Revision History for SIR 2020-5142
Katherine J. Chase, Roy Sando, Daniel W. Armstrong, and Peter McCarthy
Regional Regression Equations Based on Channel-Width Characteristics to Estimate Peak-Flow Frequencies at Ungaged Sites in Montana Using Peak-Flow Frequency Data through Water Year 2011
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Posted online August 19, 2021
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Revised and reposted September 20, 2021, version 1.1
The text version was modified.
In table 2, below the "Upper Yellowstone-Central Mountain hydrologic region" spanner, the second equation was changed so the final superscript value was 1.76 rather than 1.77.
In table 4, below the "West hydrologic region" spanner, the first equation was changed so the final superscript value was 1.69 rather than 1.70.
In table 4, below the "Northwest Foothills hydrologic region" spanner, the second equation was changed so the final superscript value was 1.42 rather than 1.41.
In table 4, below the "Northwest Foothills hydrologic region" spanner, the tenth equation was changed so the final superscript value was 1.16 rather than 1.17.
In table 4, below the "Southwest hydrologic region" spanner, the second equation was changed so the final superscript value was 1.51 rather than 1.56.
In the "Limitations of Regional Regression Equations Based on Channel-Width Data" section, a paragraph was added:
"Finally, the methods presented for weighting combined estimates from different regression equations can yield potentially unreasonable results for sites where estimates from methods are highly correlated (rx,y is greater than about 0.5) or SEP values are different (SEP1/SEP2, SEP2/SEP3, or SEP1/SEP3 are greater than about 1.4 or less than about 0.7). If the method for weighting combined estimates from different regression equations results in a QAEP outside the range of estimates for each individual estimate, using a different combination of regression equations, or only one regression equation, can be considered."