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<br />46
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<br />J.D. RHOADES
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<br />TABLE 3
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<br />Results of simulation un9.er conditions of Strategy IIIj drainage from bean, alfalfa and wheat crops
<br />used to irrigate cotton; drainage water from cotton not discharged back to the river system.ll
<br />
<br />Crop \'et L ECiw Viw EC. V.. ECdw Loss
<br /> in yield (%)
<br />First project (volume of iiver=500; Ec=0.5 dS/m)
<br />Beans 25 0.2 0.50 31.25 0.64 6.25 2.50 0 ,t-
<br />Alfalfa 40 0.1 0.50 4.44 0.94 4.44 5.00 0 :~:
<br />Wheat 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Cotwn 14.4 0.15 3.15b (16.94)' 4.76 2.54 21.0 0
<br />Second project (volume of river=393.06; EC =0.5 dS/m)
<br />Beans 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Alfalfa 40 0.1 0.50 44.44 0.94 4.44 5.00 0
<br />Wheat 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Cotwn 14.4 0.15 3.15b (16.94)' 4.76 2.54 21.0 0
<br />Third project (volume ofriver=286.12; Ec=0.5 dS/m)
<br />Beans 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Alfalfa 40 0.1 0.50 44.44 0.94 4.44 5.00 0
<br />Wheat 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Cotwn 14.4 0.15 3.15b (16.94 )' 4.76 2.54 21.0 0
<br />Fourth project (volume ofriver= 179.18; Ec=0.5 dS/m)
<br />Beans 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Alfalfa 40 0.1 0.50 .44.44 0.94 4.44 5.00 0
<br />Wheat 25 0.2 0.50 31.25 0.64 6.25 2.50 0
<br />Cotwn 14.4 0.15 3.15b (16.94 )' 4.76 2.54 21.0 0
<br />
<br />Remaining volume of river = 72.24 units; EC = 0.5 dS/m
<br />Drainage volume to be disposed of in each project is 2.54 units; Ec=21 dS/m
<br />
<br />.llVolume diverted from river for irrigation in each project = 106.94 units.
<br />"The weighted average EC of the drainage waters from the bean, alfalfa and wheat crops,
<br />cThe cumulative volume of the drainage waters from the bean, alfalfa and wheat crops.
<br />
<br />quently used to irrigate typical field crops, can be avoided by intercepting the
<br />drainage water, isolating it from the good-quality water and reusing it for the
<br />irrigation of salt tolerant crops in the same project. In this latter strategy (III),
<br />not only is the loss in crop yield that results under conventional management
<br />(strategy 1) avoided but also the salinity of the river is maintained at a uni-
<br />formly low level (0,5 dSjm in this case) throughout its entire length, so that
<br />. all users have water of equal quality no matter whether they farm in the up-
<br />stream or downstream sections of the river, In this strategy (III), not only can
<br />reuse of the drainage water for irrigation be made without any loss of crop yield,
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