Engineering Guidelines for the Evaluation of Hydropower Projects: Chapter 8- Determination of the Probable Maximum Flood
From ASDSO Dam Safety Toolbox
Federal Energy Regulatory Commission, 2001
There is little chance that hydrology will ever become the precise science that designers, owners, and regulators would like to see. So many parameters define the basin characteristics and hydraulics of runoff that the hydrologic engineer will always need to rely on experience and good judgment. This chapter is intended to provide systematic procedures that will consistently produce a reasonable PMF hydrograph and appropriate reservoir flood levels for evaluation of project safety.
While keeping the inherent uncertainty of hydrologic calculations in mind, the objectives of this chapter of the Guidelines are:
- To recommend a preferred method for developing PMF hydrographs.
- To present procedures which, if implemented by two or more qualified and experienced hydrologic engineers, would result in reasonably close or consistent estimates of the PMF.
- To make recommendations regarding the assumptions that must normally be made in developing a PMF hydrograph for gaged and ungaged sites.
- To produce an approach that will minimize the total effort and cost of required studies, while ensuring that the developed hydrograph is reasonable and pertinent for use in the design or safety analysis of civil works.
- To provide guidelines for choosing appropriate hydrologic and hydraulic parameters.
- To provide greater consistency nationally for procedures used in PMF development, while recognizing the wide variety of hydrologic conditions present across the United States.
Revision ID: 5863
Revision Date: 12/16/2022