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<br />Development of Randlett Flow Data to Early 1900s
<br />
<br />Extending the flow record for the Randlett gauge was accomplished by making a linear
<br />correlation with the Duchesne River at My ton stream gauge. The My ton gauge is located
<br />approximately 16 miles upstream of the Randlett gauge. The period of complete record for
<br />the My ton gauge is from 1912 to 1994. A coefficient of determination or R' of 0.972 was
<br />calculated for the correlation of concurrent monthly flows from 1943 to 1969, shown in
<br />Figure 4-16. Using the correlation, the Randlett flow record was extended by calculating
<br />monthly flows from 1912 to 1942. The extended record shows (approximately) a 20 percent
<br />increase in pre-project average flows with an average volume of 533,700 acre-feet. The
<br />extended flow record for Randlett is shown in Tables 4-6 and 4-7 and in Figure 4-17. Flow
<br />statistics for the various periods are summarized in the table below.
<br />
<br />Duchesne River at Randlett
<br />
<br />
<br />
<br />Period Oct Noy Dec Jon Mar Jun Jul Aug Sep Annual
<br />1912-1994 22,739 24,932 26,516 25,401 25,589 32,242 35,295 16,1n 16,882 478,932
<br />1912-1969 23,341 26,093 28,187 26,910 27,027 33,813 38,517 17,891 18,410 533,732
<br />1970-1994 21,342 22,238 27,820 12,201 13,336 351,796
<br />Period Oct Noy Jul Aug , Sep Annual
<br />1912-1994 370 419 431 413 457 524 2,260 574 263 284
<br />1912-1969 380 439 459 438 483 550 2,539 627 291 309
<br />1970-1994 347 374 368 356 397 465 1,615 ,453 198 224
<br />Hydrologic Effects
<br />
<br />The mean value from one period to another is subject to distortion of extreme values that
<br />may have occurred in a period due to hydrological effects. The hydrologic effects are the
<br />result of natural hydrological cycles independent of development. An attempt was made to
<br />remove the hydrological effects from the Duchesne River at Randlett for the post-project
<br />period so that an accurate estimation of project effects from diversions and depletions could
<br />be made, To remove the hydrologic effects, a correlation with other stream gauges not
<br />affected by diversion or depletions was made with the extended Randlett flow record.
<br />
<br />A good correlation would allow the pre-project flows to be extended through the post-
<br />project period. The correlation was made with the annual volume of flow for concurrent
<br />years prior to 1970 at the following gauges: Ashley Creek near Vernal, Whiterocks River
<br />near Whiterocks, Uinta River near Neola, Currant Creek near Fruitland, North Fork of Dry
<br />Creek, and Duchesne River near Tabiona. The results of the correlation are shown in
<br />Figures 4-18, 4-19, 4-20, 4-21, 4-22, and 4-23. The determination coefficients were calculated
<br />to be 0.763, 0.786, 0.737, 0.550, and 0.828 for Ashley Creek, Whiterocks River, Uinta River,
<br />Currant Creek, North Fork of Dry Creek, and Duchesne River near Tabiona, respectively.
<br />The correlations of the gauges were not satisfactory to extend the record of pre-project flows
<br />into the post-project period. The poor correlations were attributed mainly to the fact that
<br />the gauges not affected by diversions are located higher in the drainage basins.
<br />
<br />SlC\ 134107\REPT1.DOC
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<br />4.3
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