WSP01635

• File Number: 8200.400
• Description: Colorado River Basin - Briefing Documents-History-Correspondence
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/1961
• Author: CSU Civil Engineerin
• Title: Analysis of Precipitation Data in the Upper Colorado River Basin
• Water Supply Pro - Doc Type: Report/Study

OOQ476

23

Ill. A REVIEW OF MAJOR STORMS WHICH HAVE OCCURRED IN THE UPPER COLORADO RIVER BASIN"

A. OBJECTIVES

While reviewing the actual sequence of pre-
cipitation amounts recorded at each of 18 stations
in Western Colorado during a 46-year sample, it
was noted that on rather rare occasions heavy pre-
cipitation amounts occurred simultaneously at many
stations. A very cursory investigation showed that
the occurrence of only one such storm in any par-
ticular year tended to increase sharply the annual
streamflow as measured at Lee Ferry.

A separate investigation was made to care-
fully review a 46 -year sample in order to find all
major storms. to formulate a definition of such
storms. and to study the influence on streamflow.

B. PROCEDURE

For purposes of this study of major storms
the initial sifting of data was based on the collection
of all cases when one-half or more of the several
stations in each of three major sub-basins were
equal to or above certain low threshold values.

Mter all such storms -had been tabulated, the
next step was to establish higher minimum limits
for the total quantity of precipitation per storm.

Although the original tabulation was made
separating the basin into three sub-basins repre-
senting Main Stem, Gunnison, and San Juan, it was
eventually determined that only general storms

In Water Year -
1914 1920 1912 1942 1952 1948 1927 1929 1915 1916
40- ~ f\ ~ f\
c.!!l
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's.
,~ E
30- U J,...
W 0
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m
we
.c 0
" ,~
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~
20- lfl
,
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l
10- I
I
I
I
I
0- Ocl. Oct. Oct. Dec. Oct. June Sep. Oct. Sep.
Sep. Jan. May Nov. May Oct. Mar.
22-2316-172-4 26-28 14--16 4-<; 19-20 2A 12-14 24--26 29-31 11-14 27-28 5-ll 3-4 24--26
191319141914 1919 1920 1911 1912 1941 1941 1941 1951 1947 1927 1929 1914 1915
Storm Dates -
Fig. 33. Listing of the 15 largest major storms occurring in Western Colorado during the 46 -year
period, 1911-12 - 1956-57. Note that these occurred during only 10 of the 46 water years.
* Major storms as treated in this section should
be distinguished from the storm periods d.is-
cussed in other sections.