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<br />Water losses which remain on or beneath the soil surface are potentially <br />recoverable water supplies. Although changed in quality or accessibility <br />(location, cost of recovery 01 other constraints), such waters are not lost <br />or necessarily wasted. Tempo~ary water losses from irrigated agriculture to <br />runoff or deep percolation are potentially recoverable unless the water ends <br />up in a nonaccessible place or form (e.g. - a saline sink or aquifer). In <br />most irrigation situations, some over application of water is necessary in <br />order to flush salts or other materials in the irrigation water (Total <br />Dissolved Solids) below the effective root zone of the crops being grown. <br />This is called the "leaching fraction" and is just as essential to long-term <br />crop production as are the other crop requirements. <br /> <br />Certain water conservation measures for capturing and reusing recover- <br />able water losses in the High ,Plains irrigated areas are already widely in <br />practice (e.g. tailwater recovery systems). Many preventative practices are <br />also in wide use, such as the installation of buried pipe to replace open <br />ditch conveyance, irrigation system design to minimize runoff or deep per- <br />colation, and others. These practices should be expanded and improved to <br />capture or prevent a greater percentage of recoverable losses. There are <br />benefits to be achieved from reducing the volume and occurrence of "recover- <br />ab 1 e losses". Improved i rri gati on water management can reduce the costs <br />of secondary recovery of such losses (incl udi ng reduced energy requi rements) <br />and can also reduce the first cost of water application. <br /> <br />Although important to overall water conservation and efficiency objec- <br />tives, recoverable losses in irrigated agriculture are minor in comparison to <br />nonrecoverable losses. Evaporation and transpiration are the major factors <br />in nonrecoverable agricultural water losses, representing 60 to 80 percent of <br />total agricultural water use. The dominance of such "nonrecoverable losses" <br />makes their reduction the best opportunity for significant water savings in <br />irrigated agriculture. Even a small percentage improvement or reduction in <br />water losses to evaporation and/or transpiration may represent a more <br />substantial reduction in total water use than a relatively large change in <br />recoverable water losses or reduction in the quantity of such losses. <br /> <br />4 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />