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<br />. <br /> <br />. <br /> <br />. <br /> <br />DRAINAGE CRITERIA MANUAL <br /> <br />RUNOFF <br /> <br />Step 10. Repeat Step 5 for reach B-C. <br /> <br />4.13.3 Convex Routing Method <br />The convex routing method provides for some of the affects of channel <br />storage and, as a result, the storm hydrograph shape is modified in <br />translation along a channel reach. Similar velocity limiting considerations <br />need to be taken into account as discussed in 4.13.1. The recommended limits <br />for calculating the translation velocity for the convex method are given in <br />Table 4-5. <br /> <br />Table 4-5 <br />Recommended Limits for Calculating Translation <br />Velocity Using Convex Routing Method <br /> <br />Type of Channel <br /> <br />*Maximum <br />Flow <br /> <br />*Maximum <br />Froude No. <br /> <br />Natural Waterway 3/4 Q peak <br />Man Made: <br />Grass Lined 3/4 Q peak <br />Riprap Lined 3/4 Q peak <br />Concrete Lined 3/4 Q peak <br />* Use whichever results in lower velocity <br />**Applies only to channels built using USDcM <br />use F 0.95 <br /> <br />0.95 <br /> <br />0.80** <br />0.80** <br />No limit <br /> <br />limits, otherwise <br /> <br />Equation 4-7 is the basic equation for the convex method as described by Soil <br />Conservation Service (42). <br /> <br />O2 = (l-c)Ol + C II <br /> <br />(4-7) <br /> <br />In which, O2 = Outflow from the reach at the end of the unit time <br />increment (beginning of the next time increment). <br /> <br />01 = Outflow from the reach at the beginning of the time <br />increment. <br /> <br />5-1-84 <br />