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~~~d~x C <br />Worksheet 3: Time of concentration (Tc) or travel time (Tt) <br />Project Wr~~~ /'~~~e Sy ,ZJ~ Date Io-LS-O~ <br />Location G(p S~ope ~r'o nt I.~~s•/e ,~Wet~ Checked Date <br />Ctrc le one: Prese Developed <br />Circle one: Tt through subarea <br />NOTES: Space for as many as two segments per flow type can be used for each <br />worksheet. <br />Include a map, schematic, oc description of flow segments. <br />Sheet flow (Applicable to Tc only) Segment ID <br />1. Surface description (table 3-1) ............ <br />2. Manning's roughness coef£., n (table 3-1) .. <br />3. Flow length, L {total L < 300 ft) .......... ft <br />4, Two-yr 24-hr rainfall, P2 .................. in <br />5. Land slope, s .............................. ft/f[ <br />6. Tt 0.00075{nL0)~'8 Compute TC ...... hr <br />P2 s <br />Shallow concentrated flow Segment ID <br />7. Surface description (paved or unpaved) ..... <br />8. Flow length, L ............................. ft <br />9. Watercourse slope, s ....................... f[/ft <br />!0. Average velocity, V (figure 3-1) ........... ft/s <br />11. Tt 3600 V Compute Tt ...... hr <br />Channel flow Segment ID <br />12. Cross sec[Sonal fiow area, a ............... ft2 <br />13. We[[ed pe rime[e r, pw ....................... ft <br />I4. Hydraulic radius, r Pa Compute r ....... ft <br />w <br />15. Channel slope, s ........................... ft/ft <br />16. Manning's roughness coe£f ., n .............. <br />1.49 c2/3 sl/2 <br />17. V = n Compute V ....... ft/s <br />18. Flow length, L ............................. ft <br />19. Tt 3600 V Compute Tt ,,,,,, hr <br />20. Watershed or subarea Tc or Tt (add TC in steps 6, 1 <br />su66as,n l Sabdatin Z <br />~-b %-B <br />p,+3 a.+3 <br />zgv z8o <br />I•I /,l <br />.O,IS D,zS <br />O.zS3 • °•206 <br />B-c S-c <br />unVa/e~ NO pa/e.~ <br />S SD 12. DO <br />D, ~s a /7 <br />S, P ~. 7 <br />0.02 (~ f O,OS <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />+ 0.279 s~bbn:,~ ) <br />and 19) ....... hr D.2$"6 SvblX+ti+ Z <br />