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<br />~ <br /> <br />I. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />!. <br />. <br />. <br />. <br />I. <br />I. <br />I. <br />'. <br />. <br />. <br />. <br />I. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br /> <br />Bosley Wash Drainage Master Plan Phase I: Watershed Floodplain Delineation <br />_ ~__,tY:~~:?;~\;~0C0:l";~~ ,~'~ <br /> <br /> <br />4,2 Hydrologic Routing <br /> <br />Hydrologic channel routing was used within HMS to compute channelized flow time, Different <br /> <br /> <br />routing methods were selected based upon the type of channel being modeled as well as the type <br /> <br />of data available, The Muskingum-Cunge routing method was used for all well-defined <br /> <br /> <br />manmade channel sections, The cross-section shape was approximated with a prism, Reach <br /> <br />length was calculated using measurements from the GIS mapping, Channel slope for the reaches <br /> <br />modeled hydrologically were determined using profile plots generated from the field survey and <br /> <br />GIS mapping contours, Bottom width and side slopes were estimated for the various reaches <br /> <br />based on the field survey and field observations, The Manning's 'n' value was assumed to be <br /> <br />0,035 for all man made channels, based on field observations and past experience, Table 3 <br /> <br /> <br />summarizes channel geometry used on the primary reaches for hydrologic and hydraulic <br /> <br />modeling, To model the north channel of Stub Ditch, the Muskingum-Cunge 8-Point method <br /> <br /> <br />was used, This allows entry of cross-sectional coordinates for irregular channel sections, <br /> <br />Table3 <br /> <br />Channel Geometry for Hydrologic Modeling <br /> <br /> <br />Stub Ditch,J 0,00069 <br />est Highline-J 0,0006 . · <br />osley Wash,J O,OJ9 2 J.45 <br />osley Wash,2 O,OJJ 6 0,66 <br />rice Ditch,J 0,0013 2 3,22 <br /> <br />West Bosley Drain,J 0,017 4 1.02 <br />Bosley Drain,J 0,0086 3 1.44 <br />osley Drain,2 0,0083 3 1.07 <br />appas Drain-2 0,01 3 1.25 <br />appas Drain 2-4 0,0048 3 1.35 <br />Henchy Waste,J 0,0082 5 1.54 <br />enchy Waste,2 O,OJ4 2 1.8 <br /> <br />'West Highline,J was modeled using the Muskingum Cunge 8 Point Method. <br />This method uses an eight point cross,section instead of a bottom width and <br />side slope. <br /> <br />IP <br /> <br />: (II ~_f:L~ itlli:~':Ji>:Z;:"V":j;'}<,{"" <br />(~ <br />~ <br /> <br />@~ <br /> <br />::14;.! <br /> <br />(",.~ <br />'5~~' <br />~~~';~'L~~~} <br /> <br />. <br /> <br />Page 12 <br />