A method for identifying sources of model uncertainty in rainfall-runoff simulations

A major goal in environmental modeling is identifying and quantifying sources of uncertainty in the modeling process. A forecast ensemble is developed in this study for a rainfall-runoff simulation system. This ensemble includes several quantitative precipitation estimates that serve as inputs to the Vflo (TM) hydrologic model. The rainfall estimates are derived from rain gauges, radar, satellite, and combinations, and their probability distribution is assumed to encompass the true, but unknown, rainfall. Sensitive model parameters in the model are also perturbed within their physical bounds to create a combined input-parameter ensemble. If all major sources of uncertainty are accounted for, then observations of river discharge should fall within simulation bounds. Otherwise, there may be additional errors that lie within the model structure.