. Bulletin. Agriculture; Agriculture -- Arizona. 74 Bulletin 86 losses in the Salt River Valley were reported in 1915 by the Recla- mation Service as 45 percent, and in 1917 as 32 percent. For small canals these losses are often over 5 percent per mile in adobe soil and 15 to 20 percent per mile in porous soil. An extreme case is shown in Fig. 3. Here the entire flow is lost. The ditch has a valuable water supply at its head and the vain effort is made to hurry the water over the sand on a steep grade. When the photo- graph was taken, the last drop of water was sinking away near the willow tre
. Bulletin. Agriculture; Agriculture -- Arizona. 74 Bulletin 86 losses in the Salt River Valley were reported in 1915 by the Recla- mation Service as 45 percent, and in 1917 as 32 percent. For small canals these losses are often over 5 percent per mile in adobe soil and 15 to 20 percent per mile in porous soil. An extreme case is shown in Fig. 3. Here the entire flow is lost. The ditch has a valuable water supply at its head and the vain effort is made to hurry the water over the sand on a steep grade. When the photo- graph was taken, the last drop of water was sinking away near the willow tree shown by the arrow, while three miles away alfalfa and other crops dependent on this stream were drying up and dying. In southern California there are extensive distribution systems. Fig. 3.—Small irrigation ditch near Tucson, showins- less of entire How by seepage. (From Bulletin 55.) that are piped throughout so that the loss of water in distrilnition is practically nothing. As a result of this and other economies the duty of the water is nearly nine acres per (Arizona) miner's inch of flow. The average duty of water in southern Arizona can be in- creased greatly by the use of cement pipe for small ditches and con- crete linings for larger ditches and canals. There are additional reasons for the use of cement pipe for irrigation ditches. The maintenance of open ditches is difficult. Under the subtropical skies of Arizona, weeds and algae grow rankly and occupy the whole cross-section of the ditch. Bermuda and Johnson grass thrive along the banks. Unless this vegetation is. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original University of Arizona. Agricultural Experiment Station. Tucson : Agricultural Experiment Station, University of Arizona
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