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<br />...... <br />c.'1 <br />C,.H <br />C' <br />o {I~~ CHAPTER II <br /> <br />GRAND VALLEY RIVER BUDGET <br /> <br />.Using the the National Weather Service's Normal Annual Precipitation for <br /> <br />Colorado Map and the USGS daily data for West Salt Creek,. the ratio of the <br /> <br />mean annual volume of runoff to the mean annual volume of precipitation was <br /> <br />0.0023. When the ground water flow in the West Salt alluvium at the gage is <br /> <br />added, the ratio becomes 0.0025. Since the magnitude of the ungaged inflows <br /> <br />appeared to be very small, and therefore insignificant to the river budgeting <br /> <br />process, it was decided to assume a constant runoff per area factor for all <br /> <br />ungaged areas, based on West Salt's flow and drainage area. .It was then <br /> <br />attempted to extend West Salt's record by correlating to another stafion. In <br /> <br />order to preserve West Salt's statistical variance, it would be necessary to <br /> <br />transform both stations' records before correlating such that the transformed <br /> <br />~J.b <br /> <br />values would be normally distributed. <br /> <br />Unfortunately, due to the large percentage of zero flow months, no <br /> <br />transformation was found to make West Salt's flow anywhere near normally <br /> <br />distributed. .Abandoning transformations, it was then attempted to simply <br /> <br />correlate West Salt's flow to each of the surrounding USGS flow stations on <br /> <br />both a monthly and annual basis, with very poor results. Then a correlation <br /> <br />was attempted using West Salt's annual flow against the precipitation during <br /> <br />various portions of the year. The sum of December, January, and February <br /> <br />precipitation provided the best regression (coefficient of determination R2 <br /> <br />D 0.28) and was used to extend West Salt's annual flow record. The monthly <br /> <br />flows were estimated by assuming that each year's monthly distribution of <br /> <br />flow was the same as the average for the 6-year record. Because of the <br /> <br />scarcity of data, the surface water quality for the generated flows was <br /> <br />.'-:.' <br /> <br />',:'". <br /> <br />II-4 <br />