The Bayesian estimation and fitting software, RMC-BestFit, has been collaboratively developed by the U.S. Army Corps of Engineers (USACE) Risk Management Center (RMC) and the Engineer Research and Development Center (ERDC) Coastal and Hydraulics Laboratory (CHL). This innovative tool is designed to expedite flood hazard assessments in the communities of Flood Risk Management, Planning, and Dam and Levee Safety. It employs a Bayesian flood frequency analysis approach that can incorporate diverse hydrologic information sources, such as historical data, paleoflood indicators, regional rainfall-runoff results, and expert elicitation.
Recently, RMC-BestFit has been enhanced to include nonstationary flood frequency analysis (NSFFA) capabilities. This feature enables the variation of distribution parameters over time, allowing users to identify evolving flood risk conditions. A case study will be presented, focusing on NSFFA for a high-hazard dam within the USACE portfolio. An example from the semi-arid western region will be featured, showcasing decreasing flood risk over time, providing an opportunity to reduce flood control storage and increase water supply storage for climate resiliency. The study will demonstrate how to assess nonstationarity influenced by factors like land use and climate change. It will also highlight the selection of appropriate trend models for distribution parameters and the integration of historical, censored data, and Global Climate Model (GCM) projections into Bayesian NSFFA. This case study emphasizes the significant impact of NSFFA on flood risk assessments, influencing potential dam safety modifications and reallocation measures.
