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<br />. <br /> <br />\~ea,der. 'b,tural channels are rarely straight and uniform over <br />l:'::g s-:::~::y reaches. The ma\:iJnu:n allo\..-able average velocity C2J1 be <br />SC]C1S:ed for bends u51ng Figlr:-e 6 (Plate 34 of Reference 6) as a guide. <br /> <br />:; <br />r <br />L <br />~ <br />I <br /> <br /> <br /> <br />,- <br />I <br />r <br />I <br />I <br />21 <br /> <br />OJ <br />> <br />"- <br />" <br />> <br /> <br />WHERE: <br /> <br />R' WATERCOURSE RADIUS <br />W, WATER SURFACE WIDTH <br />UPSTREAM OF SEND <br />Vu= MAxn,J,L:M ALLOWABLE AVG. <br />VELOCITY IN A STRAIGHT, <br />U~',:iFORM CHA~JNEL <br /> <br />....'""':; ~/.AX~~.J,V,~ ALLCV,':"'S:"'E AVG. <br />u VELOClTY I~J A BEND <br /> <br />I <br />! <br /> <br /> <br />3 <br /> <br />4 5 <br />(REFERENCE 6) <br /> <br />R/W <br /> <br />Figure 6 <br /> <br />If scour and erosion are significant in the channel or flood <br />plain under nOTIT~1 conditions, floodways hnich would increase <br />velocities should normally not be considered. In such cases, the <br />entire IOO-year flood plain would be designated as "Fjlv" except for <br />minor emba}1TIents and other "dead" storage areas. <br /> <br />In cases l\nere normal velocities ,are non-erosive, care should <br />be used in final selection of floom,a)' to assure that associated <br />\~locities reT-ain in the acceptable ranges. The mean channel <br />veloci ties sho\\']1 in Figure 5 can be used as a gllide in determining <br />ma:x:i;;:u:n allOI\"able velocities. <br />