This document describes the Headquarters, U.S. Army Corps of Engineers' (HQ USACE), purposes, processes, and procedures for production of annual flood damages reduced (AFDR) data for reporting to Congress. This guide document discusses the background and purpose of AFDR, selection of flood events, methodologies for computing AFDR using the Corps Water Management System (CWMS) for various types of watersheds, and procedures for upward reporting.
AFDR reporting to Congress (as Appendix G) is the capstone report that documents annual recurring benefits of federally funded Corps flood reduction projects. The AFDR report and associated data highlight the importance of Corps flood control projects and are used to demonstrate the effectiveness of the nation's water resources investments and rate of returns from those investments. Additionally, the AFDR report can convey the unseen benefits of USACE flood reduction projects by exhibiting the dichotomy between the with and without project inundations for a given storm event. The analyses necessary to produce AFDR data require a high level of expertise in hydrology and hydraulics (H&H) modeling, a high-level understanding of flood consequence economics, and close coordination between the experts in these fields. This guide outlines the methodologies and procedures to compute AFDR using CWMS.