Open space protection and flood mitigation: A national study

Brody, S. D. and Highfield, W. E., 2013. Land Use Policy

Original research (primary data)
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Open space protection is increasingly being used for flood mitigation at the local level. However, little if any empirical research has been conducted on the effectiveness of this land use policy in terms of reducing actual damage caused by floods. Our study addresses this issue by statistically examining the performance of open space dedicated for flood mitigation purposes across a nationally representative sample of local jurisdictions. We measure the amount of open space protection designated under FEMA’s Community Rating System (CRS) program for 450 local communities, and then test the degree to which this strategy reduces insured flood damages over an eleven-year period from 1999 to 2009. Results indicate that, even when controlling for environmental, socioeconomic, and policy-related variables, open space protection is an important land use planning tool for mitigating the adverse impacts of flood events in the U.S. Our findings provide insights for local planners and decision makers interested in pursuing an avoidance strategy of flood mitigation, where people and structures are essentially removed from the most vulnerable locations.

Case studies

Basic information

  • Case ID: INT-105-1
  • Intervention type: Protection
  • Intervention description:

    Open space protection: prevent building in floodplain zone ... to help maintain natural storage capacity ... setbacks from or buffers around riparian areas make space for natural fluctuations of riverine systems and reduces adverse impacts to structures that would otherwise be placed in harm’s way "One of the 18 mitigation activities covered under the CRS is open space preservation (Activity 420) in recognition that one of the most effective approaches to prevent flood damage is to keep flood-prone areas free of development. Several different methods of preserving floodplain lands as open space (OS) are recognized under this activity. To be considered “open space,” the area must be “free from buildings, filling, or other encroachment to flood flows” (FEMA, 2007; 420-2). This requirement is meant to prevent or minimize development that obstructs floodwaters, exposes insurable buildings to damage, or adversely impacts the function of the floodplain. Additional credit points are given if the parcel has a deed restriction prohibiting development or has been preserved in or restored to its natural state."

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Freshwater flooding  Positive per-unit dollar amount of insured flood damage saved by designating open space for flood mitigation
  • Approach implemented in the field: Yes
  • Specific location:

    nationally representative sample of local jurisdictions (in 450 local communities)

  • Country: United States of America
  • Habitat/Biome type: Ecosystem not specified |
  • Issue specific term: Not applicable


  • Notes on intervention effectivness: effectiveness determined by isolating the influence of protected open spaces on reducing observed flood damage over time.
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Not applicable
  • Compare effectivness?: No
  • Compared to the non-NBS approach: Not applicable
  • Report greenhouse gas mitigation?: No
  • Impacts on GHG: Not applicable
  • Assess outcomes of the intervention on natural ecosystems: No
  • Impacts for the ecosystem: Not reported
  • Ecosystem measures:
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures:
  • Considers economic costs: Yes
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: No
  • Experimental evalution done: Not applicable
  • Non-experimental evalution done: Empirical case study
  • Study is systematic: