Application of Probable Maximum Flood Estimates to the Design of Water Resource Development Projects

Designs of most major dams and spillways are based on probable maximum floods (PMF). When properly estimated, PMFs provide the basis for confident sizing of spillway. There are, however, many factors which affect the estimation of a PMF. In analyzing each of these factors, certain assumptions have to be made and subjective judgements exercised. Depending on these assumptions and judgements, resulting PMF estimates may be quite different. This paper provides a brief summary of current practices in PMF estimation and application, and offers some guidelines for such practices. It also includes a comparison and discussion of PMF and risk-based analysis for spillway design.