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<br />Design Hydrographs <br /> <br />In the Phase A report., .3 tabulati.on of the maximum flows for <br /> <br /> <br />2-, 10-, and LOO-year storm frequencies at each design point were pre- <br /> <br /> <br />sented for both present and future develc)pment conditions. These are <br /> <br /> <br />again presented in Table 11-2 and 11-3 cespectivelyc For preliminary <br /> <br /> <br />designs, final hydrology st.udies were ca]~ried out and the hydrographs of <br /> <br />the LOO-year flood under future development conditions at each of t~, <br /> <br /> <br />design points were prepared. These hydrog:r3phs are shown on Drawings 5 <br /> <br /> <br />through 8 in Volume II of this reporL Pea k flows for these design <br /> <br /> <br />hydrographs a:re shown in Table II-4c Ttwse flO\,. have been approximated <br /> <br />to tie nearest 10-, 50-, and 100 cfs for peak flows less than 200 cfs, <br /> <br /> <br />betw,een 200 and 2,000 cfs, and greater than 2,000 cfs respectivelyc <br /> <br />lle siJ;[)_C:':!1:.<'J~ia <br /> <br />The detailed design criteria used in this study is basically the <br />same as that given in the Urban Storm DrElinage (:riteria Manual. <br /> <br />The design philosophy used in this study va:cied from one reach to <br /> <br /> <br />another depending on the type of improvements proposed for that readL <br /> <br />Basically, it was asswned that all structures must pass a :lO-year storm <br /> <br /> <br />without damage. If an existing structurE~ '.laS found to be undersized for <br /> <br /> <br />a lO..year flood, the decision to upgrade the structure to accommodate a <br /> <br /> <br />higher frequency flood was dependent on i nCJ:.-emental cost, type of adj a~ <br /> <br /> <br />cent development, importance of the transpoJ:."tation route and magnitude <br /> <br />of p()ssible damage. <br /> <br />Chapter III presents a detailed discus.ion of the design criteria <br /> <br /> <br />and philosophy used for different reaches of the creek. <br /> <br />!:!Y~ a u Li:_~__~~~~,l c !:~~~:~E~~ <br /> <br />The adequacy of preliminary solut ions [or channel improvements '~'as <br />verified using the UcSc Corps of Enginee,'. computer program HEC--n, <br />Water Surface Profiles. The program computes the water surface profile <br />for !'iver channels of any (:ross seetioll for flows greater or less than <br /> <br />Il-ll <br />