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<br />~ <br /> <br />e <br /> <br />INLET-CONTROL NOMOGRAPHS <br /> <br />Charts 1 through 7 <br /> <br />Instructions for Use <br /> <br />1. To determine headwater (HW), given Q, and size and type of culvert. <br /> <br />, <br /> <br />a. <br /> <br />Connect with a straightedge the given culvert diameter or <br />height (D) and the discharge Q, or.9 for box culverts; mark <br />B <br />intersection of straightedge on HW scaJ.e marked (1). <br />D <br />HW HW <br />If 15 scaJ.e marked (1) represents entrance type used, read 15 <br /> <br />on scaJ.e (1). If another of the three entrance types listed on <br />the nomograph is used, extend the point of intersection in (a) <br />horizontaJ.ly to scaJ.e (2) or (3) and read ~ <br />D <br /> <br />i <br /> <br />b. <br /> <br />c. Compute HW by multiplying HW by D. <br />D <br /> <br />2. To determine diSCharge (Q) per barrel, given HW, and size and type <br />of culvert. <br /> <br />. <br /> <br />a. Compute.!!!! for given conditions. <br />D <br />b. Locate~ on scaJ.e for appropriate entrance type. <br />(2) or (3) is used, extend ~ point horizontally <br /> <br />If scaJ.e <br />to scale (1). <br /> <br />c. (;onn"ct point on ~ scale (1) as found in (b) above and the <br /> <br />size of culvert on the left scale. Read Q or ~ on the dis- <br /> <br /> <br />charge scaJ.e. <br /> <br />d. <br /> <br />If .9 is read in (c) multiply by B (span of box culvert) to <br />B <br />find Q. <br /> <br />3. To determine culvert size, given Q, aJ.lowable HW and type of cul- <br />vert. <br /> <br />a. Using a trial size, compute HW <br />D <br /> <br />b. Locate ~ on scale for appropriate entrance type. If scaJ.e <br />D <br />(2) or (3) is used,extend HW point horizontally to scale (1). <br />D <br />c. Connect point <Xl ~ scale (1) as found in (b) above to given <br /> <br />discharge and read diameter, height or siZe of culvert required <br />HW <br />for -n value. <br /> <br />. <br /> <br />d. If D is not that originally assumed, repeat procedure with a <br />new D. <br /> <br />5-19 <br />