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<br />Table 5.3.--Monthly 1985-level depleted base snowmelt flood for
<br />Glen Canyon Dam
<br />
<br /> 100-year 1985-level 1985-level
<br /> snowmelt flood depletion depleted flow
<br />Month (acre:"'feet) (acre-feet) (acre-feet)
<br />January 691,400 108,400 583,000
<br />February 581,100 72,300 508,800
<br />March 978,200 108,500 869,700
<br />April 1,959,200 253,100 1,706,100
<br />May 7,259,500 397,700 6,861,800
<br />June 6,516,100 578,400 5,937,700
<br />July 3,594,400 723,000 2,871,400
<br />August 1,513,200 650,700 862,500
<br />September 910,800 361,500 549,300
<br />October 456,700 144,600 312,100
<br />November 408,400 108,400 300,000
<br />December 506,000 108,500 397,500
<br />Total 25,375,000 3,615,100 21,759,900
<br />
<br />5.4 DAILY DEPLETIONS FOR GLEN CANYON DAM
<br />
<br />The 100-year base snowmelt flood hydrograph consists of daily
<br />values. Therefore, accompanying 1985-level daily depletions were
<br />needed to determine the daily 100-year depleted base snowmelt flood
<br />for Glen Canyon. The computer program GENHS was developed to
<br />produce a balanced hydrograph from known volumes and their
<br />associated time periods (e.g., 1-, 5-, 10-, 15-, 20-, 30~, 60-,
<br />90-days, etc.). The monthly depletion data were plotted to show the
<br />basic hydrograph shape. These monthly volumes were used as input to
<br />the program, GENHS, to generate a daily hydrograph of depletions.
<br />The resulting hydrograph was adjusted manually to equalize the
<br />beginning (January) and ending (December) daily depletions and to
<br />smooth the data. The daily depletions were subtracted from the
<br />100-year base snowmelt flood hydrograph to establish the depleted
<br />flow conditions. The resulting depleted daily flows and monthly
<br />volumes are presented in table 5.4. The 1985-1evel depleted
<br />100-year base snowmelt flood annual volume is 21,759,600 acre-feet.
<br />Monthly volumes, computed from the daily data, are slightly
<br />different from those computed from the monthly data because of the
<br />hydrograph shaping and smoothing process.
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