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Woritsheet 3: Time of concentration (Tc) or travel time (Tt) <br />Project SDE~4 HyDC,i'+ Dace 7.-1-93 tTu~-sv~a3 <br />Location ACL.SS 40AD?;p~~ C++'IP Checked Date <br />Circle one: Present Developed <br />Circle one; Tc (TC~through subarea <br />NOTES: Space for ae many as ivo segments per flay type can be used for each <br />worksheet. <br />Include a map, schematic, or description of floe segments. <br />Sheet floe (Applicable to Tc only) Segment ID <br />1. Surface description (table 3-1) ............ <br />2. Hanning's roughness coeff., n (table 3-1) .. <br />]. Flow length, L (total L < 300 ft) .......... ft <br />4. Tvo-yr 24-hr rainfall, P2 .................. is <br />5. Land slope, s .............................. Ft/ft <br />6. Tt 0.0075(nOL)0.8 Compute Tt ...... hr <br />P2 a <br />Shallow concentrated floe Segment ID <br />• 7. Surface description (paved or unpaved) ..... <br />8. Flow length, L ............................. fc <br />9. Watercourse slope, s ....................... ft/ft <br />30. Average velocity, V (figure 3-1) ........... ft/s <br />11. Tc 36D0 V Compute Tt ...... hr <br />Channel Elov Segment ID <br />12. Cross sectional flow area, a ............... ft2 <br />U. Wetted perimeter, pv ....................... ft <br />l4. Hydraulic radlue, r ~ pa Compute r ....... ft <br />v <br />15. Channel slope, s ........................... Ec/ft <br />16. !lanning's roughness coeff., n .............. <br />2/] 1/2 <br />17. V ~ 1'49 ra s Compute V ....... fc/s <br />18. Flow length, L ............................. ft <br />~9. Tc 3600 V Compute Tt ...... hr <br />20. Watershed ar subarea Tc or 2t (add Tt !n steps 6, 11 <br />0.33 <br />UNPAVID <br />2200 <br />.OS <br />4.6 <br />.13 + ~ 0.13 <br />+ 0.46 <br />and 19) ....... hr <br />42-11 <br />