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<br />The extent to which attenuation of the peak flow occurs is influenced by the <br />travel time for the flood before encountering the CRITICAL SECTION. Remember, <br />the CRITICAL SECTION is the location downstream where manmade i~rovements are <br />set close to the stream channel and thus where property damage or loss of <br /> <br />human life would most likely occur. Since routing effects reduce the <br />hydrograph peak as distance downstream of the dam increases, critical sections <br />nearer the dam tend to control'the hazard classification. The process of <br />identifying the critical section is judgemental and often requires checking <br />several suspect locations. <br /> <br />Many recognized methods of flood routing are available to predict routed <br />hydrograph shape. While all techniques are considered acceptable for the <br />purpose of determining hazard, the discussion will be limited to the ''method <br />of successive averages".[Z] The method of successive averages can be used to <br />easily determine the routed hydrograph peak value, Qr, without the need to <br /> <br />generate a completed hydrograph. In brief, the method determines the degree <br />of routing (Le., flood peak reduction) as a function of the following: <br />Travel time for the peak <br /> <br />Channel slope <br />Channel roughness <br /> <br />Channel geometry <br />Base time of the failure hydrograph <br /> <br />This routing method is best explained by example. Refer to Worksheet W-Z <br />enti tIed ''Routing Loss Calculations", page 15, completed for Mason Reservoir <br /> <br />10 <br />