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<br />Worksheet 3: Time of concentration (Tc) or travel time (Tt> <br /> <br />Project 5Pr.:j,<.J'<; G... <br />Location :::5T~1 -;;:- !.2e, o~ <br /> <br />BY~' <br /> <br />Da te .)19.0 <br /> <br />Checked <br /> <br />Date <br /> <br />Circle one: Present Developed <br />Circle one: Tc Tt through subarea <br /> <br />NOTES: Space for as many as two segments per flow type csn be used for each <br />worksheet. <br /> <br />Include a map. schematic, or description of flow segments. <br /> <br />Sheet flow (Applicsble to T only) <br />c. <br /> <br />Segment ID <br /> <br />I. <br /> <br />Surfsce description (tsble 3-1) <br /> <br />............ <br /> <br />2. MAnning's roughness coeff., n (table 3-1) .. <br /> <br />3. Flow length, L (total L ~ 300 ft) .......... ft <br /> <br />4. Two-yr 24-hr rainfall, P2 .................. 1n <br /> <br />5. Land slope, 8 .............................. ft/ft <br /> <br />6. <br /> <br />T _ 0.007 (nL)0.8 <br />t p 0.5 0.4 <br />2 s <br /> <br />Compute Tt ...... <br /> <br />Shallow concentrated flow <br /> <br />Segment ID <br /> <br />f <br /> <br />7. Surfsce description (paved or unpsved) ..... <br /> <br />8. Flow length, L ............................. ft <br /> <br />9. Watercourse slope, s ....................... ft/ft <br /> <br />10. Average velocity, V (figure 3-t) ........... ftls <br /> <br />L <br />ll. Tt . 3600 V <br /> <br />Compute T ...... <br />t <br /> <br />Chann~l i lvw <br /> <br />Segment ID <br /> <br />hr <br /> <br />I <br />~. - <br />C' /.3 <br />..ftJ(:J <br />d't? <br />, t!>/.3 <br />C.1'5..f I + I <br /> <br />hr <br /> <br />~ <br />/ . <br />IJ,. <br />Z.1t'!:; <br />,t:)/3 <br />/.,r <br />tJ.3z.1+ I <br /> <br />.,;j <br /> <br />4 <br /> <br />. 12. Cross sectional flow area, a ............... ft2 <br /> 13. Wetted perimeter, Pw ....................... ft <br /> 14. Hydraulic radius, a Compute ft I. tJ3 <br /> r -- r ....... <br /> Pw <br /> 15. Channel slope, . ........................... ftlft '0 (:1' <br /> 16. Mannlng1s roughness coeff. , n .............. 'C:o.;..,r[) <br /> 1.49 2/3 1/2 <br /> V - r s Compute V ft/s <br /> ". n ....... <br /> 18. Flow lel'~,.... ~ L ............................. ft <br /> 19. T - L Compute Tt <br /> t 3600 V ...... hr <br /> <br />zz.?) <br />14.47 <br /> <br />(...n. <br />,00 <br />.~ <br /> <br />..s. t?f <br /> <br />/8', <br />(.6'1 <br /> <br /> <br /> <br />20. <br /> <br />lIatershed or s~barea Tc or Tt ,..,~~ Tt 1n steps 6, 11, and 19) ....... <br /> <br />(21o-VI.TR-55. Second Ed., June 1986) <br /> <br />-ltJ'$1 <br /> <br />-1~.3?-- I <br /> <br />~\W'~ <br />5 ~ <br />$'c,,;..J <br /> <br />I?C=\~ <br />I'" l. <br /> <br />.s-Gr;4 <br /> <br />-12.4~ I <br />hr .3,~ <br /> <br />D-3 <br />