HEC-HMS Tutorials and Guides HMS Modeling Applications Probable Maximum Flood Tutorials Current: Estimating the Probable Maximum Flood (PMF) Starting with No Existing Model PDF Download PDF Download page Estimating the Probable Maximum Flood (PMF) Starting with No Existing Model. Current page Include child pages All pages Estimating the Probable Maximum Flood (PMF) Starting with No Existing Model Introduction to Estimating the PMF with No Existing Model Data Compilation Compute a Synthetic Unit Hydrograph for Several Historical Events Apply a Peaking Factor to the Unit Hydrograph Standardize Unit Hydrographs to a 1-Hour Duration Using the S-Graph Method ×