Arizona republican., 1919-06-08
Pumping Plan to Solve Valley Drainage Problem
 Recommended as the Best

stances. it may prevent erosion or the growth of weeds and thereby greatly reduce the cost of cleaning and main taining canals. Requirements of this kind should be considered in connec- ton with those of preventing loss of water. Reference has already been made to underground waste from ir- rigaGon, which sinks into the soils and contributes to the rise in ground water
 In order to form an idea of what these underground losses are, it is necessary to study the amount of water which is applied to the land. In studying the use of water it is necessary to consider not only the quantity applied to the lands as shown by the water duty rec ords. based upon the deliveries to indi- vidual farms, but also the quantity of water delivered to canals less that wasted from the lower ends. All water which is delivered into the heads of main canals and laterals. unless car -ied away to the river as surface waste, sinks into the soils and become a part of the ground water of the valley.
 From the data at hand it is to be noted that the amount of water turned into the canals per year was suffi- clent to cover the total area irrigated under them from 3.8 to 5.4 feet deep.
 1t IS noted that there is a wide diff ference Between the quantity delivered to the heads of canals and that charged for at the farms. In terms of ouan- tity units this difference amounts to from 10000 to 10000 acre feet per year, This is important for the reason that measurements to canals show high or excess use of water while those at t%e farms show a moderate use. The methods of making measurements on
 the quantity of water delivered to the canals are such that we believe the re- suits to be reasonably accurate
 The natural explanation of this dis 1 crepancy IS that the difference was lost | by seepage and evaporation from the | canal and lateral system We believe | however, that the difference is greater than actual canal losses and that the | true explanation must be in the less ] accurate methods of making measure ! ments of water deliveries to individual | users on the farms-in other words | that the water actually charged for tc l individual users, has been less than the 1 quantities delivered. How much the 1 measurements made at the farms may | be in error, if is impossible to tell. In the use of water in irrigation il | frequently occurs that more is applied 1 at a single time than the soils can re- ! tain. The excess above the soil capa- | city is wasted over the surface or car 1 ried downward until it becomes a part 1 of the ground water below. The
 amount of water necessary to be ap- | piled at one time is the amount re. quired to moisten the soil sufficient fol
 plants to grow in it, to the depth the | plant roots will penetrate.
 It is impossible to compute the
 amount of waste which occurs in this
 manner for the reason that no record. | are kept of the areas to which a giver
 amount of water, delivered for irriga 1 tion, is applied. Some idea, however
 may be obtained of this loss from {
 few specific examples. In these exam.
 pies 1t has been assumed that the water delivered to an individual water useI
 was applied to his entire irrigable area 1 This assumption undoubtedly gives 7
 less depth than that actually applied since in most cases the entire area i: ! not covered at one irrigation. The re suits therefore represent the minimum amounts wasted, and it is probabl. that the actual amounts exceed thos, | shown. In these specific examples al l water delivered at a single irrigation il
 excess of that necessary to cover tn, | entire area to a depth of six inches, i.
 computed as waste. The results ar,
 shown in the following table: