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<br />AREA
<br />1t1 20" deep x 50" wide
<br />112 27" X 63"
<br />.3 3.3" X 69"
<br />114 24" X 56"
<br />104" =26" 248"=62"
<br />4 "4
<br />Area = 26"X62" :: 1612 square inches
<br />1612 SQ,in ~ 144 sq,in,/sq,lt, = 11 _2square feet
<br />
<br />I
<br />
<br />
<br />All streams flow at dilfe-rent rates and with different volumes of water at various times,
<br />Wh.u might account for such changes?
<br />
<br />Tak.e a field trip loa stream. Select a stretch which is fairly straight and even flowing,
<br />Mark 3 check points. one at either end and one exactly in the middle, Using a float
<br />(a 2" styrofoam ball works well), drop il in far enough above the lirst dleck point
<br />to allow il to reach full....elQCily, Time its progress from Point A to Band B toC,
<br />Using an average between the two, calculate the velocity In leel , second, Next
<br />measure ttl"'depth and width ollhestream in several locations (ltl, 11I2, ate)
<br />and avera~'..: {hem to find the area, Consult the following lable lor the
<br />'tIeloclly coellicient and complete Ihe formula,
<br />
<br />Average slream
<br />depth in feet
<br />1
<br />2
<br />3
<br />4
<br />5
<br />6
<br />
<br />
<br />Velocity
<br />coefficient
<br />,66
<br />,68
<br />.70
<br />,72
<br />,74
<br />,76
<br />
<br />Velocity(ft,/second)
<br />X Coefficient X
<br />Area(depth X width)
<br />= Volume/second
<br />(measured in cubic feetl
<br />second), One cubic fOOl
<br />contains 7,48 gallons,
<br />
<br />
<br />Return at a later time and measure again, Did the
<br />flow increase or decrease?
<br />
<br />What do you think accounted
<br />for the change?
<br />
<br />Q
<br />
<br />
<br />o
<br />
<br />Although the
<br />formula appears
<br />complicated, it is
<br />not too difficult if each
<br />step is laken in order and
<br />carefully calculated, For
<br />e)(ample, lhe following
<br />computations were used to
<br />determine the stream flOw
<br />illustrated Ofl this page,
<br />
<br />VELOCITY
<br />A B = 25 feet in 10 seconds
<br />B C = 25 feet in 14 seconds
<br />50 24 =2,lft/sec:
<br />
<br />.68 1 428 ft.lsecond
<br />X COEFFICIENT = ADJUSTED VELOCITY
<br />
<br />1.428
<br />ADJ, VEL,
<br />
<br />x
<br />
<br />11,2sq,ft,
<br />AREA
<br />
<br />16cu,ft_lsec,
<br />VOLUME
<br />
<br />=
<br />
<br />16 cubic feet/second
<br />VOLUME/SECOND
<br />
<br />X 7.48gals,/cu.It,
<br />CONVERSION CONSTANT
<br />
<br />= t20gallons/second
<br />STREAM FLOW
<br />
<br />FIRST STUDY
<br />VELOCITY X COEFFICIENT = ADJUSTED VELOCITY X AREA = VOLUME/SEC,
<br /> X 7,48 Qats, leu,t!.
<br />VOLUME CONVEFlSION CONSTANT = STREAM FLOW
<br />SECOND STUDY
<br />VElOCITY X COEFFICIENT = ADJUSTED VELOCITY X AREA = VOLUME/SEe,
<br /> X 7,48gals./cu.ft. =
<br />VOLUME CONVERSION CONSTANT STREAM FLOW
<br /> 025
<br /> .,
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