Probable Flood Hazards Assessment

RTI provides comprehensive Probable Flood Hazard Analyses (PFHA) to support dam safety risk assessments and water infrastructure planning. RTI engineers combine modern hydrologic modeling, statistical analysis, and stochastic simulation to develop probabilistic flood loading relationships that describe the likelihood of extreme inflows, volumes, and reservoir stages.

These analyses form the hydrologic foundation for Semi-Quantitative and Quantitative Risk Assessments (SQRA and QRA) and support defensible, risk-informed decision making for dam safety programs. 

RTI's Tools for Modeling Flood Frequency and Reservoir Loading

• RTI’s nFlow tool allows engineers rapidly to estimate inflow frequency relationships from precipitation-frequency data. The resulting inflow statistics can be integrated with reservoir and system operations using RMC-Reservoir Frequency Analysis (RFA) to generate stage-frequency and outflow-frequency relationships that describe the probability of reservoir loading conditions.
• For watersheds with complex hydrologic behavior or limited observational records, RTI also applies its Stochastic Event Flood Model (SEFM) to simulate thousands of physically plausible flood events that capture variability in precipitation, temperature, snowpack, and antecedent watershed conditions. 

These tools and methods allow RTI engineers develop transparent, technically defensible flood hazard curves that quantify the probability of extreme hydrologic loading conditions across a full range of events—from frequent floods to extremely rare scenarios.

These results provide critical inputs for evaluating dam safety risks, understanding flood-driven failure modes, and prioritizing risk-reduction investments across dam portfolios.