. Principes de l'ingénierie de l'irrigation, les terres arides, l'approvisionnement en eau, l'entreposage, de barrages, de canaux, les droits de l'eau et de produits. Fig. C.-vannes en fonte sur la distribution de systèmes au lieu de l'habituel. woodengates Projet Uncompahgre, Colo. ^ ( ?18^^^^^- ?*** ? ^-*-."i"• ^^* * ,-^^&Lt ;-^^^s / SH ., , ; ? ? J'^^^H^^^^^^^^HIIII 1MO9H ? ? ? ?o^l^ ^H^^^^ - ?-- :. ? ? ^-^^ ?/U--^t^ ;^^^^^^t| ?,.^** ., .•."£" Fig. D.-Farmerswater sur gates enclins de dalles de béton. Bien RiverProject 111 systèmes de distribution, au Montana, qui peut être soulevée à la hauteur nécessaire pour passer le ofwater quantité désirée. Des structures plus permanentes de th

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. Principles of irrigation engineering, arid lands, water supply, storage works, dams, canals, water rights and products. Fig. C.—Cast-iron valves on distributing systems instead of the usual woodengates. Uncompahgre Project, Colo. ^ (?18^^^^^-?***? ^-*-.»~i»*^ *• ^ , -^<^-^ /^s^SH ., , ; ?? ^ I^^H^^^^^^^1mB9HIIII^H ????Y^l^ ^H^^^^ - ?--:.?? ^-?^/U--^t^ ;^^^^?^^t|, .^** ., .•.„£„ Fig. D.—Farmerswater gates on inclined concrete slabs. Sun RiverProject, Mont. DISTRIBUTION SYSTEMS 111 which can be raised to the required height to pass the quantity ofwater desired. More permanent structures of the same type areconstructed of concrete or other form of masonry, and the openingsclosed by means of metal gates. Another type consists of a coveredbox of wood or masonry carried through the banks and having theupper and lower ends protected so as to prevent erosion. (SeePlate VIII.) The forms of measuring devices commonly used are weirs, ratingflumes and some type of submerged orifice through which the flow. Fig. 2:^.—Plank measuring box with Cippoletti weir and automatic register. of water can be determined. Where there is suf&cient fall to permitits being used, the weir is perhaps the most satisfactory, cheap andsimple device for measuring relatively small flows, such as are com-monly turned into farm ditches and the smaller laterals and sub-laterals. For this purpose both the rectangular and Cippoletti weirsare used (Fig. 33). The latter type of weir possesses some advan-tage over the former as it is unnecessary to take account of endcontractions. A rating flume ordinarily consists of a square or rectangular boxopen at both ends and placed in the channel so as to form the water-way for a distance of several feet. The flume is first rated for 112 PRINCIPLES OF IRRIGATION ENGINEERING various depths of water flowing through it by means of current depthsof water flowing through it by means of current meters, weirs or othersuitable measuring devices. For convenie

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• bookcentury1900
• bookdecade1910
• booksubjectirrigat
• bookyear1913