Publication Series and Series Number: Scientific Investigations Report 2005-5029
Title: Verification of 1921 Peak Discharge at
Publication Authorship: M. C. Mastin and D. L. Kresch
First Version and Date of First Release: 1.0 March 8, 2005
Current Version and Date of Current Release: 2.0 August 2005
Summary of Product Components
Last Revised in Pub Version
Date of Last Revision
of 1921 peak discharge at
August 9, 2005
Historical List of Revisions (latest revision first)
Version 2.0—August 2005
Cover 1—Addition of “Version 2.0, August 2005” under report series and number.
Title page—Addition of “Version 2.0, August 2005” under report series and number.
On page 1—Second paragraph, first sentence rewritten as “The four largest annual peak discharges used in the determination of the 100-year flood discharge at Skagit River near Concrete occurred in 1897, 1909, 1917, and 1921.“
On page 1—First paragraph under INTRODUCTION:
Third sentence rewritten as “The 100-year flood, the primary design flood used for these projects is based on the historical peak discharges at Skagit River near Concrete, Wash….inadequate protection measures.”
New 4th sentence added: “Station
12194000 is used to determine the design flood because it has a long period of
record, has a stable stage-discharge rating curve, and is downstream of all
major tributaries in the
Second paragraph under INTRODUCTION, second sentence, “Pursuant…, recently has completed a draft…”, was rewritten as, “Pursuant…, recently completed a draft…”
Third sentence, “A critical…probability the—100-year flood.” was rewritten as “A critical…probability—the 100-year flood.”
Fourth sentence, “Annual peak discharges…1917, and 1921.” was replaced with “A log-Pearson Type III flood-frequency analysis of all available unregulated annual peak discharges at Skagit River near Concrete was used to determine the 100-year flood discharge.
A new paragraph was added following the fourth sentence:
On page 2—Second paragraph, last sentence rewritten as “Therefore, any inaccuracy in the peak discharge of the 1921 flood would affect accuracies of the peak discharges of the other three largest floods used in the flood-frequency analysis.”
Third paragraph, first
sentence rewritten as “The slope-area measurement of the 1921 peak discharge
was based on (1) three surveyed cross sections, along a reach of the river a
short distance downstream of the
On page 14—Figure 10, upper right end of solid line on graph:
1921 “o” changed to “+”; 1898 date changed to 1897; “+” and 1917 date added below 1921 date.
On page 15—Second paragraph, first sentence rewritten as “The relative influence of various estimates of the peak discharge of the December 13, 1921, flood on the determination of the 100-year flood discharge for Skagit River near Concrete gaging station was evaluated by comparing the 100-year flood discharges determined from those estimates.
Remainder of second paragraph, “Annual peak discharges…streamflow data were not available.” was deleted.
Third paragraph, second sentence was rewritten as, “Peak discharges determined in this analysis for the 1921 flood ranged from 10.8 percent greater than…by Stewart.”
Third paragraph, third sentence was rewritten as, “Assuming that the same approximate range in percentage of differences would apply to the other three historic peak discharges, discharges 10 percent greater than and 10 percent less than those determined by Stewart were calculated (table 1).
Fourth paragraph, first sentence: The word “distribution” was replaced with “flood-frequency analysis.”
On page 16—Second paragraph, first sentence was rewritten as, “The four largest annual peak discharges used in the determination of the 100-year flood discharge at Skagit River near Concrete, Washington, occurred in 1897, 1909, 1917, and 1921.
Cover 4—Addition of “Version 2.0, August 2005” under report series and number.
Removed the U.S. Geological Survey 125th anniversary logo