Author(s): Robert D. Carl
Linked Author(s): Robert Carl
Keywords: No Keywords
Abstract: The U. S. Army Corps of Engineers is responsible for furthering national economic development by reducing flood risk through both structural and nonstructural measures. When proposing solutions to existing flooding problems, the Corps must evaluate expected annual damage (EAD) for both the “without project” and “with project” conditions. Expected annual damage is computed by integrating a damage-probability function that is derived from three primary functions: 1) discharge-probability 2) stage-discharge and 3) stage-aggregated damage. Figure 1 depicts this as “bat wing” curves. One component of determining the economic viability of a proposed plan is to calculate the inundation benefit which is simply the difference between the EAD for the “without” and “with” plans. The final economic benefit is determined from many other components such as project costs, intensification benefits, and location benefits. Over the last several years (particularly since hurricane Katrina), the terminology and analysis requirements have changed and the focus has moved from “flood damage reduction” to “flood risk management” and has given greater importance to non-economic components such as social consequences/potential loss of life. The Corps has used risk procedures in flood damage analyses for about the last 15 years. Initially, risk analysis was performed with a spreadsheet add-on and was later replaced by a comprehensive computer program called “Hydrologic Engineering Center's Flood Damage Reduction Program” or HEC-FDA (USACE, 2008b). HEC-FDA invokes Monte-Carlo simulation to determine the distribution of EAD and various statistical outputs including those used to “certify” levees under the FEMA requirements. This presentation will describe the current status of HEC-FDA and some of HEC's experiences in applying the techniques to flood risk problems.
Year: 2009