Probable Maximum Flood Analysis

RTI provides advanced hydrologic modeling and Probable Maximum Flood (PMF) analyses to support dam safety evaluations, flood hazard assessments, and water resources planning. RTI engineers develop, calibrate, and apply watershed models to estimate the magnitude, timing, and volume of extreme runoff events and evaluate how watersheds respond to severe precipitation conditions. 

RTI's Tools for Flood Hazard and Frequency Analysis

Using industry-standard tools such as HEC-HMS, HEC-ResSim and HEC-RAS, RTI builds physically based models that represent watershed processes including precipitation losses, runoff generation, snowmelt, and channel routing.

These models are calibrated and validated using historical rainfall-runoff events to ensure they accurately represent observed watershed behavior. Once established, the models are used to evaluate a range of extreme hydrologic scenarios, including the Probable Maximum Flood (PMF). 

PMF Results for Dam Safety and Infrastructure Planning

PMF analyses performed by RTI engineers combine Probable Maximum Precipitation (PMP) estimates with calibrated watershed models to simulate the most severe flood conditions that could reasonably occur in a basin. RTI evaluates storm characteristics such as spatial distribution, storm orientation, temporal patterns, and antecedent watershed conditions to identify the most critical precipitation events that drive extreme inflows. Sensitivity analyses are often performed to understand how model parameters, antecedent moisture conditions, reservoir operations, and storm patterns influence PMF results.

The resulting PMF hydrographs provide critical inputs for dam safety evaluations, spillway capacity assessments, and flood routing studies. RTI’s approach emphasizes transparent methods, defensible assumptions, and thorough documentation to ensure analyses meet current federal and state dam safety guidance and can withstand rigorous technical review.