Subcritical Kinematic Flow in a Stable Stream

by William J. Gburek, (A.M.ASCE), Res. Hydr. Engr.; Northeast Watershed Res. Ctr., USDA-ARS, University Park, PA,
Donald E. Overton, (A.M.ASCE), Asst Prof. of Civ. Engrg.; Univ. of Tennessee, Knoxville, TN,

Serial Information: Journal of the Hydraulics Division, 1973, Vol. 99, Issue 9, Pg. 1433-1447

Document Type: Journal Paper


An evaluation of the shallow water equations in the lower 6.9 miles (11.1 km) of a stable, gently sloped tributary to the Susquehanna River showed that subcritical kinematic flow exists. Although loops were suspected, single-value rating functions within small statistical error were established at four points along the stream. Also, single Manning n-values within very small statistical error were established at each point. It was shown explicitly, however, that use of a single-valued rating function does not permit simultaneous use of a single resistance coefficient or vice versa. Use of a single resistance coefficient independent of stage will induce a loop rating function. This apparent inconsistency was resolved by reformulating the characteristic equations in terms of the exponent of the single-valued rating function used. Therefore, for the special case of subcritical kinematic flows, streamflow synthesis may be accomplished without resort to extrapolation of uniform flow formulas to unsteady nonuniform flow.

Subject Headings: Nonuniform flow | Ratings | Errors (statistics) | Unsteady flow | Kinematics | Subcritical flow | Rivers and streams | River flow

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