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Like all analytical solutions, this method is based on the following idealized assumptions: <br />The aquifer is homogenous and isotropic. <br />? <br />The extent to which a ?mound? in the ground water table is built-up from deep percolation is <br />? <br />small compared to saturated thickness. <br />The stream is in constant hydraulic connection with the alluvial aquifer. <br />? <br />Flow is one dimensional from the irrigated field to the stream. <br />? <br />Irrigation Return Flow Analysis <br />For the CRDSS river basins, there is limited hydrogeologic data available as required by the Glover <br />method to estimate the timing of irrigation return flows. In a reconnaissance-level study of the ground <br />water resources in the Gunnison and Crested Butte area conducted by the U.S. Geological Survey (Giles <br />1980), the alluvial hydraulic conductivity was estimated to range from 5 to 100 feet per day, with alluvial <br />thickness ranging from 20 to 70 feet. Local hydrogeologic properties can vary greatly within a relatively <br />small area. <br />Because of the variable nature of hydrogeologic properties and the lack of detailed, reliable data, <br />reasonable ranges of values for the required Glover parameters were adopted that will encompass the <br />expected values of hydrogeologic properties on Colorado's Western Slope. Table 1 summarizes the <br />range of values assumed for the Glover parameters for purposes of estimating the timing of irrigation <br />return flows. <br />TABLE 1 <br />VALUES ASSUMED FOR GLOVER PARAMETERS <br />GLOVER PARAMETERVALUE <br />Hydraulic Conductivity, K20 to 80 feet/day <br />Saturated Depth, D70 feet <br />Voids Ratio, V0.20 <br />Distance from stream, w1,000 to 10,000 feet <br />Assuming these hydrogeologic parameters, application of the Glover formulas resulted in three relatively <br />unique timing patterns for irrigation return flows. These return flow timing patterns are largely a <br />function of the values assumed for hydraulic conductivity and the distance from the stream (factors that <br />can be expected to vary significantly from ditch structure to ditch structure, even within the same basin). <br /> Table 2 presents a summary of the three irrigation return flow patterns. <br />2 <br />A275 01.09.95 1.15-17 Hyre, Fosha <br />