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<br />"'. <br />,<.., <br /> <br /> <br />.93 <br /> <br />"", <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 />