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Show 78 THE ALL-AMERICAN CANAL. losses could be reduced to 25 per cent. (SeeExhibit H of their report.) This seems to be a reasonable assumption when the maximum capacity of the canal is under consideration. Upon this basis, the maximum diversion at Laguna Dam would be 0.60 second-foot per acre, or a duty of 1 second-foot for 100 acres. BLOW SAND. . (a) The canal will have a length of 10.1 miles through the blow-sand section. The first 6i miles is through a region of low sand dunes and open mesa. The sand dunes do not exceed 12 to 15 feet above the mesa floor and are moving over the mesa in the general direction of northwest to southeast. The sand is of a very fine character, 99 per cent of which will pass a No. 50 sieve. The open mesas are of small area, except the last mile of this section, upon which there are very few sand dunes moving. The next 0.7 mile is mainly through a sand ridge, which reaches a height of 100 feet above the mesa floor on either side. This sand is of the same general character as the smaller dunes, but as a whole has a much smaller movement. For the next 1.4 miles the canal is through an open mesa with only here and there a small moving dune on its surface, but throughout this length it is flanked on both sides by high sand hills reaching an elevation of more than 200 feet above the mesa floor. The last If miles is across two main sand ridges, reaching elevations of 50 and 80 feet above the mesa floor, with practically no open mesa. The easterly one of these ridges consists of a number of more rapidly moving dunes upon the more stable sand of the two flanking hills mentioned in the preceding section. At this point the two flanking hills come together and completely cover the mesa floor. The last of these ridges contains a much coarser-grained sand on the surface, which requires a stronger wind to set in motion. (6) Early in the fall of 1918 a few areas and cross sections were selected and carefully mapped and measured in order to study the direction and rate of movements of the blowing sand. The test pits were also left open to catch the drifting sands and measurements made to detect the rate of filling up. In connection with these investigations the daily wind records of the United States Weather Bureau at Yuma, Ariz., for the past several years have been collected and plotted. The investigations have not as yet covered sufficient time to lead to definite conclusions upon the movement of the drifting sand, but the following general facts have been shown: 1. The fine sand on the eastern and central portion of the main sand ridge moves with winds exceeding 10 miles per hour, and on the west portion it takes a somewhat stronger wind to set the coarser-grained sand in motion, and there is a smaller quantity moved with a given wind velocity than on the central and eastern portion. |
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Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : California exhibits. |