Risk Analysis and Uncertainty in Flood Damage Reduction Studies (2000) / Chapter Skim
Currently Skimming:
Executive Summary
Executive Summary
Pages 1-11
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 1... ...
Army Corps of Engineers employs its expertise in hydrology, hydraulics, and geotechnical and structural engineering. Dams, levees, and other river works must be sized to local conditions; geotechnical theories and applications help ensure that structures will safely withstand potential hydraulic and seismic forces; and economic considerations must be balanced to ensure that reductions in flood damages are commensurate with project costs and associated impacts on social, economic, and environmental values.
|
From page 2... ...
These issues came to a head in a Corps flood damage reduction project planning study in Portage, Wisconsin in the early 1990s. The Corps study recommended a levee of elevation 798.3 feet for the city of Portage.
|
From page 3... ...
: The Secretary (Anny) shall enter into an agreement with the National Academy of Sciences to conduct a study of the Corps of Engineers' use of risk-based analysis for the evaluation of hydrology, hydrauTics, and economics in flood damage reduction studies.
|
From page 4... ...
This computer program, the Hydrologic Engineering Center Flood Damage Assessment (HEC-FDA) program, is the principal tool used in Corps district offices to calculate flood damage risks.
|
From page 5... ...
This is a measure of the likelihood that people will be flooded (including the probability of failure of flood damage reduction structures, such as levees) in any given year, considering the full range of floods that can occur and all sources of uncertainty.
|
From page 6... ...
As the current method has shortcomings in these areas, the committee recommends that the Corps improve its analysis of hydrologic, hydraulic, geotechnical, and economic uncertainties. The Corps's conceptual approach of distinguishing between natural variability and knowledge uncertainty is reflected in the engineering modeling components of its risk analysis method, but the conceptual approach needs refinement.
|
From page 7... ...
The committee recommends that the Corps undertake statistical ex post studies to compare predictions of geotechnical levee failure probabilities made by the reliability model against frequencies of actual levee failures during floods. In addition, the committee recommends that the Corps conduct statistical ex post studies with respect to the performance of other flood damage reduction structures (e.g., embankments, detention basins, hydraulic facilities)
|
From page 8... ...
a conditional nonexceedance probability of 95 percent of passing a 1% flood. Although this three-tiered criterion represents a reasonable transition from the former certification criterion into the risk analysis framework, it has the following deficiencies: (1)
|
From page 9... ...
This annual exceedance probability of flooding should include uncertainties derived from both natural variability and knowledge uncertainty. The criterion for certifying a levee should be that it provides satisfactory protection against failure of the flood damage reduction system, expressed as an annual probability of flooding.
|
From page 10... ...
As currently specified by the federal Economic and Environmental Principles and Guidelines for Water and Related Land Resources Implementation Studies, flood damage reduction studies emphasize direct economic damage reductions and the costs of alternatives; these are quantified in the Corps's risk analysis methodology. To ensure that the Corps's flood damage reduction projects provide adequate social and environmental benefits, the committee recommends that the Corps explicitly address potential loss of life, other social consequences, and environmental consequences in its risk analysis.
|
From page 11... ...
The Corps should seek guidance from the Office of Management and Budget and seek consistency with other federal agencies on the use of alternative metrics for incorporating potential loss of life, environmental impacts, and other effects of floods.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.