Hydro-electric development on the Snake River at Oxen Bend, Oregon . om this record, the maximum flow over a period ofyears was determined to be about 70,000 cubic feet persecond. .ihe maximum amount of water used by the tur-bines is 6,500 cu. ft. per second. On account of thisvast quantity of water to be wastod, it was decided tobuild the entire dam a spillway. The main spillwaywhich is 393 fet ?ong will take care of the total70,000 seconds feet, and a shorter spillway at one sidewill act as a factor of safety in case of an unusualflood. P is essential to look out for floods in the•.-inake Ki
Hydro-electric development on the Snake River at Oxen Bend, Oregon . om this record, the maximum flow over a period ofyears was determined to be about 70,000 cubic feet persecond. .ihe maximum amount of water used by the tur-bines is 6,500 cu. ft. per second. On account of thisvast quantity of water to be wastod, it was decided tobuild the entire dam a spillway. The main spillwaywhich is 393 fet ?ong will take care of the total70,000 seconds feet, and a shorter spillway at one sidewill act as a factor of safety in case of an unusualflood. P is essential to look out for floods in the•.-inake Kiver Valley as the trees which help hold back thesprinr freshets are fast being removed, due to forestfires and ltiuobering. An earth retaining section, witha concrete core, has been constructed to prevent seep-age at the end of the dam. •Vith the assumption that the 393 feet of main spill-way takes care of the 70,000 cubic feet per second, thewater will rise to the height of feet above the is determined by Francis* formulaQ ? Lh | FIGURE I. -6- h?r ~ Q = = 85*8 StSS L 3.$* 79* h = ?hero h is the head of wate1 above the dam, in feet Q is the flow in cubic feet per second L is the length of the overflow Beotion, in feet. To obtain the smallest amount of action on thedam by the falling water and to obtain an extra a-mount of head in draught times, the section of thespillway should be the natural curve of water run-ning over a sharp edged weir. This section is shownin figure 1. Curve AB is an ellipse having a majoraxis equal to 2} = feet, and a min6r axis equal h _ 8 to i± ? SiBB i Curve BC is a parabola the equationof which is Xs = 8 pywhere p =.99 h so X2 = P. x .99 x y = ySolving this equation the following values of X and¥ were determined. 0 0 .89510 3,W 15 8 20 25 tft«8 SO 32 55 The next portion of the curve is a straight line, CD,drawn tangent to the parabola through the point M. in one extrenity of the base of the
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Keywords: ., bookcentury1900, bookdecade1910, bookidhydroelectri, bookyear1910
