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<br />\ <br />-----j <br />, <br />\ <br />c, ~cJ. <br />~~J <br /> <br />of adjacent sections are averaged to calculate losses through the <br />reach. This volume generally describes computation schemes based on <br />the latter condition; therefore, equations are developed for cross <br />sections located to define break points in widths and bottom slopes. <br />The objective of either computation scheme is to describe flow <br />boundaries accurately enough to predict energy losses due to friction <br />and eddy currents. The fewer the number of cross sections that are <br />available and the further apart they are located, the greater is the <br />amount of engineering judgment that is required to satisfactorily <br />analyze the problem. Any deviation from a smooth profile must be <br />explained. and in some cases it can be traced back to an inadequate <br />description of boundary geometry. The following points will be helpful <br />in developing the geometric model. <br />On the best available map locate cross sections to be surveyed <br />such that the following information can be described for field personnel. <br />a. Cross sections are needed at sharp changes in bed slope. <br />b. Cross sections are needed at points of contraction or expansion <br />of the channel. <br /> <br />, <br />, <br /> <br />c. Cross sections are needed in tributaries immediately above <br />a confluence and in the main stream immediately below a confluence. <br />d. Cross sections should be spaced to provide a reasonable <br />transition between locations that have different roughness characteristics. <br />e. Cross sections are required immediately above and below control <br /> <br />sections such as weirs. <br /> <br />f. The maximum elevation of each end of a cross section should be <br /> <br />higher than the anticipated maximum water surface elevation. <br /> <br />4.03 <br />