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— Time of Concentration

Watershed time of concentration by the Kirpich, FAA, or NRCS (SCS) lag method. Kirpich and FAA use US customary length (ft); results are reported in minutes and hours.

Solution

History

Sources:
[1] Z. P. Kirpich, "Time of concentration of small agricultural watersheds," Civil Eng., vol. 10, no. 6, p. 362, 1940.
[2] Surface Drainage Design, FAA Advisory Circular 150/5320-5. Washington, DC, USA: Federal Aviation Administration.
[3] Urban Hydrology for Small Watersheds, Technical Release 55 (TR-55). Washington, DC, USA: USDA Natural Resources Conservation Service, 1986.
[4] V. T. Chow, D. R. Maidment, and L. W. Mays, Applied Hydrology, 2nd ed. New York, NY, USA: McGraw-Hill Education, 2013.

Reference content only — not a substitute for professional engineering judgment. Verify all values, tolerances, and specifications against current official standards before use in production or safety-critical work. Provided without warranty of accuracy or fitness for any purpose.