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<br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />COD:5b <br /> <br />are usually required to force the water to the higher elevations and <br /> <br /> <br />field runoff commonly results. With proper design and location of field <br /> <br /> <br />ditches the tail water may be picked up and redistributed to maintain <br /> <br /> <br />relatively good efficiency. When fields are of moderate and uniform <br /> <br /> <br />slope in one direction, the border dike method of flood irrigation can <br /> <br /> <br />be utilized to provide very high field efficiencies. Again, however, the <br /> <br /> <br />result is largely governed by how well the irrigator controls the stream <br /> <br />size, by the width and length of the border strips and by the time of set. <br /> <br />Application efficiency when using furrow irrigation may also vary <br /> <br /> <br />appreciably. If the furrows are directed down steep slopes it is diffi- <br /> <br /> <br />cult to prevent field runoff, Contour furrows, running in general across <br /> <br /> <br />slope, greatly increase the potential for uniform application of the <br /> <br />desired water depth. Close attention to water control and proper field <br /> <br /> <br />layout are essential. <br /> <br /> <br />Sprinkler irrigation provides the best method for water control and <br /> <br /> <br />uniform application, especially on lands of variable topography and soil <br /> <br /> <br />characteristics. Caution is required, however, to prevent application <br /> <br />rates in excess of soil intake rates, If this occurs, runoff results <br /> <br />and attained efficiencies may be considerably below attainable efficiencies. <br /> <br /> <br />Thus, the sprinkler systems which are common to Eastern Colorado (i.e., <br /> <br /> <br />center-pivot systems), with their inherent high application rates, are <br /> <br />limited to the coarser textured soils which have high infiltration rates. <br /> <br />Whatever method of irrigation water application is employed, certain <br /> <br /> <br />precautions and design techniques may be used to improve efficiency. <br /> <br /> <br />Proper farm ditch locations, field design, stream size and cut-back <br /> <br /> <br />techniques can be specified by trained irrigation technicians. Collection <br /> <br /> <br />of runoff water into ditches for subsequent redistribution or into tail- <br /> <br /> <br />water reuse pits, where it can be pumped back to the upper end of the <br /> <br /> <br />field or directed to another field, is becoming increasingly popular with <br /> <br /> <br />concerned irrigators. <br /> <br />-9- <br />