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<br />
<br />
<br />.93
<br />
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<br />'.'j
<br />
<br />1692
<br />
<br />OCTOBER 1973
<br />
<br />HY10
<br />TABLE 2.-
<br />
<br />~"
<br />
<br /> Average
<br /> velocity
<br />Particle Channel Water depth, Temperature, V, in Water surface
<br />size, d, width, W, 0, T, in degrees feet per slope
<br />in millimeters in feet in feet celsius second S x 103
<br />(1) (21 131 (4) 151 (61
<br /> (g) Williams'
<br />1.35 1.0 0.094-0.517 I 11.9-30.8 1.27-3.49 1.1-22.18
<br /> (h) Schneider's
<br />0.25 8.0 1.012-2.822 I 20.4-22.4 I 1.67-6.45 I 0.10-4.97
<br /> (i) Colby and Hembree's Field
<br />0.283 69-72 1.36-1.89 I 1.7-28.9 I 2.15-4.171 1.14-1.80
<br /> (j) Hubbell and Matejka's Field
<br />0.16-0.24 123-153 I 0.81-1.22 I 0.0-29.4 I 1.95-3.69 I 0.93-1.46
<br /> (k) Jordan's Ficld Data from
<br />0.21-0.78 \1.524-1.7461~~.5-49.9 1 1.7-27.8 J 2.04-5.37 L 0.043-0.099
<br />
<br />r
<br />
<br />~,
<br />S;',
<br />~.
<br />;;~
<br />'t;
<br />~.;
<br />,
<br />t
<br />
<br />\;
<br />
<br />(VS V c,S )
<br />log C, ~ 1+ J log -:- - --;;;- ..........,........... (23)
<br />
<br />,.
<br />i..,
<br />i'
<br />
<br />provides the best correlation between total sediment concentration C, and
<br />dimensionless effective unit stream power (VS/w - VcrS/w). In Eq. 23, I
<br />and J are coefficients. The dimensionless critical velocity, V cJ w, is determined
<br />by cithcr Eq. 18 or Eq. 19, dcpending on the value of shear velocity Rcynolds
<br />number.
<br />Only those field data in which the hydraulic and sediment measurements
<br />were made within a 24-hr period are tabulated in Table 2. For the Niobrara
<br />River, the hydraulic data were collected at a gaging station while the sediment
<br />data were collected at a nearby contracted section. The hydraulic and sediment
<br />data of the Middle Loup River were collected at Sections E and D, respectively.
<br />No total sediment concentration was measured from the Mississippi River, and
<br />it was assumed that the total sediment concentration can' be represented best
<br />by the measured bcd-material concentration. Since no water temperature mea.
<br />surement was made by Gilbert, a temperature of 200 C is assumed for all Gilbert
<br />data. The particle size, d, is the median sieve diameter of the sediment. Guy,
<br />Simons, and Richardson published their data in terms of fall diameter. The
<br />difference between these two measurements of particle size is insignificant when
<br />either one is smaller than 0.4 mm. The fall diameter is converted to sieve
<br />diameter in accordance with Fig. 7 of Report 12 of the Inter-Agency Committee
<br />on Water Resources (23). The fall diameters for the coarse sand are also shown
<br />in parentheses in Col. I of Table 2. The fall velocity of a given sieve diameter
<br />and water temperature is determined from Fig. 6 of Report 12.
<br />The values of I and J in Eq. 23, and the statistical parameters in terms
<br />of logarithmic units for all thc data arc tabulated in Cols. 8 through II. The
<br />
<br />~>,
<br />
<br />INCIPIENT MOTION
<br />
<br />Continued
<br />
<br />Total sediment
<br />concentration,
<br />Cl' in parts
<br />per million
<br />171
<br />Data (1967)
<br />16-15.570
<br />
<br /> Standard Correlation Number Standard
<br /> error, coefficient, of data, error
<br />I J " r N from Eq. 26
<br />(8) (9) (10) (11) (121 (13) :i
<br /> i
<br />
<br />5.381 [l.l731 0.240
<br />
<br />0.949 37 I 0.274
<br />0.960 31 L 0.222
<br />0.904 25 I 0.104
<br />0.676 15 I 0.190
<br />0.857 L~I 0.273
<br />
<br />I
<br />i
<br />j:
<br />
<br />Data (1971)
<br />18-17.152 I 4.834 ~I 0.171
<br />Data from Niobrara River (1955)
<br />392- 2,220 I 4.573 ~ 0.097
<br />Data from Middlc Loup River (1959)
<br />548- 2,440 I 4.208 1~1 0.166
<br />Mississippi Rivcr (1965)
<br />3- 226 --1 4.751 ~I 0.240
<br />
<br />low values of standard error of estimate C1 and high values of correlation coefficient
<br />. rindicate good agreement between Eq. 23 and the measurements. The weighted
<br />average value of (T and r, based on the number of data, for the 1,093 sets
<br />of laboratory data are 0.13 and 0.97, respectively. The correlation might be
<br />improved even further if the actual temperatures of Gilbert's data were given
<br />and the number of observations for some of the runs could be increased. The
<br />reason that field data obtained from the Middle Loup River and the Mississippi
<br />River do not provide as good agreement as other data is mainly due to the
<br />diversified particle sizes, water temperature, and water depth involved in the
<br />regression analyses. The effects of the variations of these parameters on the
<br />total sediment concentration will be studied in the following section.
<br />
<br />i ~
<br />
<br />GENERAUZED EaUATION AND ITS APPUCATION
<br />
<br />A useful equation which can be used by engineers with confidence in predicting
<br />the total sediment concentration of an alluvial channel should satisfy the following
<br />requirements:
<br />
<br />1. The equation has some theoretical support.
<br />2. It is dimensionally homogeneous.
<br />3. It is thoroughly verified by both laboratory and field measurements that
<br />cover a wide range of variations in both flow and sediment conditions.
<br />4. The parameters used in the equation can be obtained from both laboratory
<br />flumes and natural streams without much difficulty.
<br />5. The computation is simple and straightforward.
<br />
<br />
<br />A review (40) of the published sediment transport equations reveals that most
<br />
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