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<br />Slope-area method of discharge measurement: A computational procedure whereby <br />stream discharge is calculated "on the basis of a uniform-flow equation involving <br />channel characteristics, water-surface profiles, and a roughness coefficient" <br />(Dalrymple and Benson, 1967). <br />Stream power: A measure of energy transfer of the flow. Stream power is computed as <br />62RSV, where R, S, and V are the hydraulic radius, in feet; water,surface slope, in feet <br />per foot; and mean velocity, in feet per second, respectively; and 62 is the specific <br />weight of water, Stream power also is defined as the energy dissipated per unit area of <br />streambed per unit time. <br />Subcriticalllow: If the 1I0w is subcritical, the Froude number is less than one and the <br />inertial forces are less than the gravitational forces. The flow depth in subcritical flow <br />is greater than the flow depth in critical flow, <br />SupercriticaI flow: If the flow is supercritical, the Froude number is greater than one and <br />the inertial forces are greater than the gravitational forces. The flow depth in <br />supercritical flow is less than the flow depth in critical flow. <br />Unifonn lIow: Flow of constant water area, depth, discharge, and average velocity <br />through a reach of a channel. <br />Velocity head: Represents the kinetic energy of the flowing fluid, generally expressed as <br />V'/2g, in feet, but actually is the energy per pound of flowing fluid, <br />Velocity-head coefficient: A factor used to adjust the velocity of the head computed from <br />the mean velocity in a channel section to give the true mean kinetic energy of the <br />flow for nonuniform distribution of velocities. <br />Wash load: The material which is transported by the river but is not found in significant <br />quantities in the bed material. <br />Water-surface profile: A longitndinal plot of the water,surface elevation as a function of <br />the distance downstream through a channel reach. <br />Wetted perimeter: The length of the line of intersection of the channel's wetted surface <br />with a cross-sectional plane normal to the direction of flow. <br /> <br />Contents IX <br />