Designing Spillway Crests for High-Head Operation

by John J. Cassidy, (M.ASCE), Prof. of Civ. Engrg.; Univ. of Missouri, Columbia, MO,

Serial Information: Journal of the Hydraulics Division, 1970, Vol. 96, Issue 3, Pg. 745-753

Document Type: Journal Paper

Discussion: van der Gugten Cornelis A. (See full record)
Discussion: Smith C. D. (See full record)
Discussion: Rao Singamsetti Surya (See full record)
Discussion: Abecasis Fernando M. (See full record)
Discussion: Seetharaman S. (See full record)
Closure: (See full record)


A standard-shaped spillway, when operating at greater than design head, experiences a subatmospheric crest pressure. Quantitative data obtained from laboratory measurements of minimum pressure and discharge occurring during flow over spillways are presented in dimensionless form. Minimum crest pressures as well as discharge coefficients are shown to be functions of the spillway design-head-to-height and head-to-design-head ratios. A dimensionless parameter involving discharge and minimum pressure, but not head, is formulated and evaluated. The results are used in a numerical design example to proportion a standard-shaped spillway to pass a particular discharge with a predetermined pressure occurring on the crest. The resulting design is compared with an actual design for the same spillway.

Subject Headings: Spillways | Hydraulic design | Flow measurement | Head (fluid mechanics) | Water discharge measurement | Pressure measurement | Pressurized flow | Laboratory tests

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