Abstract Submission: Best practices for hydrologic and hydraulic model set up and parametrization are just that, best practices. These represent consistent reasonable approaches to estimate runoff response from a precipitation event, convert the runoff into a stream flow hydrograph, and relate stream flow to stream stage at a location or area of interest. However, these approaches result in estimates and unless vetted through comparison to observed data, are limited in their predictive capability.
Calibration leverages observed precipitation, streamflow, and stream stage. Comparisons of modeled and measured runoff response to rainfall show where differences occur, and model inputs are re-evaluated and re-estimated. This process results in a reduction of uncertainty in the parameter estimates and an improved runoff response.
This presentation provides three examples of hydrologic or hydraulic model calibration. Two of the models, McLoud Run in Cedar Rapids, IA and 5-, 8-, and 10-Mile Creeks in Boise, ID, do not have streamflow measurements within the basins. A lack of relevant measured data made traditional hydrologic calibration or validation methods impractical. In these cases, a paired watershed approach was used to reduce uncertainty in hydrologic modeling parameters and flow estimation for an ungagged watershed. The third model Vermilion River in Lafayette, LA is much the opposite, where two stream flow observation locations, three additional stage observations, and hundreds of high-water marks were available. In this case the challenge was in complexity and scale rather than available data.
The throughline of these cases was a calibration that focused on re-evaluation of the parameter estimation approach to identify processes that were misrepresented in the preliminary model. In each study, refinements made to the parameter estimation procedure and datasets improved the physical representation of runoff response. The outcome of calibration increased confidence in the parameter estimation approach, model parameters, and resulting flow rates and stream stages.
