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Show PROBLEMS OF IMPERIAL. VALLEY AND VICINITY. 67 the sluice gates will be opened and the sand which has been deposited in the desilting chamber will be scoured out. It is proposed as a part of the Ail-American Canal work to allow space for a fourth Stoney gate inshore from those now in use. The desilting basin will be widened and extended farther upstream. It will be confined between two rock-fill training walls, which, while gradually spreading apart, will curve out toward the river so as to leave a wide, open mouth for the inflow of the canal water. The present headgate will be replaced by a new structure similar in type, having a length of about 1,374 feet. The upstream portion of this headgate will be constructed while the present one remains in service, and later the upper end of the new gate will be put into use during reconstruction of its lower end. Based on the experience thus far at the Laguna Dam, it is estimated that for desilting operations an amount of water not in excess of eight hours per week of the canal's flow will be required. Whether the desilting operation will be undertaken once a week or more frequently will depend not alone on the rate at which sand accumulates in the desilting channel, but also upon the effect which the resulting irregular flow m the canal will have upon the development of power and on the demands of the irrigators. THE CANAL FROM LAGUNA DAM TO THE SIPHON DROP. For 10.2 miles from Laguna Dam the canal will carry 10,600 second-feet of water, for both the Yuma project and the Imperial Valley, in the enlarged Yuma Canal. At the lower end of this 10-mile stretch on the present canal is a structure known as the siphon drop, through which the Yuma project water dreps about 10 feet to the lower level, at which it flows across the submersible river lands to the bank of the river opposite Yuma. The 6-foot superelevation of the canal banks will be such that with perfect safety the ordinary water-surface elevation could be increased. Furthermore, the operation of the system will probably require that dredges be kept in operation at certain points of the canal, and these can at any time when the necessity therefor is apparent be used to enlarge the canal prism and increase its capacity. The canal is to have a bed width of 162 feet. Its side slopes are planned at 1 to 1^ on the land side and 1 to 2 on the river side. When flowing full, the depth of water will be 16 feet. Its gradient will be 0.000079, or a little over 5 inches per mile. It has been so dimensioned that when flowing at capacity the mean velocity will be about 3.5 feet per second and that when its flow falls to one-half of the rated capacity the velocity will be at least 2.5 feet per second. .The enlargement of the Yuma project canal from its present dimensions is to be accomplished chiefly by raising the water surface and excavating in the bottom and on the land side of the present canal and placing the excavated material for the most part on the river side of the canal A high, broad bank of earth will thus be provided, on which there should be both road and railroad track. Within about 1| miles downstream from the Laguna Dam there will be three Stoney gates placed in this canal embankment, which are to serve as ,sluice gates and as waste gates whenever occasion may arise. They will discharge back into the river and, together |
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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] : |