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<br />. <br /> <br />"1 f) j~'" ,...... <br />1I0JJ <br /> <br />occurring within any of a series of ten bands paralleling the river. <br /> <br /> <br />The width and distances of these bands from the river vary due to <br /> <br /> <br />inhomogeneities in the aquifer system. Exhibits 2 and 3 show the monthly <br /> <br /> <br />distribution of percent depletion or accretion for a band close to the <br /> <br /> <br />river and a band farther from the river respectively. Exhibit 4 is a <br /> <br /> <br />composite of accumulated accretion or depletion for all bands. The curves <br /> <br /> <br />show that drain-out is rapid for areas nearest the river (low band numbers) <br /> <br /> <br />and decreases rapidly for areas farther from the river (high band numbers). <br /> <br />I. <br /> <br />Using the curves mentioned above, the accumulated amount of drain-out <br /> <br /> <br />at the end of a seven-month irrigation season has been estimated to be <br /> <br /> <br />29,700 acre-feet for an entirely new conveyance and recharge system. This <br /> <br /> <br />is based on the assumption that recharge occurs at the beginning of the <br /> <br /> <br />irrigation season and no pumping occurs during the irrigation season. This <br /> <br /> <br />amount of drain-out was assumed to represent the non-recoverable losses <br /> <br /> <br />that would occur during the irrigation season and was added to the farm <br /> <br /> <br />delivery requirement of 52,100 acre-feet. This yielded an annual river <br /> <br /> <br />diversion requirement of 81,800 acre-feet. <br /> <br />If the existing conveyance facilities could be used for the diversion <br /> <br /> <br />of recharge flows, 97,300 acre-feet would need to be diverted from the <br /> <br /> <br />river annually to meet the average demands for supplemental irrigation water <br /> <br /> <br />at the farm headgates. With this scheme, annual drain-out losses would be <br /> <br /> <br />45,200 acre-feet. These losses are higher than they would be for the en- <br /> <br /> <br />tirely new conveyance system, because recharge using existing facilities <br /> <br /> <br />would occur closer to the river than it would with the new system, <br /> <br />- <br />"I <br />-I: <br /> <br />Based on a combination of new and existing water conveyance facilities, <br /> <br /> <br />an average annual river diversion of 87,300 acre-feet is required to meet <br /> <br /> <br />the on-farm requirements. The combination system uses existing canals in <br /> <br /> <br />test areas I, II, and III (these test areas will be described later in the <br /> <br />text; see the section entitled, It!techarge Potential, Test Areas" and uses <br /> <br />'new canals for the remainder of the study area. Drain-out losses for this <br /> <br /> <br />scheme average 35,200 acre-feet annually, <br /> <br />. <br />