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<br />standard project depths for the drainage area size and for each of a <br />representative set of durations. <br />e. By studies of rainfall-runoff relations in the basin or near- <br />by, develop for each subarea a unit hydrograph, loss rates and base <br />flow that are representative of those for the most severe floods of <br />record. Techniques are discussed in Volume 4. Reconstitution of a <br />major rainflood is illustrated in figure 3.04. <br />f. Determine routing characteristics and coefficients for reser- <br />voirs and river reaches pertinent to the stu~. <br />g. Using runoff computation techniques described in Volume 4 and <br />routing techniques described in Sections 2.11 and 2.12 herein, compute <br />the standard project flood hydrograph for the design location. <br />h. Computations described through step g are usually confined to <br />a duration of 3 or 4 days. Where appropriate, a series of floods can <br />be computed as described in Section 3.08. These are illustrated in <br />figures 3.05 and 3.06. <br /> <br />Section 3.10. S..-ary of PrOCedu~';'sD_lt floods <br /> <br />The standard project snowmelt flood for a specified location can <br />be computed as fOllows: <br />a. From records of snowpack water equivalent or a combination of <br />winter snowfall and winter snowpack losses, determine the maximum snow- <br />pack water equivalent that would occur at the various points within the <br />drainage basin if the most severe snow accumulation conditions of the <br />entire region over a long period of time (40 or 50 years) should occur <br />over the specific basin. This may require some generalized estimates <br />of snowpack variations and an upward adjustment of snowpack quantities <br />if records are short. <br />b. Adopt either the degree-day or energy-budget melt computation <br />technique, depending on the adequacy of available meteorological data. <br /> <br />3-13 <br />