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<br />VII I. FLOOD DISCHARGES <br />The hydrographs from the i!1dividua1 subbasins have been routed along the <br />watl!rcourses to the various design points. <br />Channel routi ng has been accompli shE!d usi ng the Mus ki ngum procedure <br />(a 'I inear ana1ys'is) for the reaches with minor overbank flow storage. The <br />Musld ngum parameters have been selected to account for conditi ons exi s ti ng <br />in ':he localized reaches of the channel. The condition varies from watercourses <br />exh'i biti ng substanti al overbank storage to the i nci sed channel s where vi rtua 11y <br />flO overbank storage occurs. This procedure simulates effects of prism and <br />wedlje storage with the channel and overbanks. <br />A full description of the Muskingum channel routing procedure may be <br />found in Routing of Floods Through River Chal~.!1!~~, Corps of Engineers <br />eng'i neering manual EM-1110-2-1408. <br />Four of the subbasins terminate at the south canal, where crossings are <br />pro'rided by siphons. At these locations, dUl= to the limited capacity of the <br />cro~; sing, runoff wi 11 be ponded temporar'j 1y dud ng the most intense runoff <br />per'i)ds. This ponding lowers the peak d'ischarlje rate and elongates the <br />flOlI hydrograph. To account for this result,~nt peak flow attenuation, <br />a Modified Puls Method reservoir routing will be performed at thE!se locations. <br />Two small subbasins (M-22, M-23) have b,een defined around two major <br />resl!rvoirs. Due to the limited basin size and reservoir capacity, the 100 year <br />event storm would result in a water surface rise of approximately one foot. <br />After a review of the hydrology, it was concluded that the reservoirs will <br />retain the tributary basin runoff, and are therefore not considered tributary <br />to '~he major basin flows. <br /> <br />17 <br />