An Improved Curve-Number Method
Publication: Journal of Irrigation and Drainage Engineering
Volume 149, Issue 2
Abstract
The standard curve-number method has shown limited accuracy in estimating observed rainfall-runoff relations, particularly for less extreme rainfall events. Consequently, the Natural Resources Conservation Service is considering revising the standard initial abstraction ratio and associated published curve numbers to improve the performance of the method. A form of the curve-number equation is presented here that improves the prediction accuracy of the curve-number method without the need to adjust the initial abstraction ratio or the existing guideline curve numbers, and the improved runoff estimation is at least as good as could be achieved by adjusting the initial abstraction ratio. The improved curve-number equation can also be used to analytically estimate curve numbers corresponding to any given initial abstraction ratio, and it is demonstrated that these estimates are supported by field measurements.
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Data Availability Statement
All data and models generated or used during the study appear in the published article.
References
Chin, D. 2022. “Essential considerations in applying the curve-number method.” J. Irrig. Drain. Eng. 148 (2): 04021071. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001649.
Hawkins, R. 1993. “Asymptotic determination of runoff curve numbers from data.” J. Irrig. Drain. Eng. 119 (2): 334–345. https://doi.org/10.1061/(ASCE)0733-9437(1993)119:2(334).
Hawkins, R., R. Jiang, D. Woodward, A. Hjelmfelt, J. V. Mullem, and Q. Quan. 2002. “Runoff curve number method: Examination of the initial abstraction ratio.” In Proc., 2nd Federal Interagency Hydrologic Modeling Conf., 629–643. Reston, VA: ASCE.
Hawkins, R., G. Moglen, T. Ward, and D. Woodward. 2020. “Updating the curve number: Task group report.” In Watershed management, 131–140. Reston, VA: ASCE.
Hawkins, R., T. Ward, D. Woodward, and J. V. Mullem. 2010. “Continuing evolution of rainfall-runoff and the curve number precedent.” In Proc., 2nd Joint Federal Interagency Conf. Las Vegas.
Lilliefors, H. 1967. “On the Kolmogorov-Smirnov test for normality with mean and variance unknown.” J. Am. Stat. Assoc. 62 (Jul): 399–402. https://doi.org/10.1080/01621459.1967.10482916.
Natural Resources Conservation Service. 2004. NRCS national engineering handbook, Part 630: Hydrology, Chapter 10: Estimation of direct runoff from storm rainfall. Washington, DC: US Department of Agriculture.
Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 149 • Issue 2 • February 2023
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Mar 15, 2022
Accepted: Nov 3, 2022
Published online: Dec 7, 2022
Published in print: Feb 1, 2023
Discussion open until: May 7, 2023
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Cited by
- David A. Chin, The Curve Number Method in the 21st Century, Journal of Irrigation and Drainage Engineering, 10.1061/JIDEDH.IRENG-10108, 149, 6, (2023).