Uncertainty Analysis: You Need to Know What You Don't Know

Many of the ideas presented in this paper have been around for numerous years. The main proponent of this approach for use in water resources subjects is the U.S. Army Corps of Engineers (COE) and it use is mandated for COE flood control projects. In the early 1990s, the COE and other entities re-examined the concept of freeboard for their flood control projects and felt that the use of Risk and Uncertainty concepts would help quantify the additional required protection above the design elevation instead of adding a somewhat arbitrary value (NRC, 2000). This paper presents the concepts of Risk and Uncertainty Analysis (affectionately termed as RU) as applicable to floodplain management and issues. It also goes over some of the important aspects of RU analysis that should be understood by water resources engineers and floodplain managers. Within about 5 years, floodplain managers will be required to be knowledgeable on the subject of Risk and Uncertainty!