Laserfiche WebLink
<br />. <br /> <br />24 <br /> <br />,. <br /> <br />. <br /> <br />Wr · Wet +WL + wm - Re'- dW~, <br /> <br />(2.5) <br /> <br />where Wr is the unit irrigation water requirement ,for the period being <br /> <br /> <br />considered, WL is the water required for'leaching, Wm is the miscellaneous <br /> <br />. <br /> <br />requirement, Re is effective rainfall, and dWs is the decrease in soil <br /> <br />~ter that can be utilized during the period. In the present estimation, <br /> <br />~ and, dWs are considered negligible. <br /> <br />, <br />2~7 Application Losses <br />Irrigation systems cannot apply water with perfect uniformity nor <br />without unavoidable losses, In sprinkler irrigation systems deep percolation, <br /> <br />surface runoff, and evaporation losses are among the components of water <br /> <br />. <br /> <br />losses. <br /> <br />. <br /> <br />,Unpublished experimental results by Colorado State University show <br /> <br />the basic intake rate of the soil near Cortez, Colorado, to be less than <br /> <br />~ , <br />0.5 inches per hour. For net irrigation application of 3 inches or less, <br />", <br /> <br />. <br /> <br />~'. <br /> <br />a farm efficiency of 65' was selected on the basis of recommendations by <br />, / <br /> <br />USDA-SCS (1960). <br /> <br />2.8 Distribution System ~osses <br /> <br />. ' <br /> <br />In addition to the application losses, there are losses that occur <br /> <br />in the storage and distribution systems. A substantial portion of the <br /> <br />~off and deep percolation losses may be recovered for use within a <br /> <br />project or for projects downstream. However, the topography and avail- <br /> <br />ability of collection and conveyance systems preclude allowance for <br />redivertible flows within this project and for downstream projects. Some <br />of the losses are illustrated in Figure 2;1 (Jensen, 1967). <br /> <br />. ,'# <br />