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<br /> <br />passage of a high amplitude, low frequency <br />wave. As this wave moves downstream, <br />its shape broadens and flattens provided <br />there is no additional inflow along the <br />reach of the stream. This change in <br />shape is due to the channel storage be- <br />tween the upstream and downstream loca- <br />tions. If the wave encounters a signifi- <br />cant amount of storage at a given location <br />in the stream, ,such as a reservoir, the <br />attenuation of the flood wave is <br />increased. Figure II-4 depicts the effects <br />graphically. <br /> <br />Storage routing is the numerical trans- <br />location of a flood wave (hydrograph). <br />This process is applicable to reservoirs, <br /> <br />FLOW <br /> <br />Reservoir routing is dependent only upon <br />storage in modifying a flood wave. Channel <br />routing is dependent upon inflow and <br />outflow as well as storage in a stream <br />reach. Watershed routing incorporates <br />the runoff attenuating effects of the <br />watershed and is of importance in some <br />hydrograph generation methods. Reservoir <br />routing is of special interest in culvert <br />design, and it will be discussed further <br />in chapter V. <br /> <br />J <br /> <br />j <br />1 <br />. <br />j <br />1 <br />J <br />j <br /> <br />B. Site Data <br />1. General. The hydraulic design of <br />a culvert installation requires the eval- <br />uation of a large amount of data including <br />culvert location, waterway data, roadway <br /> <br />, <br />J <br />, <br />I <br />, <br />j <br />j <br />j <br />j <br />~ <br />j <br />, <br />~ <br />< <br />j <br /> <br />1 <br />, <br /> <br />; <br /> <br />. <br /> <br />DOWNSTREAM HYDROGRAPH (after channel rautinll)= <br />RESERVOIR INFLOW HYDROGRAPH <br /> <br />~ <br />~ <br />~ <br />, <br />~ <br />j <br /> <br />UPSTREAM HYDROGRAPH <br /> <br />, <br /> <br />RESERVOIR OUTFLOW <br />HYDROGRAPH <br />(ofter reservoir routinll) <br /> <br />, <br />. <br /> <br />TIME <br /> <br />~ <br />] <br />j <br /> <br />, <br /> <br />, <br /> <br />Figure II-4.--Flood hydrograph shape modification. <br /> <br />............ <br /> <br />channels, and watersheds. The effects <br />of the routing are threefold: volume <br />conservation, peak reduction, and time lag. <br />'......" <br /> <br />---......, <br /> <br />, <br /> <br />data, and the design headwater. Each <br />of these items and its importance is <br />discussed in the following paragraphs. <br /> <br />18 <br /> <br />, <br /> <br />. <br />-- <br />