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<br />describe the boundary geometry confining the flow. <br /> <br /> <br />There are many ways to formulate a solution technique which <br /> <br /> <br />employs the standard step method. The primary objective, however. is <br /> <br /> <br />. to minimize the time required to solve the set of equations subject <br /> <br /> <br />to maintaining an acceptable accuracy in the calculated result. This <br /> <br />requires a maximum spacing between cross sections and a minimum nur~er <br /> <br />of iterations for converging the trial and calculated water surface <br />elevations. A second Objective is to minimize the time required to <br />prepare data describing the various functional relationships. It is <br />necessary to formulate a solution technique that can analyze the <br />entire range of possible discharges with only one set of cross sec- <br />tional data. In some cases all flow will be conveyed in the main <br />channel, while in others both channel and flood plain areas will <br />convey flow. <br />The following sections in this Chapter discuss the requirements <br />for determining representative values of area. wetted perimeter. <br />hydraulic roughness, reach length and velocity for the above flow <br />conditions and will present techniques to accomplish these Objectives. <br />Each of the functional relationships (5-2) through (5-8) is discussed. <br /> <br />Section 5.02. Averages from Distributed Parameters <br /> <br />The primary consideration in applying one-dimensional theory to <br /> <br />the calculation of water surface profiles in natural rivers involves <br />converting hydraulic parameters. which are distributed across complex <br />sections. into averages. In applying the energy equation, 5-1, flO\~ <br /> <br />5.02 <br />