The Hydrologic Engineering Center (HEC) developed the Flood Impact Analysis (HEC-FIA) software to analyze the consequences from a flood event. The software calculates structure and content damages, agricultural losses, and estimates potential life loss. These computations are performed by evaluating deterministically input single events where the HEC-FIA computation uses uncertainty to describe the damageable elements and their susceptibility to flooding.

The results from these computations support U.S. Army Corps of Engineers (USACE) planning studies by supporting other social effects (OSE) account estimates associated with event-based loss of life, property, content and agricultural damage estimates in the user-defined study area. The HEC-FIA software supports dam and levee safety programs by allowing users to evaluate the consequences associated with poor performance (e.g., levee or dam failure) and to perform scalable analyses in support of screening decisions. The software allows for the rapid evaluation of actual events, supporting real-time water management decision-making during the operation of a system of flood risk management infrastructure.

This User's Manual details Version 3.3 of HEC-FIA. Version 3.3 is an update to Version 3.2 of HEC-FIA. HEC-FIA is the successor to the Project Benefit Accomplishment (HEC-PBA) software. HEC-FIA includes the damage-analysis capabilities summarized above and discussed in detail below. The software features the ability to analyze geo-referenced gridded data, utilizes HEC-DSS (HEC's Data Storage System) datasets, produces plots and tabular reports, and interfaces with geographic information systems (GIS). HEC-FIA also includes a graphical user interface (GUI) that allows the user to enter and edit data necessary for flood impact analysis.

In addition to the capabilities listed above, the HEC-FIA software Version 3.3 provides new computation features and methods, specifically improving the flood damages reduced calculations. In the HEC-FIA framework, the components of the watershed configuration were expanded to include HEC-ResSim reservoirs and common computation points with holdout distribution areas. The watershed configuration was enhanced with the addition of an improved method for computing reduced flood damages. The flood damages reduced method uses structures for the damage computation rather than aggregated stage damage functions, which is an improvement over the previous method. In addition a new inundation configuration was created to more flexibility in the computation of flood damages reduced. This new compute is intended for use in watersheds with large leveed areas, or leveed areas with complex hydraulics where the current without levee damage estimations in HEC-FIA are not appropriate. Instead of accepting only 2 hydraulic inputs, regulated and unregulated, this configuration accepts 2 additional hydraulic inputs for the regulated without levee and the unregulated without conditions. This allows a user to compute the without levee hydraulics in HEC-RAS, instead of relying on the without levee estimation in HEC-FIA. Finally, the addition of a reconstruction simulation capability extended the HEC-FIA software to enable the user to compute and analyze estimated damages for a subsequent event following reconstruction from a preceding flood event.