Effects of Rainfall Intensity on Runoff Curve Numbers

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Author
Hawkins, R. H.
Affiliation
Watershed Science Unit, Department of Forestry and Outdoor Recreation, Utah State University, Logan, Utah, 84322
Issue Date
1978-04-15
Keywords
Hydrology -- Arizona.
Water resources development -- Arizona.
Hydrology -- Southwestern states.
Water resources development -- Southwestern states.
Rainfall-runoff relationships
Storm runoff
Runoff coefficient
Curves
Rainfall intensity
Infiltration

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Copyright ©, where appropriate, is held by the author.
Collection Information
This article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact anashydrology@gmail.com.
Publisher
Arizona-Nevada Academy of Science
Journal
Hydrology and Water Resources in Arizona and the Southwest
Abstract
The runoff curve number rainfall- runoff relationships may be defined in two ways: (1) by formula, which uses total storm rainfall and a curve number, but not intensity or duration descriptors; and (2) rainfall loss accounting using a 4, rate and a specific intensity duration distribution of the function i(t) = 1.5P(5(1 +24t /T)-(1/2)-1) /T, where i(t) is the intensity at time t for a storm of duration T. Thus, the curve number method is found to be a special case of φ index loss accounting. The two methods are reconciled through the identity 1.2S = φT, leading to the relationship CN - 1200/(12 +φT). The effects of rainfall intensity on curve number are felt through deviations from the necessary causative intensity - duration curve. Some sample alternate distributions are explored and the effects on curve number shown. Limitations are discussed.
ISSN
0272-6106
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