Parameter estimation methods for models of major flood events in ungauged mountain basins of Colorado
Date
2021
Authors
Irvin, Ben Christopher, IV, author
Niemann, Jeffrey D., advisor
Schumacher, Russ S., committee member
Bailey, Ryan, committee member
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Abstract
Accurate hydrologic modeling of ungauged mountain basins plays an important role in ensuring the safety of Colorado's dams. Recent research has shown that infiltration-excess runoff, saturation-excess runoff, and subsurface stormflow can all contribute to streamflow from major storms in Colorado's mountains, and the soil moisture accounting (SMA) method in HEC-HMS has been suggested as an appropriate approach to model these mechanisms. However, SMA requires estimation of parameters that have not been previously considered in dam safety analyses. The objectives of this work are to (1) evaluate simplifications to the modeling process that would reduce the number of required parameters and (2) develop methods to estimate the remaining parameters in ungauged mountain basins of Colorado where calibration to observed discharges is not possible. The proposed simplifications and parameter estimation methods are tested for five basins in the Front Range and three basins in the San Juan Range that have streamflow data available for major flood events. For these historical events, the proposed uncalibrated models produce the same streamflow generation processes as calibrated models and the predicted peak discharges from the uncalibrated models usually have 25% errors or smaller. For design storms, the peak discharges from the proposed uncalibrated models can differ substantially from the peak discharges from calibrated models but are conservative relative to the envelope of observed peak discharges.
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Subject
flood
parameter estimation
ungauged basin
mountains
Colorado
soil moisture accounting