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<br />j) <br /> <br />Worksheet 3: Time of concentration (Tc) or travel time (Tt) <br /> <br />BY~c..dr Oate ,,~ <br /> <br />Project <br /> <br />/ --"/n ~ -rRli'G <br />;:i'i>RIHl'; a e. <br /> <br />Checked <br /> <br />Pate <br /> <br />Locatlon <br /> <br /> <br />Circle one: <br />Circle one' <br /> <br />/-2- <br /> <br />NOTES: Space for.. many al two legments per flow type can be uaed for eacb <br />worksheet. <br /> <br />Include a map, Icbematic, or description of flow aegments. <br /> <br />Sbeet flow (Applicable to Tc only) <br /> <br /> <br />Segment ID <br /> <br />1. <br /> <br />Surface descdption (table 3-1) <br /> <br />............ <br /> <br />2. Mannlng's rougbness coeff., n (table 3-1) .. tJ,l <br /> <br />3. Flow lengtb, L (toUI L.i 300 ft) .......... ft <br /> <br /> <br />4. Two-yr 24-br rainfall, '2 .................. in <br /> <br />.~. <br /> <br />5. Land slope, I .............................. <br />T . 0.001 (nL)0.8 <br />t p 0.5 0.4 Compute Tt ...... <br />2 · <br /> <br />ftlft <br /> <br />6. <br /> <br />br <br /> <br />. ~.5& I <br /> <br /> Sballow concentrated flow Segment 10 <br /> 7. Surface deacription (paved or unpaved) ..... <br />, . <br /> '( 8. Flow length, L ............................. ft <br /> 9. Watercourse elope, I ....................... ftlft <br /> 10. Average velocity, Y (figure 3-1) ........... ft/a <br /> 11. L Compute Tt br .12.~~1 <br /> Tt . 3600 Y ...... <br /> <br />Channel flow Segment ID .3 <br />12. Croas aecUona! flov area. . ............... ft2 &2.t> <br />13. Wetted perimeter, 'v....................... ft 14.47 <br />14. Hydraulic radius, a Compute r ....... ft /.2.7 /.S'L <br />r .- <br />Pw <br />15. Channel slope, I ........................... ftlft ,()O2 .~~tP <br />16. Manning'. roughness coeff.. n .............. 'I7n . ~.s-O <br />17. V. 1.49 r213 .1/2 Compute V....... ftls .$.1.3 $,(/';- <br />D <br />18. Flow lengtb, L ............................. ft .J?$t7 " 7t7P <br />19. L Compute Tt 3.2.2. + 6.77 <br />Tt . 3600 Y ...... br <br /> <br />20. Watersbed or subarea Te or Tt (add Tt in steps 6, II, and 19) ..,.... <br /> <br />c <br /> <br />(210-VI.TR-55, Second Ed., June 1986) <br /> <br />=-\ Tz.~ IF <br />~~ <br /> <br />r~'3 <br /> <br />~kAF <br />, V. <br />n!J ~ <br /> <br />fCG.of <br /> <br />b:~.~1 <br /> <br />0.3 <br />