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<br />Lesson 2 <br /> <br />Basic Hydraulics - Participant Workbook <br /> <br />The use of the slope-area method depends upon an assumption of uniform flow <br />in the channel. The analysis is based on the Manning's Equation. <br /> <br />b. Step-backwater Method <br /> <br />The step-backwater method can be used to develop gradually varied <br />backwater profiles which can be used to define a stage-discharge <br />curve. <br /> <br />2.9 PRACTICAL APPLICATION OF THE MANNING'S EQUATION <br /> <br />SINGLE SECTION <br />SLOPE-AREA METHOD <br /> <br />. DEFINE GEOMETRY, SLOPE, n-VALUES <br />. APPLY ARBITRARY WATER SURFACE <br />ELEVATIONS <br />. MANNING'S EQUATION FOR Q <br />. PLOT PAIRS OF ELEVATION/DISCHARGE <br /> <br />2.25 Single Section Slope-Area Method <br /> <br />Most culvert designs merit a relatively simple approach for estimating stage- <br />discharge relations. The single section slope-area method, based on the <br />Manning's equation, is straightforward and simple. <br /> <br />A. General Approach <br /> <br />Manning's equation does not always allow a direct solution of depth of flow, <br />given the discharge. For this reason, either an iterative or graphical solution <br />may be necessary. The stage-discharge curve represents a graphical <br />solution. <br /> <br />B. Slope-area Procedure Illustration <br /> <br />. Using a typical representation of the channel downstream of the culvert, <br />define the geometry, longitudinal slope, and roughness characteristics. <br /> <br />2-16 <br /> <br />I <br />I <br />I <br />,~ <br /> <br /> <br />,I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />