) had assumed responsibility for a federal interagency task force, and presented a mitigation strategy.
- In 1993, after the Great Mississippi River Floods, a report by an interagency review committee stated that structural measures should only be used when they can be integrated into a systems approach to basin-wide flood damage reduction.
- In 2001, an integrated strategy was favoured which involved the participation of three levels of government and the private sector. Most flood plain management is carried out by local government. Both small and large problems are dealt with, and land use and water quality objectives, as well as flood damage reduction, are considered. FEMA operates a comprehensive programme and is developing software (HAZUS) to estimate losses caused by floods on a national basis.
Lessons learned
- Flood damage reduction requires a complex mixture of policies that includes both structural and non-structural measures.
- Structural measures should normally be used only when they can be integrated into a systems approach to basin-wide flood damage reduction.
- Flood policy is closely connected to land use policy and is administered best at the local level.
- In addition to economic effects, flood policy has significant social and environmental implications, and both negative and beneficial effects of floods should be evaluated.
- Effective flood policy requires a comprehensive support programme consisting of flood plain mapping, hydrologic and engineering studies, insurance, warning systems, and related measures for mitigation, response, and recovery.
- River mechanics, sedimentation, changing channels and flood regimes must be considered in the evaluation of flood policy on specific rivers.
Importance of case for IWRM
The case shows how flood plain management requires integration of hydrology, engineering, and social science issues to successfully regulate land use in the flood plain, use flood control reservoirs effectively, apply appropriate mitigation techniques, and to preserve the natural and cultural resources of flood plains.
Contact
Meg Findley
mfindley@genv.org, USAID Environment Information Clearinghouse