Laserfiche WebLink
<br />DRAINAGE CRITERIA MANUAL <br /> <br />RUNOFF <br /> <br />. <br /> <br />rainfall and not the beginning of rainfall. This is important <br />when routing and adding several hydrographs from different <br />basins. When routing hydrographs it may be necessary to adjust <br />the start of each hydrograph so that they are all consistent <br />with the beginning of rainfall. <br /> <br />4.13 Channel Routing of Hydrographs <br />Whenever a larger or a non-homogeneous watershed is being investigated, <br />it is necessary to segment the watershed into smaller and somewhat homogeneous <br />sub-basins. The storm hydrograph for each sub-basin can then be calculated <br />using the procedures discribed in 4-12. It is up to the investigator to route <br />and combine the individual sub-basin hydrographs to calculate a storm <br />hydrograph for the entire watershed. There are several methods commonly used <br />in channel routing that include: <br />a. Direct Translation <br />b. Convex <br /> <br /> c. Muskingum <br />. d. Storage - Di scharge (Modified Puls) <br /> e. Kinematic Wave <br /> f. D iffus ion Wa ve <br /> <br />g. Dynamic Wave <br />Only the Direct Translation and Convex methods will be presented in <br />detail in this section. The last three methods are probably the most accurate <br />of the routing techniques; however, they require a high speed computer to use. <br />The Muskingum method is simil ar to the Convex method and the Storage - <br />Discharge (Modified Puls) method is less convenient for hand calculations than <br />the Direct Translation or Convex methods. <br /> <br />4.13.1 Direct Translation <br />In the direct translation method of routing, the hydrograph is merely <br />shifted in time to account for the travel time along a watershed reach. The <br />shape of the hydrograph is not modified. <br /> <br />. <br /> <br />In calculating the translation velocities, check <br />number is appropri ate for the type of wa terway <br /> <br />to make sure <br />being used. <br /> <br />the Froude <br />Tabl e 4-2 <br /> <br />5-1-84 <br />