OCR Text |
Show RETURN WATER Practically all of the rice projects have already completed, or shortly will complete, comprehensive and detailed drainage systems, which return the excess or unused water by direct and closely defined channels back into the Sacramento River. These drainage channels, especially as they go through the irrigated areas, are quite generally operated with the water surface below the adjacent ground water level, and hence the excess water loses nothing from seepage while being returned to the Sacramento River. Other transit losses, such as evaporation, are clearly so negligible as to be of academic interests only. Quite likely they would be less in the dredged drainage canals than in the River, if the same water were allowed to flow down its natural course. That this conclusion is not theoretical, is clearly demonstrated in the typical rice operations of District No. 108, where all of the excess water is immediately concentrated at the drainage pumping plant, about 18 miles below the diversion point, and accurately measured, as returned to the River. In the 5 years, 1919 to 1923, inclusive, the head-works diversion were sufficient to cover the irrigated areas to an average depth (average of yearly depths) of 8.7 feet, and the excess not used and immediately returned to the River amounted to 3.9 feet in depth over the irrigated areas, leaving the net extraction from the river, equivalent to a depth of 4.9 feet. 1.60 1.40 1.20 1.00 .80 .60 .40 .20 .00 «___tlutv /3 in ^00+ f5 ~^ * -- Av. mtttr divrtmd per&hrx..BtSin. Av. mtor returned perMhrs- -4351* Av. Hater used per 3*ha--430m L 1 I 1 II 1 II ¦r ¦¦ wwrnv.-ir. •r n A- ¦ M ¦¦ ¦ in >¦ ¦ m w n ii i dm > wmm m ¦i 1 n r 1 ¦ \m ¦ ¦¦ '""-i1 r rn i i ii i 1 II .VAT b i M mW/MMM.WM mWi?li..%* >:.W mkm.iUi*uu£ti£cmmm iiil f/y i in i i ¦ MS'JME. 1 1 ¦ i i n :W/m, MM. &&. ...MMmmwMmw/M'M ¦ ¦ %?. ----- &!¦ 15 30 April 15 May 31 15 June 30 15 31 15 31 15 23 July August September Fig. 8. Typical rice irrigation in Sacramento Valley, River draft, consumption, and return. The maximum net extraction from the River occurred during the season of 1920 when the Water Masters were restricting diversions as much as possible, and the net extraction was 5.7 feet, the amount returned being only 1.6 feet. Exactly the same net extraction from this portion of the river was made during the season of greatest use, in 1923, when the gross headworks diversions exceeded that of 1920 by 3.3 feet, and the amount returned exceeded the return of 1920, by exactly the same amount. The net use cf water of 4.9 feet, agrees very closely with the experimental work described in Bulletin 325, of the Agricultural Experiment Station of the University of California, which concluded that 5 feet of irrigation water was sufficient for rice, on suitable soils. |
Source |
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. |