Rational-Method Equation and HEC TD-15
Publication: Journal of Irrigation and Drainage Engineering
Volume 122, Issue 1
Abstract
The rational-method equation for estimating peak flow rates for storm-water runoff is derived from the balanced-design storm unit hydrograph approach presented in the U.S. Army Corps of Engineers HEC Training Document 15. The new form of the rational-method equation is Q p = (αI−φ) A, instead of the well known Q p = ( I −φ) A ; or Q p =αCIA, instead of the well known Q p =CIA, depending on the respective loss function used in the unit hydrograph effective rainfall model. The preceding fixed constant α is found to depend on the type of unit hydrograph used (i.e., S -Graph) and the log-log slope of the rainfall depth-duration curve, and is easily determined by equating to a known unit hydrograph design storm model peak flow rate result. This new development provides a significant foundation for the use of the well-known rational-method equation in small catchments where rainfall depth-area effects are negligible.
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References
1.
Hromadka II, T. V., McCuen, R. H., Durbin, T. J., and DeVries, J. J. (1994). Computer methods in environmental and water resources engineering . Lighthouse Publications, Mission Viejo, Calif.
2.
Hromadka II, T. V., and Whitley, R. J. (1989). Stochastic integral equations in rainfall-runoff modeling . Springer-Verlag, New York, N.Y.
3.
Hromadka II, T. V., McCuen, R. H., and Yen, C. C. (1987). Computational hydrology in flood control design and planning . Lighthouse Publications, Mission Viejo, Calif.
4.
Hromadka II, T. V. (1987). Orange county hydrology manual . County of Orange, Santa Ana, Calif.
5.
Hromadka II, T. V. (1986). County of San Bernardino hydrology manual . San Bernardino, Calif.
6.
Hromadka II, T. V. (1992). County of Kern hydrology manual . Bakersfield, Calif.
7.
“Hydrologic Analysis of Ungauged Watersheds Using HEC-1.” (1982). Hydrologic engineering center (HEC) training document TD-15, U.S. Army Corps of Engrs., Davis, Calif.
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Published In
Journal of Irrigation and Drainage Engineering
Volume 122 • Issue 1 • January 1996
Pages: 15 - 18
Copyright
Copyright © 1996 American Society of Civil Engineers.
History
Published online: Jan 1, 1996
Published in print: Jan 1996
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