Abstract:
The Hydrologic Engineering Center's Flood Damage Analysis (HEC-FDA) computer program is designed to assist Corps of Engineers study team members in using risk analysis methods for flood damage reduction studies as required by the Corps (EM 1110-2-1419). The approach explicitly incorporates descriptions of uncertainty of key parameters and functions into project benefit and performance analyses.
... The following is a description of how HEC-FDA is used in flood-damage-reductions studies during plan development.
The typical Corps of Engineers study evolves through five phases:
1. Reconnaissance study phase
2. Feasibility study phase;
3. Preconstruction engineering and design phase;
4. Construction phase; and
5. Operation and maintenance phase.
HEC-FDA is designed to assist study team members during the feasibility study phase of a flood damage reduction study. The objective of a feasibility study is to investigate and recommend solutions to water resources problems. The effort during the early stage of the feasibility study consists of evaluation of plan alternatives, including the without-project condition, and verifying the amount and level of detail of the studies and field investigations to be accomplished. Sufficient engineering and design are performed to enable refinement of the project features, prepare the baseline cost estimate, develop a design and construction schedule, and to allow detailed design on the selected plan to begin at the start of the next phase. The objective is to allow the project to proceed through the preconstruction engineering and design phase without the need for major changes.
The feasibility study must demonstrate that the proposed project contributes to national economic development (NED). That is, the project benefits must exceed the costs. Benefits from plans for reducing flood hazards accrue primarily through the reduction in actual or potential damage associated with land use. These benefits may be classified as inundation-reduction benefits, intensification benefits, or location benefits, depending on the response to flood damage reduction. 
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