Identifying Sources of Uncertainy in Flood Frequency Analysis
Question: How uncertain are flood frequency analyses (FFAs), and what aspects of the modeling chain in FFAs have the most sensitivity?
Hypothesis: We postulate that true FFA uncertainty may be larger than currently appreciated and that different components of the modeling chain such as model choice, parameter values or initial conditions impact FFAs by different amounts. We propose to explore key components of the modeling chain: 1) expanding from one model to a multi-model ensemble, 2) varying model parameters, and 3) varying initial conditions for each model structure. Furthermore, uncertainty and sensitivity characteristics likely vary across hydroclimatic regime. To address this hypothesis, we will use continuous ensemble simulations across model structures with parameter perturbations to drive a stochastic event simulation framework to reveal true FFA uncertainty and understand sensitivities across several case-study basins spanning the hydroloclimatology of the 17 western states.
Need and Benefit
Reclamation infrastructure across the 17 states requires estimates of flood events for risk analysis and design and modification of existing structures (Brekke, 2011). Currently, models are chosen at project onset from a small suite of existing models commonly used within TSC. Those models are then calibrated to existing flow observations through model parameter modification.
The goal of the proposed research is to inform model choice, structure, and parameterization to more efficiently and accurately estimate flood loads for Reclamation infrastructure. Multiple basins covering relevant hydrologic regions will be studied. Currently, there is not a substantial effort at project onset to choose model structure and focused calibration parameters based on hydrologic region. The goal of this study would be to optimize model selection and parameterization for future flood hazard studies.
Contact the Principal Investigator for information about partners.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Identifying Sources of Uncertainty in Flood Frequency Analyses (final, PDF, 2.5MB)
By Amanda Stone, Andrew Newman, Kathleen Homan
Report completed on September 30, 2020